/usr/share/pyshared/sqlalchemy/engine/base.py is in python-sqlalchemy 0.7.4-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 1344 1345 1346 1347 1348 1349 1350 1351 1352 1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364 1365 1366 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448 1449 1450 1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481 1482 1483 1484 1485 1486 1487 1488 1489 1490 1491 1492 1493 1494 1495 1496 1497 1498 1499 1500 1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 1511 1512 1513 1514 1515 1516 1517 1518 1519 1520 1521 1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534 1535 1536 1537 1538 1539 1540 1541 1542 1543 1544 1545 1546 1547 1548 1549 1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562 1563 1564 1565 1566 1567 1568 1569 1570 1571 1572 1573 1574 1575 1576 1577 1578 1579 1580 1581 1582 1583 1584 1585 1586 1587 1588 1589 1590 1591 1592 1593 1594 1595 1596 1597 1598 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608 1609 1610 1611 1612 1613 1614 1615 1616 1617 1618 1619 1620 1621 1622 1623 1624 1625 1626 1627 1628 1629 1630 1631 1632 1633 1634 1635 1636 1637 1638 1639 1640 1641 1642 1643 1644 1645 1646 1647 1648 1649 1650 1651 1652 1653 1654 1655 1656 1657 1658 1659 1660 1661 1662 1663 1664 1665 1666 1667 1668 1669 1670 1671 1672 1673 1674 1675 1676 1677 1678 1679 1680 1681 1682 1683 1684 1685 1686 1687 1688 1689 1690 1691 1692 1693 1694 1695 1696 1697 1698 1699 1700 1701 1702 1703 1704 1705 1706 1707 1708 1709 1710 1711 1712 1713 1714 1715 1716 1717 1718 1719 1720 1721 1722 1723 1724 1725 1726 1727 1728 1729 1730 1731 1732 1733 1734 1735 1736 1737 1738 1739 1740 1741 1742 1743 1744 1745 1746 1747 1748 1749 1750 1751 1752 1753 1754 1755 1756 1757 1758 1759 1760 1761 1762 1763 1764 1765 1766 1767 1768 1769 1770 1771 1772 1773 1774 1775 1776 1777 1778 1779 1780 1781 1782 1783 1784 1785 1786 1787 1788 1789 1790 1791 1792 1793 1794 1795 1796 1797 1798 1799 1800 1801 1802 1803 1804 1805 1806 1807 1808 1809 1810 1811 1812 1813 1814 1815 1816 1817 1818 1819 1820 1821 1822 1823 1824 1825 1826 1827 1828 1829 1830 1831 1832 1833 1834 1835 1836 1837 1838 1839 1840 1841 1842 1843 1844 1845 1846 1847 1848 1849 1850 1851 1852 1853 1854 1855 1856 1857 1858 1859 1860 1861 1862 1863 1864 1865 1866 1867 1868 1869 1870 1871 1872 1873 1874 1875 1876 1877 1878 1879 1880 1881 1882 1883 1884 1885 1886 1887 1888 1889 1890 1891 1892 1893 1894 1895 1896 1897 1898 1899 1900 1901 1902 1903 1904 1905 1906 1907 1908 1909 1910 1911 1912 1913 1914 1915 1916 1917 1918 1919 1920 1921 1922 1923 1924 1925 1926 1927 1928 1929 1930 1931 1932 1933 1934 1935 1936 1937 1938 1939 1940 1941 1942 1943 1944 1945 1946 1947 1948 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034 2035 2036 2037 2038 2039 2040 2041 2042 2043 2044 2045 2046 2047 2048 2049 2050 2051 2052 2053 2054 2055 2056 2057 2058 2059 2060 2061 2062 2063 2064 2065 2066 2067 2068 2069 2070 2071 2072 2073 2074 2075 2076 2077 2078 2079 2080 2081 2082 2083 2084 2085 2086 2087 2088 2089 2090 2091 2092 2093 2094 2095 2096 2097 2098 2099 2100 2101 2102 2103 2104 2105 2106 2107 2108 2109 2110 2111 2112 2113 2114 2115 2116 2117 2118 2119 2120 2121 2122 2123 2124 2125 2126 2127 2128 2129 2130 2131 2132 2133 2134 2135 2136 2137 2138 2139 2140 2141 2142 2143 2144 2145 2146 2147 2148 2149 2150 2151 2152 2153 2154 2155 2156 2157 2158 2159 2160 2161 2162 2163 2164 2165 2166 2167 2168 2169 2170 2171 2172 2173 2174 2175 2176 2177 2178 2179 2180 2181 2182 2183 2184 2185 2186 2187 2188 2189 2190 2191 2192 2193 2194 2195 2196 2197 2198 2199 2200 2201 2202 2203 2204 2205 2206 2207 2208 2209 2210 2211 2212 2213 2214 2215 2216 2217 2218 2219 2220 2221 2222 2223 2224 2225 2226 2227 2228 2229 2230 2231 2232 2233 2234 2235 2236 2237 2238 2239 2240 2241 2242 2243 2244 2245 2246 2247 2248 2249 2250 2251 2252 2253 2254 2255 2256 2257 2258 2259 2260 2261 2262 2263 2264 2265 2266 2267 2268 2269 2270 2271 2272 2273 2274 2275 2276 2277 2278 2279 2280 2281 2282 2283 2284 2285 2286 2287 2288 2289 2290 2291 2292 2293 2294 2295 2296 2297 2298 2299 2300 2301 2302 2303 2304 2305 2306 2307 2308 2309 2310 2311 2312 2313 2314 2315 2316 2317 2318 2319 2320 2321 2322 2323 2324 2325 2326 2327 2328 2329 2330 2331 2332 2333 2334 2335 2336 2337 2338 2339 2340 2341 2342 2343 2344 2345 2346 2347 2348 2349 2350 2351 2352 2353 2354 2355 2356 2357 2358 2359 2360 2361 2362 2363 2364 2365 2366 2367 2368 2369 2370 2371 2372 2373 2374 2375 2376 2377 2378 2379 2380 2381 2382 2383 2384 2385 2386 2387 2388 2389 2390 2391 2392 2393 2394 2395 2396 2397 2398 2399 2400 2401 2402 2403 2404 2405 2406 2407 2408 2409 2410 2411 2412 2413 2414 2415 2416 2417 2418 2419 2420 2421 2422 2423 2424 2425 2426 2427 2428 2429 2430 2431 2432 2433 2434 2435 2436 2437 2438 2439 2440 2441 2442 2443 2444 2445 2446 2447 2448 2449 2450 2451 2452 2453 2454 2455 2456 2457 2458 2459 2460 2461 2462 2463 2464 2465 2466 2467 2468 2469 2470 2471 2472 2473 2474 2475 2476 2477 2478 2479 2480 2481 2482 2483 2484 2485 2486 2487 2488 2489 2490 2491 2492 2493 2494 2495 2496 2497 2498 2499 2500 2501 2502 2503 2504 2505 2506 2507 2508 2509 2510 2511 2512 2513 2514 2515 2516 2517 2518 2519 2520 2521 2522 2523 2524 2525 2526 2527 2528 2529 2530 2531 2532 2533 2534 2535 2536 2537 2538 2539 2540 2541 2542 2543 2544 2545 2546 2547 2548 2549 2550 2551 2552 2553 2554 2555 2556 2557 2558 2559 2560 2561 2562 2563 2564 2565 2566 2567 2568 2569 2570 2571 2572 2573 2574 2575 2576 2577 2578 2579 2580 2581 2582 2583 2584 2585 2586 2587 2588 2589 2590 2591 2592 2593 2594 2595 2596 2597 2598 2599 2600 2601 2602 2603 2604 2605 2606 2607 2608 2609 2610 2611 2612 2613 2614 2615 2616 2617 2618 2619 2620 2621 2622 2623 2624 2625 2626 2627 2628 2629 2630 2631 2632 2633 2634 2635 2636 2637 2638 2639 2640 2641 2642 2643 2644 2645 2646 2647 2648 2649 2650 2651 2652 2653 2654 2655 2656 2657 2658 2659 2660 2661 2662 2663 2664 2665 2666 2667 2668 2669 2670 2671 2672 2673 2674 2675 2676 2677 2678 2679 2680 2681 2682 2683 2684 2685 2686 2687 2688 2689 2690 2691 2692 2693 2694 2695 2696 2697 2698 2699 2700 2701 2702 2703 2704 2705 2706 2707 2708 2709 2710 2711 2712 2713 2714 2715 2716 2717 2718 2719 2720 2721 2722 2723 2724 2725 2726 2727 2728 2729 2730 2731 2732 2733 2734 2735 2736 2737 2738 2739 2740 2741 2742 2743 2744 2745 2746 2747 2748 2749 2750 2751 2752 2753 2754 2755 2756 2757 2758 2759 2760 2761 2762 2763 2764 2765 2766 2767 2768 2769 2770 2771 2772 2773 2774 2775 2776 2777 2778 2779 2780 2781 2782 2783 2784 2785 2786 2787 2788 2789 2790 2791 2792 2793 2794 2795 2796 2797 2798 2799 2800 2801 2802 2803 2804 2805 2806 2807 2808 2809 2810 2811 2812 2813 2814 2815 2816 2817 2818 2819 2820 2821 2822 2823 2824 2825 2826 2827 2828 2829 2830 2831 2832 2833 2834 2835 2836 2837 2838 2839 2840 2841 2842 2843 2844 2845 2846 2847 2848 2849 2850 2851 2852 2853 2854 2855 2856 2857 2858 2859 2860 2861 2862 2863 2864 2865 2866 2867 2868 2869 2870 2871 2872 2873 2874 2875 2876 2877 2878 2879 2880 2881 2882 2883 2884 2885 2886 2887 2888 2889 2890 2891 2892 2893 2894 2895 2896 2897 2898 2899 2900 2901 2902 2903 2904 2905 2906 2907 2908 2909 2910 2911 2912 2913 2914 2915 2916 2917 2918 2919 2920 2921 2922 2923 2924 2925 2926 2927 2928 2929 2930 2931 2932 2933 2934 2935 2936 2937 2938 2939 2940 2941 2942 2943 2944 2945 2946 2947 2948 2949 2950 2951 2952 2953 2954 2955 2956 2957 2958 2959 2960 2961 2962 2963 2964 2965 2966 2967 2968 2969 2970 2971 2972 2973 2974 2975 2976 2977 2978 2979 2980 2981 2982 2983 2984 2985 2986 2987 2988 2989 2990 2991 2992 2993 2994 2995 2996 2997 2998 2999 3000 3001 3002 3003 3004 3005 3006 3007 3008 3009 3010 3011 3012 3013 3014 3015 3016 3017 3018 3019 3020 3021 3022 3023 3024 3025 3026 3027 3028 3029 3030 3031 3032 3033 3034 3035 3036 3037 3038 3039 3040 3041 3042 3043 3044 3045 3046 3047 3048 3049 3050 3051 3052 3053 3054 3055 3056 3057 3058 3059 3060 3061 3062 3063 3064 3065 3066 3067 3068 3069 3070 3071 3072 3073 3074 3075 3076 3077 3078 3079 3080 3081 3082 3083 3084 3085 3086 3087 3088 3089 3090 3091 3092 3093 3094 3095 3096 3097 3098 3099 3100 3101 3102 3103 3104 3105 3106 3107 3108 3109 3110 3111 3112 3113 3114 3115 3116 3117 3118 3119 3120 3121 3122 3123 3124 3125 3126 3127 3128 3129 3130 3131 3132 3133 3134 3135 3136 3137 3138 3139 3140 3141 3142 3143 3144 3145 3146 3147 3148 3149 3150 3151 3152 3153 3154 3155 3156 3157 3158 3159 3160 3161 3162 3163 3164 3165 3166 3167 3168 3169 3170 3171 3172 3173 3174 3175 3176 3177 3178 3179 3180 3181 3182 3183 3184 3185 3186 3187 3188 3189 3190 3191 3192 3193 3194 3195 3196 3197 3198 3199 3200 3201 3202 3203 3204 3205 3206 3207 3208 3209 3210 3211 3212 3213 3214 3215 3216 3217 3218 3219 3220 3221 3222 3223 3224 3225 3226 3227 3228 3229 3230 3231 3232 3233 3234 3235 3236 3237 3238 3239 3240 3241 3242 3243 3244 3245 3246 3247 3248 3249 3250 3251 3252 3253 3254 3255 3256 3257 3258 3259 3260 | # engine/base.py
# Copyright (C) 2005-2011 the SQLAlchemy authors and contributors <see AUTHORS file>
#
# This module is part of SQLAlchemy and is released under
# the MIT License: http://www.opensource.org/licenses/mit-license.php
"""Basic components for SQL execution and interfacing with DB-API.
Defines the basic components used to interface DB-API modules with
higher-level statement-construction, connection-management, execution
and result contexts.
"""
__all__ = [
'BufferedColumnResultProxy', 'BufferedColumnRow',
'BufferedRowResultProxy','Compiled', 'Connectable', 'Connection',
'Dialect', 'Engine','ExecutionContext', 'NestedTransaction',
'ResultProxy', 'RootTransaction','RowProxy', 'SchemaIterator',
'StringIO', 'Transaction', 'TwoPhaseTransaction',
'connection_memoize']
import inspect, StringIO, sys, operator
from itertools import izip
from sqlalchemy import exc, schema, util, types, log, interfaces, \
event, events
from sqlalchemy.sql import expression, util as sql_util
from sqlalchemy import processors
import collections
class Dialect(object):
"""Define the behavior of a specific database and DB-API combination.
Any aspect of metadata definition, SQL query generation,
execution, result-set handling, or anything else which varies
between databases is defined under the general category of the
Dialect. The Dialect acts as a factory for other
database-specific object implementations including
ExecutionContext, Compiled, DefaultGenerator, and TypeEngine.
All Dialects implement the following attributes:
name
identifying name for the dialect from a DBAPI-neutral point of view
(i.e. 'sqlite')
driver
identifying name for the dialect's DBAPI
positional
True if the paramstyle for this Dialect is positional.
paramstyle
the paramstyle to be used (some DB-APIs support multiple
paramstyles).
convert_unicode
True if Unicode conversion should be applied to all ``str``
types.
encoding
type of encoding to use for unicode, usually defaults to
'utf-8'.
statement_compiler
a :class:`~Compiled` class used to compile SQL statements
ddl_compiler
a :class:`~Compiled` class used to compile DDL statements
server_version_info
a tuple containing a version number for the DB backend in use.
This value is only available for supporting dialects, and is
typically populated during the initial connection to the database.
default_schema_name
the name of the default schema. This value is only available for
supporting dialects, and is typically populated during the
initial connection to the database.
execution_ctx_cls
a :class:`.ExecutionContext` class used to handle statement execution
execute_sequence_format
either the 'tuple' or 'list' type, depending on what cursor.execute()
accepts for the second argument (they vary).
preparer
a :class:`~sqlalchemy.sql.compiler.IdentifierPreparer` class used to
quote identifiers.
supports_alter
``True`` if the database supports ``ALTER TABLE``.
max_identifier_length
The maximum length of identifier names.
supports_unicode_statements
Indicate whether the DB-API can receive SQL statements as Python
unicode strings
supports_unicode_binds
Indicate whether the DB-API can receive string bind parameters
as Python unicode strings
supports_sane_rowcount
Indicate whether the dialect properly implements rowcount for
``UPDATE`` and ``DELETE`` statements.
supports_sane_multi_rowcount
Indicate whether the dialect properly implements rowcount for
``UPDATE`` and ``DELETE`` statements when executed via
executemany.
preexecute_autoincrement_sequences
True if 'implicit' primary key functions must be executed separately
in order to get their value. This is currently oriented towards
Postgresql.
implicit_returning
use RETURNING or equivalent during INSERT execution in order to load
newly generated primary keys and other column defaults in one execution,
which are then available via inserted_primary_key.
If an insert statement has returning() specified explicitly,
the "implicit" functionality is not used and inserted_primary_key
will not be available.
dbapi_type_map
A mapping of DB-API type objects present in this Dialect's
DB-API implementation mapped to TypeEngine implementations used
by the dialect.
This is used to apply types to result sets based on the DB-API
types present in cursor.description; it only takes effect for
result sets against textual statements where no explicit
typemap was present.
colspecs
A dictionary of TypeEngine classes from sqlalchemy.types mapped
to subclasses that are specific to the dialect class. This
dictionary is class-level only and is not accessed from the
dialect instance itself.
supports_default_values
Indicates if the construct ``INSERT INTO tablename DEFAULT
VALUES`` is supported
supports_sequences
Indicates if the dialect supports CREATE SEQUENCE or similar.
sequences_optional
If True, indicates if the "optional" flag on the Sequence() construct
should signal to not generate a CREATE SEQUENCE. Applies only to
dialects that support sequences. Currently used only to allow Postgresql
SERIAL to be used on a column that specifies Sequence() for usage on
other backends.
supports_native_enum
Indicates if the dialect supports a native ENUM construct.
This will prevent types.Enum from generating a CHECK
constraint when that type is used.
supports_native_boolean
Indicates if the dialect supports a native boolean construct.
This will prevent types.Boolean from generating a CHECK
constraint when that type is used.
"""
def create_connect_args(self, url):
"""Build DB-API compatible connection arguments.
Given a :class:`~sqlalchemy.engine.url.URL` object, returns a tuple
consisting of a `*args`/`**kwargs` suitable to send directly
to the dbapi's connect function.
"""
raise NotImplementedError()
@classmethod
def type_descriptor(cls, typeobj):
"""Transform a generic type to a dialect-specific type.
Dialect classes will usually use the
:func:`~sqlalchemy.types.adapt_type` function in the types module to
make this job easy.
The returned result is cached *per dialect class* so can
contain no dialect-instance state.
"""
raise NotImplementedError()
def initialize(self, connection):
"""Called during strategized creation of the dialect with a
connection.
Allows dialects to configure options based on server version info or
other properties.
The connection passed here is a SQLAlchemy Connection object,
with full capabilities.
The initalize() method of the base dialect should be called via
super().
"""
pass
def reflecttable(self, connection, table, include_columns=None):
"""Load table description from the database.
Given a :class:`.Connection` and a
:class:`~sqlalchemy.schema.Table` object, reflect its columns and
properties from the database. If include_columns (a list or
set) is specified, limit the autoload to the given column
names.
The default implementation uses the
:class:`~sqlalchemy.engine.reflection.Inspector` interface to
provide the output, building upon the granular table/column/
constraint etc. methods of :class:`.Dialect`.
"""
raise NotImplementedError()
def get_columns(self, connection, table_name, schema=None, **kw):
"""Return information about columns in `table_name`.
Given a :class:`.Connection`, a string
`table_name`, and an optional string `schema`, return column
information as a list of dictionaries with these keys:
name
the column's name
type
[sqlalchemy.types#TypeEngine]
nullable
boolean
default
the column's default value
autoincrement
boolean
sequence
a dictionary of the form
{'name' : str, 'start' :int, 'increment': int}
Additional column attributes may be present.
"""
raise NotImplementedError()
def get_primary_keys(self, connection, table_name, schema=None, **kw):
"""Return information about primary keys in `table_name`.
Given a :class:`.Connection`, a string
`table_name`, and an optional string `schema`, return primary
key information as a list of column names.
"""
raise NotImplementedError()
def get_pk_constraint(self, table_name, schema=None, **kw):
"""Return information about the primary key constraint on
table_name`.
Given a string `table_name`, and an optional string `schema`, return
primary key information as a dictionary with these keys:
constrained_columns
a list of column names that make up the primary key
name
optional name of the primary key constraint.
"""
raise NotImplementedError()
def get_foreign_keys(self, connection, table_name, schema=None, **kw):
"""Return information about foreign_keys in `table_name`.
Given a :class:`.Connection`, a string
`table_name`, and an optional string `schema`, return foreign
key information as a list of dicts with these keys:
name
the constraint's name
constrained_columns
a list of column names that make up the foreign key
referred_schema
the name of the referred schema
referred_table
the name of the referred table
referred_columns
a list of column names in the referred table that correspond to
constrained_columns
"""
raise NotImplementedError()
def get_table_names(self, connection, schema=None, **kw):
"""Return a list of table names for `schema`."""
raise NotImplementedError
def get_view_names(self, connection, schema=None, **kw):
"""Return a list of all view names available in the database.
schema:
Optional, retrieve names from a non-default schema.
"""
raise NotImplementedError()
def get_view_definition(self, connection, view_name, schema=None, **kw):
"""Return view definition.
Given a :class:`.Connection`, a string
`view_name`, and an optional string `schema`, return the view
definition.
"""
raise NotImplementedError()
def get_indexes(self, connection, table_name, schema=None, **kw):
"""Return information about indexes in `table_name`.
Given a :class:`.Connection`, a string
`table_name` and an optional string `schema`, return index
information as a list of dictionaries with these keys:
name
the index's name
column_names
list of column names in order
unique
boolean
"""
raise NotImplementedError()
def normalize_name(self, name):
"""convert the given name to lowercase if it is detected as
case insensitive.
this method is only used if the dialect defines
requires_name_normalize=True.
"""
raise NotImplementedError()
def denormalize_name(self, name):
"""convert the given name to a case insensitive identifier
for the backend if it is an all-lowercase name.
this method is only used if the dialect defines
requires_name_normalize=True.
"""
raise NotImplementedError()
def has_table(self, connection, table_name, schema=None):
"""Check the existence of a particular table in the database.
Given a :class:`.Connection` object and a string
`table_name`, return True if the given table (possibly within
the specified `schema`) exists in the database, False
otherwise.
"""
raise NotImplementedError()
def has_sequence(self, connection, sequence_name, schema=None):
"""Check the existence of a particular sequence in the database.
Given a :class:`.Connection` object and a string
`sequence_name`, return True if the given sequence exists in
the database, False otherwise.
"""
raise NotImplementedError()
def _get_server_version_info(self, connection):
"""Retrieve the server version info from the given connection.
This is used by the default implementation to populate the
"server_version_info" attribute and is called exactly
once upon first connect.
"""
raise NotImplementedError()
def _get_default_schema_name(self, connection):
"""Return the string name of the currently selected schema from
the given connection.
This is used by the default implementation to populate the
"default_schema_name" attribute and is called exactly
once upon first connect.
"""
raise NotImplementedError()
def do_begin(self, connection):
"""Provide an implementation of *connection.begin()*, given a
DB-API connection."""
raise NotImplementedError()
def do_rollback(self, connection):
"""Provide an implementation of *connection.rollback()*, given
a DB-API connection."""
raise NotImplementedError()
def create_xid(self):
"""Create a two-phase transaction ID.
This id will be passed to do_begin_twophase(),
do_rollback_twophase(), do_commit_twophase(). Its format is
unspecified.
"""
raise NotImplementedError()
def do_commit(self, connection):
"""Provide an implementation of *connection.commit()*, given a
DB-API connection."""
raise NotImplementedError()
def do_savepoint(self, connection, name):
"""Create a savepoint with the given name on a SQLAlchemy
connection."""
raise NotImplementedError()
def do_rollback_to_savepoint(self, connection, name):
"""Rollback a SQL Alchemy connection to the named savepoint."""
raise NotImplementedError()
def do_release_savepoint(self, connection, name):
"""Release the named savepoint on a SQL Alchemy connection."""
raise NotImplementedError()
def do_begin_twophase(self, connection, xid):
"""Begin a two phase transaction on the given connection."""
raise NotImplementedError()
def do_prepare_twophase(self, connection, xid):
"""Prepare a two phase transaction on the given connection."""
raise NotImplementedError()
def do_rollback_twophase(self, connection, xid, is_prepared=True,
recover=False):
"""Rollback a two phase transaction on the given connection."""
raise NotImplementedError()
def do_commit_twophase(self, connection, xid, is_prepared=True,
recover=False):
"""Commit a two phase transaction on the given connection."""
raise NotImplementedError()
def do_recover_twophase(self, connection):
"""Recover list of uncommited prepared two phase transaction
identifiers on the given connection."""
raise NotImplementedError()
def do_executemany(self, cursor, statement, parameters, context=None):
"""Provide an implementation of *cursor.executemany(statement,
parameters)*."""
raise NotImplementedError()
def do_execute(self, cursor, statement, parameters, context=None):
"""Provide an implementation of *cursor.execute(statement,
parameters)*."""
raise NotImplementedError()
def is_disconnect(self, e, connection, cursor):
"""Return True if the given DB-API error indicates an invalid
connection"""
raise NotImplementedError()
def connect(self):
"""return a callable which sets up a newly created DBAPI connection.
The callable accepts a single argument "conn" which is the
DBAPI connection itself. It has no return value.
This is used to set dialect-wide per-connection options such as
isolation modes, unicode modes, etc.
If a callable is returned, it will be assembled into a pool listener
that receives the direct DBAPI connection, with all wrappers removed.
If None is returned, no listener will be generated.
"""
return None
def reset_isolation_level(self, dbapi_conn):
"""Given a DBAPI connection, revert its isolation to the default."""
raise NotImplementedError()
def set_isolation_level(self, dbapi_conn, level):
"""Given a DBAPI connection, set its isolation level."""
raise NotImplementedError()
def get_isolation_level(self, dbapi_conn):
"""Given a DBAPI connection, return its isolation level."""
raise NotImplementedError()
class ExecutionContext(object):
"""A messenger object for a Dialect that corresponds to a single
execution.
ExecutionContext should have these data members:
connection
Connection object which can be freely used by default value
generators to execute SQL. This Connection should reference the
same underlying connection/transactional resources of
root_connection.
root_connection
Connection object which is the source of this ExecutionContext. This
Connection may have close_with_result=True set, in which case it can
only be used once.
dialect
dialect which created this ExecutionContext.
cursor
DB-API cursor procured from the connection,
compiled
if passed to constructor, sqlalchemy.engine.base.Compiled object
being executed,
statement
string version of the statement to be executed. Is either
passed to the constructor, or must be created from the
sql.Compiled object by the time pre_exec() has completed.
parameters
bind parameters passed to the execute() method. For compiled
statements, this is a dictionary or list of dictionaries. For
textual statements, it should be in a format suitable for the
dialect's paramstyle (i.e. dict or list of dicts for non
positional, list or list of lists/tuples for positional).
isinsert
True if the statement is an INSERT.
isupdate
True if the statement is an UPDATE.
should_autocommit
True if the statement is a "committable" statement.
postfetch_cols
a list of Column objects for which a server-side default or
inline SQL expression value was fired off. Applies to inserts
and updates.
"""
def create_cursor(self):
"""Return a new cursor generated from this ExecutionContext's
connection.
Some dialects may wish to change the behavior of
connection.cursor(), such as postgresql which may return a PG
"server side" cursor.
"""
raise NotImplementedError()
def pre_exec(self):
"""Called before an execution of a compiled statement.
If a compiled statement was passed to this ExecutionContext,
the `statement` and `parameters` datamembers must be
initialized after this statement is complete.
"""
raise NotImplementedError()
def post_exec(self):
"""Called after the execution of a compiled statement.
If a compiled statement was passed to this ExecutionContext,
the `last_insert_ids`, `last_inserted_params`, etc.
datamembers should be available after this method completes.
"""
raise NotImplementedError()
def result(self):
"""Return a result object corresponding to this ExecutionContext.
Returns a ResultProxy.
"""
raise NotImplementedError()
def handle_dbapi_exception(self, e):
"""Receive a DBAPI exception which occurred upon execute, result
fetch, etc."""
raise NotImplementedError()
def should_autocommit_text(self, statement):
"""Parse the given textual statement and return True if it refers to
a "committable" statement"""
raise NotImplementedError()
def lastrow_has_defaults(self):
"""Return True if the last INSERT or UPDATE row contained
inlined or database-side defaults.
"""
raise NotImplementedError()
def get_rowcount(self):
"""Return the number of rows produced (by a SELECT query)
or affected (by an INSERT/UPDATE/DELETE statement).
Note that this row count may not be properly implemented
in some dialects; this is indicated by the
``supports_sane_rowcount`` and ``supports_sane_multi_rowcount``
dialect attributes.
"""
raise NotImplementedError()
class Compiled(object):
"""Represent a compiled SQL or DDL expression.
The ``__str__`` method of the ``Compiled`` object should produce
the actual text of the statement. ``Compiled`` objects are
specific to their underlying database dialect, and also may
or may not be specific to the columns referenced within a
particular set of bind parameters. In no case should the
``Compiled`` object be dependent on the actual values of those
bind parameters, even though it may reference those values as
defaults.
"""
def __init__(self, dialect, statement, bind=None):
"""Construct a new ``Compiled`` object.
:param dialect: ``Dialect`` to compile against.
:param statement: ``ClauseElement`` to be compiled.
:param bind: Optional Engine or Connection to compile this
statement against.
"""
self.dialect = dialect
self.bind = bind
if statement is not None:
self.statement = statement
self.can_execute = statement.supports_execution
self.string = self.process(self.statement)
@util.deprecated("0.7", ":class:`.Compiled` objects now compile "
"within the constructor.")
def compile(self):
"""Produce the internal string representation of this element."""
pass
@property
def sql_compiler(self):
"""Return a Compiled that is capable of processing SQL expressions.
If this compiler is one, it would likely just return 'self'.
"""
raise NotImplementedError()
def process(self, obj, **kwargs):
return obj._compiler_dispatch(self, **kwargs)
def __str__(self):
"""Return the string text of the generated SQL or DDL."""
return self.string or ''
def construct_params(self, params=None):
"""Return the bind params for this compiled object.
:param params: a dict of string/object pairs whos values will
override bind values compiled in to the
statement.
"""
raise NotImplementedError()
@property
def params(self):
"""Return the bind params for this compiled object."""
return self.construct_params()
def execute(self, *multiparams, **params):
"""Execute this compiled object."""
e = self.bind
if e is None:
raise exc.UnboundExecutionError(
"This Compiled object is not bound to any Engine "
"or Connection.")
return e._execute_compiled(self, multiparams, params)
def scalar(self, *multiparams, **params):
"""Execute this compiled object and return the result's
scalar value."""
return self.execute(*multiparams, **params).scalar()
class TypeCompiler(object):
"""Produces DDL specification for TypeEngine objects."""
def __init__(self, dialect):
self.dialect = dialect
def process(self, type_):
return type_._compiler_dispatch(self)
class Connectable(object):
"""Interface for an object which supports execution of SQL constructs.
The two implementations of :class:`.Connectable` are :class:`.Connection` and
:class:`.Engine`.
Connectable must also implement the 'dialect' member which references a
:class:`.Dialect` instance.
"""
def connect(self, **kwargs):
"""Return a :class:`.Connection` object.
Depending on context, this may be ``self`` if this object
is already an instance of :class:`.Connection`, or a newly
procured :class:`.Connection` if this object is an instance
of :class:`.Engine`.
"""
def contextual_connect(self):
"""Return a :class:`.Connection` object which may be part of an ongoing
context.
Depending on context, this may be ``self`` if this object
is already an instance of :class:`.Connection`, or a newly
procured :class:`.Connection` if this object is an instance
of :class:`.Engine`.
"""
raise NotImplementedError()
@util.deprecated("0.7", "Use the create() method on the given schema "
"object directly, i.e. :meth:`.Table.create`, "
":meth:`.Index.create`, :meth:`.MetaData.create_all`")
def create(self, entity, **kwargs):
"""Emit CREATE statements for the given schema entity."""
raise NotImplementedError()
@util.deprecated("0.7", "Use the drop() method on the given schema "
"object directly, i.e. :meth:`.Table.drop`, "
":meth:`.Index.drop`, :meth:`.MetaData.drop_all`")
def drop(self, entity, **kwargs):
"""Emit DROP statements for the given schema entity."""
raise NotImplementedError()
def execute(self, object, *multiparams, **params):
"""Executes the given construct and returns a :class:`.ResultProxy`."""
raise NotImplementedError()
def scalar(self, object, *multiparams, **params):
"""Executes and returns the first column of the first row.
The underlying cursor is closed after execution.
"""
raise NotImplementedError()
def _run_visitor(self, visitorcallable, element,
**kwargs):
raise NotImplementedError()
def _execute_clauseelement(self, elem, multiparams=None, params=None):
raise NotImplementedError()
class Connection(Connectable):
"""Provides high-level functionality for a wrapped DB-API connection.
Provides execution support for string-based SQL statements as well as
:class:`.ClauseElement`, :class:`.Compiled` and :class:`.DefaultGenerator`
objects. Provides a :meth:`begin` method to return :class:`.Transaction`
objects.
The Connection object is **not** thread-safe. While a Connection can be
shared among threads using properly synchronized access, it is still
possible that the underlying DBAPI connection may not support shared
access between threads. Check the DBAPI documentation for details.
The Connection object represents a single dbapi connection checked out
from the connection pool. In this state, the connection pool has no affect
upon the connection, including its expiration or timeout state. For the
connection pool to properly manage connections, connections should be
returned to the connection pool (i.e. ``connection.close()``) whenever the
connection is not in use.
.. index::
single: thread safety; Connection
"""
def __init__(self, engine, connection=None, close_with_result=False,
_branch=False, _execution_options=None):
"""Construct a new Connection.
The constructor here is not public and is only called only by an
:class:`.Engine`. See :meth:`.Engine.connect` and
:meth:`.Engine.contextual_connect` methods.
"""
self.engine = engine
self.dialect = engine.dialect
self.__connection = connection or engine.raw_connection()
self.__transaction = None
self.should_close_with_result = close_with_result
self.__savepoint_seq = 0
self.__branch = _branch
self.__invalid = False
self._has_events = engine._has_events
self._echo = self.engine._should_log_info()
if _execution_options:
self._execution_options =\
engine._execution_options.union(_execution_options)
else:
self._execution_options = engine._execution_options
def _branch(self):
"""Return a new Connection which references this Connection's
engine and connection; but does not have close_with_result enabled,
and also whose close() method does nothing.
This is used to execute "sub" statements within a single execution,
usually an INSERT statement.
"""
return self.engine._connection_cls(
self.engine,
self.__connection, _branch=True)
def _clone(self):
"""Create a shallow copy of this Connection.
"""
c = self.__class__.__new__(self.__class__)
c.__dict__ = self.__dict__.copy()
return c
def execution_options(self, **opt):
""" Set non-SQL options for the connection which take effect
during execution.
The method returns a copy of this :class:`.Connection` which references
the same underlying DBAPI connection, but also defines the given
execution options which will take effect for a call to
:meth:`execute`. As the new :class:`.Connection` references the same
underlying resource, it is probably best to ensure that the copies
would be discarded immediately, which is implicit if used as in::
result = connection.execution_options(stream_results=True).\\
execute(stmt)
:meth:`.Connection.execution_options` accepts all options as those
accepted by :meth:`.Executable.execution_options`. Additionally,
it includes options that are applicable only to
:class:`.Connection`.
:param autocommit: Available on: Connection, statement.
When True, a COMMIT will be invoked after execution
when executed in 'autocommit' mode, i.e. when an explicit
transaction is not begun on the connection. Note that DBAPI
connections by default are always in a transaction - SQLAlchemy uses
rules applied to different kinds of statements to determine if
COMMIT will be invoked in order to provide its "autocommit" feature.
Typically, all INSERT/UPDATE/DELETE statements as well as
CREATE/DROP statements have autocommit behavior enabled; SELECT
constructs do not. Use this option when invoking a SELECT or other
specific SQL construct where COMMIT is desired (typically when
calling stored procedures and such), and an explicit
transaction is not in progress.
:param compiled_cache: Available on: Connection.
A dictionary where :class:`.Compiled` objects
will be cached when the :class:`.Connection` compiles a clause
expression into a :class:`.Compiled` object.
It is the user's responsibility to
manage the size of this dictionary, which will have keys
corresponding to the dialect, clause element, the column
names within the VALUES or SET clause of an INSERT or UPDATE,
as well as the "batch" mode for an INSERT or UPDATE statement.
The format of this dictionary is not guaranteed to stay the
same in future releases.
Note that the ORM makes use of its own "compiled" caches for
some operations, including flush operations. The caching
used by the ORM internally supersedes a cache dictionary
specified here.
:param isolation_level: Available on: Connection.
Set the transaction isolation level for
the lifespan of this connection. Valid values include
those string values accepted by the ``isolation_level``
parameter passed to :func:`.create_engine`, and are
database specific, including those for :ref:`sqlite_toplevel`,
:ref:`postgresql_toplevel` - see those dialect's documentation
for further info.
Note that this option necessarily affects the underying
DBAPI connection for the lifespan of the originating
:class:`.Connection`, and is not per-execution. This
setting is not removed until the underying DBAPI connection
is returned to the connection pool, i.e.
the :meth:`.Connection.close` method is called.
:param stream_results: Available on: Connection, statement.
Indicate to the dialect that results should be
"streamed" and not pre-buffered, if possible. This is a limitation
of many DBAPIs. The flag is currently understood only by the
psycopg2 dialect.
"""
c = self._clone()
c._execution_options = c._execution_options.union(opt)
if 'isolation_level' in opt:
c._set_isolation_level()
return c
def _set_isolation_level(self):
self.dialect.set_isolation_level(self.connection,
self._execution_options['isolation_level'])
self.connection._connection_record.finalize_callback = \
self.dialect.reset_isolation_level
@property
def closed(self):
"""Return True if this connection is closed."""
return not self.__invalid and '_Connection__connection' \
not in self.__dict__
@property
def invalidated(self):
"""Return True if this connection was invalidated."""
return self.__invalid
@property
def connection(self):
"The underlying DB-API connection managed by this Connection."
try:
return self.__connection
except AttributeError:
return self._revalidate_connection()
def _revalidate_connection(self):
if self.__invalid:
if self.__transaction is not None:
raise exc.InvalidRequestError(
"Can't reconnect until invalid "
"transaction is rolled back")
self.__connection = self.engine.raw_connection()
self.__invalid = False
return self.__connection
raise exc.ResourceClosedError("This Connection is closed")
@property
def _connection_is_valid(self):
# use getattr() for is_valid to support exceptions raised in
# dialect initializer, where the connection is not wrapped in
# _ConnectionFairy
return getattr(self.__connection, 'is_valid', False)
@property
def _still_open_and_connection_is_valid(self):
return \
not self.closed and \
not self.invalidated and \
getattr(self.__connection, 'is_valid', False)
@property
def info(self):
"""A collection of per-DB-API connection instance properties."""
return self.connection.info
def connect(self):
"""Returns self.
This ``Connectable`` interface method returns self, allowing
Connections to be used interchangably with Engines in most
situations that require a bind.
"""
return self
def contextual_connect(self, **kwargs):
"""Returns self.
This ``Connectable`` interface method returns self, allowing
Connections to be used interchangably with Engines in most
situations that require a bind.
"""
return self
def invalidate(self, exception=None):
"""Invalidate the underlying DBAPI connection associated with
this Connection.
The underlying DB-API connection is literally closed (if
possible), and is discarded. Its source connection pool will
typically lazily create a new connection to replace it.
Upon the next usage, this Connection will attempt to reconnect
to the pool with a new connection.
Transactions in progress remain in an "opened" state (even though the
actual transaction is gone); these must be explicitly rolled back
before a reconnect on this Connection can proceed. This is to prevent
applications from accidentally continuing their transactional
operations in a non-transactional state.
"""
if self.invalidated:
return
if self.closed:
raise exc.ResourceClosedError("This Connection is closed")
if self._connection_is_valid:
self.__connection.invalidate(exception)
del self.__connection
self.__invalid = True
def detach(self):
"""Detach the underlying DB-API connection from its connection pool.
This Connection instance will remain useable. When closed,
the DB-API connection will be literally closed and not
returned to its pool. The pool will typically lazily create a
new connection to replace the detached connection.
This method can be used to insulate the rest of an application
from a modified state on a connection (such as a transaction
isolation level or similar). Also see
:class:`~sqlalchemy.interfaces.PoolListener` for a mechanism to modify
connection state when connections leave and return to their
connection pool.
"""
self.__connection.detach()
def begin(self):
"""Begin a transaction and return a transaction handle.
The returned object is an instance of :class:`.Transaction`.
Repeated calls to ``begin`` on the same Connection will create
a lightweight, emulated nested transaction. Only the
outermost transaction may ``commit``. Calls to ``commit`` on
inner transactions are ignored. Any transaction in the
hierarchy may ``rollback``, however.
See also :meth:`.Connection.begin_nested`,
:meth:`.Connection.begin_twophase`.
"""
if self.__transaction is None:
self.__transaction = RootTransaction(self)
return self.__transaction
else:
return Transaction(self, self.__transaction)
def begin_nested(self):
"""Begin a nested transaction and return a transaction handle.
The returned object is an instance of :class:`.NestedTransaction`.
Nested transactions require SAVEPOINT support in the
underlying database. Any transaction in the hierarchy may
``commit`` and ``rollback``, however the outermost transaction
still controls the overall ``commit`` or ``rollback`` of the
transaction of a whole.
See also :meth:`.Connection.begin`,
:meth:`.Connection.begin_twophase`.
"""
if self.__transaction is None:
self.__transaction = RootTransaction(self)
else:
self.__transaction = NestedTransaction(self, self.__transaction)
return self.__transaction
def begin_twophase(self, xid=None):
"""Begin a two-phase or XA transaction and return a transaction
handle.
The returned object is an instance of :class:`.TwoPhaseTransaction`,
which in addition to the methods provided by
:class:`.Transaction`, also provides a :meth:`~.TwoPhaseTransaction.prepare`
method.
:param xid: the two phase transaction id. If not supplied, a
random id will be generated.
See also :meth:`.Connection.begin`,
:meth:`.Connection.begin_twophase`.
"""
if self.__transaction is not None:
raise exc.InvalidRequestError(
"Cannot start a two phase transaction when a transaction "
"is already in progress.")
if xid is None:
xid = self.engine.dialect.create_xid();
self.__transaction = TwoPhaseTransaction(self, xid)
return self.__transaction
def recover_twophase(self):
return self.engine.dialect.do_recover_twophase(self)
def rollback_prepared(self, xid, recover=False):
self.engine.dialect.do_rollback_twophase(self, xid, recover=recover)
def commit_prepared(self, xid, recover=False):
self.engine.dialect.do_commit_twophase(self, xid, recover=recover)
def in_transaction(self):
"""Return True if a transaction is in progress."""
return self.__transaction is not None
def _begin_impl(self):
if self._echo:
self.engine.logger.info("BEGIN (implicit)")
if self._has_events:
self.engine.dispatch.begin(self)
try:
self.engine.dialect.do_begin(self.connection)
except Exception, e:
self._handle_dbapi_exception(e, None, None, None, None)
raise
def _rollback_impl(self):
if self._has_events:
self.engine.dispatch.rollback(self)
if self._still_open_and_connection_is_valid:
if self._echo:
self.engine.logger.info("ROLLBACK")
try:
self.engine.dialect.do_rollback(self.connection)
self.__transaction = None
except Exception, e:
self._handle_dbapi_exception(e, None, None, None, None)
raise
else:
self.__transaction = None
def _commit_impl(self):
if self._has_events:
self.engine.dispatch.commit(self)
if self._echo:
self.engine.logger.info("COMMIT")
try:
self.engine.dialect.do_commit(self.connection)
self.__transaction = None
except Exception, e:
self._handle_dbapi_exception(e, None, None, None, None)
raise
def _savepoint_impl(self, name=None):
if self._has_events:
self.engine.dispatch.savepoint(self, name)
if name is None:
self.__savepoint_seq += 1
name = 'sa_savepoint_%s' % self.__savepoint_seq
if self._still_open_and_connection_is_valid:
self.engine.dialect.do_savepoint(self, name)
return name
def _rollback_to_savepoint_impl(self, name, context):
if self._has_events:
self.engine.dispatch.rollback_savepoint(self, name, context)
if self._still_open_and_connection_is_valid:
self.engine.dialect.do_rollback_to_savepoint(self, name)
self.__transaction = context
def _release_savepoint_impl(self, name, context):
if self._has_events:
self.engine.dispatch.release_savepoint(self, name, context)
if self._still_open_and_connection_is_valid:
self.engine.dialect.do_release_savepoint(self, name)
self.__transaction = context
def _begin_twophase_impl(self, xid):
if self._has_events:
self.engine.dispatch.begin_twophase(self, xid)
if self._still_open_and_connection_is_valid:
self.engine.dialect.do_begin_twophase(self, xid)
def _prepare_twophase_impl(self, xid):
if self._has_events:
self.engine.dispatch.prepare_twophase(self, xid)
if self._still_open_and_connection_is_valid:
assert isinstance(self.__transaction, TwoPhaseTransaction)
self.engine.dialect.do_prepare_twophase(self, xid)
def _rollback_twophase_impl(self, xid, is_prepared):
if self._has_events:
self.engine.dispatch.rollback_twophase(self, xid, is_prepared)
if self._still_open_and_connection_is_valid:
assert isinstance(self.__transaction, TwoPhaseTransaction)
self.engine.dialect.do_rollback_twophase(self, xid, is_prepared)
self.__transaction = None
def _commit_twophase_impl(self, xid, is_prepared):
if self._has_events:
self.engine.dispatch.commit_twophase(self, xid, is_prepared)
if self._still_open_and_connection_is_valid:
assert isinstance(self.__transaction, TwoPhaseTransaction)
self.engine.dialect.do_commit_twophase(self, xid, is_prepared)
self.__transaction = None
def _autorollback(self):
if not self.in_transaction():
self._rollback_impl()
def close(self):
"""Close this :class:`.Connection`.
This results in a release of the underlying database
resources, that is, the DBAPI connection referenced
internally. The DBAPI connection is typically restored
back to the connection-holding :class:`.Pool` referenced
by the :class:`.Engine` that produced this
:class:`.Connection`. Any transactional state present on
the DBAPI connection is also unconditionally released via
the DBAPI connection's ``rollback()`` method, regardless
of any :class:`.Transaction` object that may be
outstanding with regards to this :class:`.Connection`.
After :meth:`~.Connection.close` is called, the
:class:`.Connection` is permanently in a closed state,
and will allow no further operations.
"""
try:
conn = self.__connection
except AttributeError:
return
if not self.__branch:
conn.close()
self.__invalid = False
del self.__connection
self.__transaction = None
def scalar(self, object, *multiparams, **params):
"""Executes and returns the first column of the first row.
The underlying result/cursor is closed after execution.
"""
return self.execute(object, *multiparams, **params).scalar()
def execute(self, object, *multiparams, **params):
"""Executes the a SQL statement construct and returns a :class:`.ResultProxy`.
:param object: The statement to be executed. May be
one of:
* a plain string
* any :class:`.ClauseElement` construct that is also
a subclass of :class:`.Executable`, such as a
:func:`~.expression.select` construct
* a :class:`.FunctionElement`, such as that generated
by :attr:`.func`, will be automatically wrapped in
a SELECT statement, which is then executed.
* a :class:`.DDLElement` object
* a :class:`.DefaultGenerator` object
* a :class:`.Compiled` object
:param \*multiparams/\**params: represent bound parameter
values to be used in the execution. Typically,
the format is either a collection of one or more
dictionaries passed to \*multiparams::
conn.execute(
table.insert(),
{"id":1, "value":"v1"},
{"id":2, "value":"v2"}
)
...or individual key/values interpreted by \**params::
conn.execute(
table.insert(), id=1, value="v1"
)
In the case that a plain SQL string is passed, and the underlying
DBAPI accepts positional bind parameters, a collection of tuples
or individual values in \*multiparams may be passed::
conn.execute(
"INSERT INTO table (id, value) VALUES (?, ?)",
(1, "v1"), (2, "v2")
)
conn.execute(
"INSERT INTO table (id, value) VALUES (?, ?)",
1, "v1"
)
Note above, the usage of a question mark "?" or other
symbol is contingent upon the "paramstyle" accepted by the DBAPI
in use, which may be any of "qmark", "named", "pyformat", "format",
"numeric". See `pep-249 <http://www.python.org/dev/peps/pep-0249/>`_
for details on paramstyle.
To execute a textual SQL statement which uses bound parameters in a
DBAPI-agnostic way, use the :func:`~.expression.text` construct.
"""
for c in type(object).__mro__:
if c in Connection.executors:
return Connection.executors[c](
self,
object,
multiparams,
params)
else:
raise exc.InvalidRequestError(
"Unexecutable object type: %s" %
type(object))
def __distill_params(self, multiparams, params):
"""Given arguments from the calling form *multiparams, **params,
return a list of bind parameter structures, usually a list of
dictionaries.
In the case of 'raw' execution which accepts positional parameters,
it may be a list of tuples or lists.
"""
if not multiparams:
if params:
return [params]
else:
return []
elif len(multiparams) == 1:
zero = multiparams[0]
if isinstance(zero, (list, tuple)):
if not zero or hasattr(zero[0], '__iter__'):
return zero
else:
return [zero]
elif hasattr(zero, 'keys'):
return [zero]
else:
return [[zero]]
else:
if hasattr(multiparams[0], '__iter__'):
return multiparams
else:
return [multiparams]
def _execute_function(self, func, multiparams, params):
"""Execute a sql.FunctionElement object."""
return self._execute_clauseelement(func.select(),
multiparams, params)
def _execute_default(self, default, multiparams, params):
"""Execute a schema.ColumnDefault object."""
if self._has_events:
for fn in self.engine.dispatch.before_execute:
default, multiparams, params = \
fn(self, default, multiparams, params)
try:
try:
conn = self.__connection
except AttributeError:
conn = self._revalidate_connection()
dialect = self.dialect
ctx = dialect.execution_ctx_cls._init_default(
dialect, self, conn)
except Exception, e:
self._handle_dbapi_exception(e, None, None, None, None)
raise
ret = ctx._exec_default(default, None)
if self.should_close_with_result:
self.close()
if self._has_events:
self.engine.dispatch.after_execute(self,
default, multiparams, params, ret)
return ret
def _execute_ddl(self, ddl, multiparams, params):
"""Execute a schema.DDL object."""
if self._has_events:
for fn in self.engine.dispatch.before_execute:
ddl, multiparams, params = \
fn(self, ddl, multiparams, params)
dialect = self.dialect
compiled = ddl.compile(dialect=dialect)
ret = self._execute_context(
dialect,
dialect.execution_ctx_cls._init_ddl,
compiled,
None,
compiled
)
if self._has_events:
self.engine.dispatch.after_execute(self,
ddl, multiparams, params, ret)
return ret
def _execute_clauseelement(self, elem, multiparams, params):
"""Execute a sql.ClauseElement object."""
if self._has_events:
for fn in self.engine.dispatch.before_execute:
elem, multiparams, params = \
fn(self, elem, multiparams, params)
distilled_params = self.__distill_params(multiparams, params)
if distilled_params:
keys = distilled_params[0].keys()
else:
keys = []
dialect = self.dialect
if 'compiled_cache' in self._execution_options:
key = dialect, elem, tuple(keys), len(distilled_params) > 1
if key in self._execution_options['compiled_cache']:
compiled_sql = self._execution_options['compiled_cache'][key]
else:
compiled_sql = elem.compile(
dialect=dialect, column_keys=keys,
inline=len(distilled_params) > 1)
self._execution_options['compiled_cache'][key] = compiled_sql
else:
compiled_sql = elem.compile(
dialect=dialect, column_keys=keys,
inline=len(distilled_params) > 1)
ret = self._execute_context(
dialect,
dialect.execution_ctx_cls._init_compiled,
compiled_sql,
distilled_params,
compiled_sql, distilled_params
)
if self._has_events:
self.engine.dispatch.after_execute(self,
elem, multiparams, params, ret)
return ret
def _execute_compiled(self, compiled, multiparams, params):
"""Execute a sql.Compiled object."""
if self._has_events:
for fn in self.engine.dispatch.before_execute:
compiled, multiparams, params = \
fn(self, compiled, multiparams, params)
dialect = self.dialect
parameters=self.__distill_params(multiparams, params)
ret = self._execute_context(
dialect,
dialect.execution_ctx_cls._init_compiled,
compiled,
parameters,
compiled, parameters
)
if self._has_events:
self.engine.dispatch.after_execute(self,
compiled, multiparams, params, ret)
return ret
def _execute_text(self, statement, multiparams, params):
"""Execute a string SQL statement."""
if self._has_events:
for fn in self.engine.dispatch.before_execute:
statement, multiparams, params = \
fn(self, statement, multiparams, params)
dialect = self.dialect
parameters = self.__distill_params(multiparams, params)
ret = self._execute_context(
dialect,
dialect.execution_ctx_cls._init_statement,
statement,
parameters,
statement, parameters
)
if self._has_events:
self.engine.dispatch.after_execute(self,
statement, multiparams, params, ret)
return ret
def _execute_context(self, dialect, constructor,
statement, parameters,
*args):
"""Create an :class:`.ExecutionContext` and execute, returning
a :class:`.ResultProxy`."""
try:
try:
conn = self.__connection
except AttributeError:
conn = self._revalidate_connection()
context = constructor(dialect, self, conn, *args)
except Exception, e:
self._handle_dbapi_exception(e,
str(statement), parameters,
None, None)
raise
if context.compiled:
context.pre_exec()
cursor, statement, parameters = context.cursor, \
context.statement, \
context.parameters
if not context.executemany:
parameters = parameters[0]
if self._has_events:
for fn in self.engine.dispatch.before_cursor_execute:
statement, parameters = \
fn(self, cursor, statement, parameters,
context, context.executemany)
if self._echo:
self.engine.logger.info(statement)
self.engine.logger.info("%r", sql_util._repr_params(parameters, batches=10))
try:
if context.executemany:
self.dialect.do_executemany(
cursor,
statement,
parameters,
context)
else:
self.dialect.do_execute(
cursor,
statement,
parameters,
context)
except Exception, e:
self._handle_dbapi_exception(
e,
statement,
parameters,
cursor,
context)
raise
if self._has_events:
self.engine.dispatch.after_cursor_execute(self, cursor,
statement,
parameters,
context,
context.executemany)
if context.compiled:
context.post_exec()
if context.isinsert and not context.executemany:
context.post_insert()
# create a resultproxy, get rowcount/implicit RETURNING
# rows, close cursor if no further results pending
result = context.get_result_proxy()
if context.isinsert:
if context._is_implicit_returning:
context._fetch_implicit_returning(result)
result.close(_autoclose_connection=False)
elif not context._is_explicit_returning:
result.close(_autoclose_connection=False)
elif result._metadata is None:
# no results, get rowcount
# (which requires open cursor on some drivers
# such as kintersbasdb, mxodbc),
result.rowcount
result.close(_autoclose_connection=False)
if self.__transaction is None and context.should_autocommit:
self._commit_impl()
if result.closed and self.should_close_with_result:
self.close()
return result
def _cursor_execute(self, cursor, statement, parameters):
"""Execute a statement + params on the given cursor.
Adds appropriate logging and exception handling.
This method is used by DefaultDialect for special-case
executions, such as for sequences and column defaults.
The path of statement execution in the majority of cases
terminates at _execute_context().
"""
if self._echo:
self.engine.logger.info(statement)
self.engine.logger.info("%r", parameters)
try:
self.dialect.do_execute(
cursor,
statement,
parameters)
except Exception, e:
self._handle_dbapi_exception(
e,
statement,
parameters,
cursor,
None)
raise
def _safe_close_cursor(self, cursor):
"""Close the given cursor, catching exceptions
and turning into log warnings.
"""
try:
cursor.close()
except Exception, e:
try:
ex_text = str(e)
except TypeError:
ex_text = repr(e)
self.connection._logger.warn("Error closing cursor: %s", ex_text)
if isinstance(e, (SystemExit, KeyboardInterrupt)):
raise
def _handle_dbapi_exception(self,
e,
statement,
parameters,
cursor,
context):
if getattr(self, '_reentrant_error', False):
# Py3K
#raise exc.DBAPIError.instance(statement, parameters, e,
# self.dialect.dbapi.Error) from e
# Py2K
raise exc.DBAPIError.instance(statement,
parameters,
e,
self.dialect.dbapi.Error), \
None, sys.exc_info()[2]
# end Py2K
self._reentrant_error = True
try:
# non-DBAPI error - if we already got a context,
# or theres no string statement, don't wrap it
should_wrap = isinstance(e, self.dialect.dbapi.Error) or \
(statement is not None and context is None)
if should_wrap and context:
context.handle_dbapi_exception(e)
is_disconnect = isinstance(e, self.dialect.dbapi.Error) and \
self.dialect.is_disconnect(e, self.__connection, cursor)
if is_disconnect:
self.invalidate(e)
self.engine.dispose()
else:
if cursor:
self._safe_close_cursor(cursor)
self._autorollback()
if self.should_close_with_result:
self.close()
if not should_wrap:
return
# Py3K
#raise exc.DBAPIError.instance(
# statement,
# parameters,
# e,
# self.dialect.dbapi.Error,
# connection_invalidated=is_disconnect) \
# from e
# Py2K
raise exc.DBAPIError.instance(
statement,
parameters,
e,
self.dialect.dbapi.Error,
connection_invalidated=is_disconnect), \
None, sys.exc_info()[2]
# end Py2K
finally:
del self._reentrant_error
# poor man's multimethod/generic function thingy
executors = {
expression.FunctionElement: _execute_function,
expression.ClauseElement: _execute_clauseelement,
Compiled: _execute_compiled,
schema.SchemaItem: _execute_default,
schema.DDLElement: _execute_ddl,
basestring: _execute_text
}
@util.deprecated("0.7", "Use the create() method on the given schema "
"object directly, i.e. :meth:`.Table.create`, "
":meth:`.Index.create`, :meth:`.MetaData.create_all`")
def create(self, entity, **kwargs):
"""Emit CREATE statements for the given schema entity."""
return self.engine.create(entity, connection=self, **kwargs)
@util.deprecated("0.7", "Use the drop() method on the given schema "
"object directly, i.e. :meth:`.Table.drop`, "
":meth:`.Index.drop`, :meth:`.MetaData.drop_all`")
def drop(self, entity, **kwargs):
"""Emit DROP statements for the given schema entity."""
return self.engine.drop(entity, connection=self, **kwargs)
@util.deprecated("0.7", "Use autoload=True with :class:`.Table`, "
"or use the :class:`.Inspector` object.")
def reflecttable(self, table, include_columns=None):
"""Load table description from the database.
Given a :class:`.Table` object, reflect its columns and
properties from the database, populating the given :class:`.Table`
object with attributes.. If include_columns (a list or
set) is specified, limit the autoload to the given column
names.
The default implementation uses the
:class:`.Inspector` interface to
provide the output, building upon the granular table/column/
constraint etc. methods of :class:`.Dialect`.
"""
return self.engine.reflecttable(table, self, include_columns)
def default_schema_name(self):
return self.engine.dialect.get_default_schema_name(self)
def transaction(self, callable_, *args, **kwargs):
"""Execute the given function within a transaction boundary.
The function is passed this :class:`.Connection`
as the first argument, followed by the given \*args and \**kwargs.
This is a shortcut for explicitly invoking
:meth:`.Connection.begin`, calling :meth:`.Transaction.commit`
upon success or :meth:`.Transaction.rollback` upon an
exception raise::
def do_something(conn, x, y):
conn.execute("some statement", {'x':x, 'y':y})
conn.transaction(do_something, 5, 10)
Note that context managers (i.e. the ``with`` statement)
present a more modern way of accomplishing the above,
using the :class:`.Transaction` object as a base::
with conn.begin():
conn.execute("some statement", {'x':5, 'y':10})
One advantage to the :meth:`.Connection.transaction`
method is that the same method is also available
on :class:`.Engine` as :meth:`.Engine.transaction` -
this method procures a :class:`.Connection` and then
performs the same operation, allowing equivalent
usage with either a :class:`.Connection` or :class:`.Engine`
without needing to know what kind of object
it is.
"""
trans = self.begin()
try:
ret = self.run_callable(callable_, *args, **kwargs)
trans.commit()
return ret
except:
trans.rollback()
raise
def run_callable(self, callable_, *args, **kwargs):
"""Given a callable object or function, execute it, passing
a :class:`.Connection` as the first argument.
The given \*args and \**kwargs are passed subsequent
to the :class:`.Connection` argument.
This function, along with :meth:`.Engine.run_callable`,
allows a function to be run with a :class:`.Connection`
or :class:`.Engine` object without the need to know
which one is being dealt with.
"""
return callable_(self, *args, **kwargs)
def _run_visitor(self, visitorcallable, element, **kwargs):
visitorcallable(self.dialect, self,
**kwargs).traverse_single(element)
class Transaction(object):
"""Represent a database transaction in progress.
The :class:`.Transaction` object is procured by
calling the :meth:`~.Connection.begin` method of
:class:`.Connection`::
from sqlalchemy import create_engine
engine = create_engine("postgresql://scott:tiger@localhost/test")
connection = engine.connect()
trans = connection.begin()
connection.execute("insert into x (a, b) values (1, 2)")
trans.commit()
The object provides :meth:`.rollback` and :meth:`.commit`
methods in order to control transaction boundaries. It
also implements a context manager interface so that
the Python ``with`` statement can be used with the
:meth:`.Connection.begin` method::
with connection.begin():
connection.execute("insert into x (a, b) values (1, 2)")
The Transaction object is **not** threadsafe.
See also: :meth:`.Connection.begin`, :meth:`.Connection.begin_twophase`,
:meth:`.Connection.begin_nested`.
.. index::
single: thread safety; Transaction
"""
def __init__(self, connection, parent):
self.connection = connection
self._parent = parent or self
self.is_active = True
def close(self):
"""Close this :class:`.Transaction`.
If this transaction is the base transaction in a begin/commit
nesting, the transaction will rollback(). Otherwise, the
method returns.
This is used to cancel a Transaction without affecting the scope of
an enclosing transaction.
"""
if not self._parent.is_active:
return
if self._parent is self:
self.rollback()
def rollback(self):
"""Roll back this :class:`.Transaction`.
"""
if not self._parent.is_active:
return
self._do_rollback()
self.is_active = False
def _do_rollback(self):
self._parent.rollback()
def commit(self):
"""Commit this :class:`.Transaction`."""
if not self._parent.is_active:
raise exc.InvalidRequestError("This transaction is inactive")
self._do_commit()
self.is_active = False
def _do_commit(self):
pass
def __enter__(self):
return self
def __exit__(self, type, value, traceback):
if type is None and self.is_active:
try:
self.commit()
except:
self.rollback()
raise
else:
self.rollback()
class RootTransaction(Transaction):
def __init__(self, connection):
super(RootTransaction, self).__init__(connection, None)
self.connection._begin_impl()
def _do_rollback(self):
if self.is_active:
self.connection._rollback_impl()
def _do_commit(self):
if self.is_active:
self.connection._commit_impl()
class NestedTransaction(Transaction):
"""Represent a 'nested', or SAVEPOINT transaction.
A new :class:`.NestedTransaction` object may be procured
using the :meth:`.Connection.begin_nested` method.
The interface is the same as that of :class:`.Transaction`.
"""
def __init__(self, connection, parent):
super(NestedTransaction, self).__init__(connection, parent)
self._savepoint = self.connection._savepoint_impl()
def _do_rollback(self):
if self.is_active:
self.connection._rollback_to_savepoint_impl(
self._savepoint, self._parent)
def _do_commit(self):
if self.is_active:
self.connection._release_savepoint_impl(
self._savepoint, self._parent)
class TwoPhaseTransaction(Transaction):
"""Represent a two-phase transaction.
A new :class:`.TwoPhaseTransaction` object may be procured
using the :meth:`.Connection.begin_twophase` method.
The interface is the same as that of :class:`.Transaction`
with the addition of the :meth:`prepare` method.
"""
def __init__(self, connection, xid):
super(TwoPhaseTransaction, self).__init__(connection, None)
self._is_prepared = False
self.xid = xid
self.connection._begin_twophase_impl(self.xid)
def prepare(self):
"""Prepare this :class:`.TwoPhaseTransaction`.
After a PREPARE, the transaction can be committed.
"""
if not self._parent.is_active:
raise exc.InvalidRequestError("This transaction is inactive")
self.connection._prepare_twophase_impl(self.xid)
self._is_prepared = True
def _do_rollback(self):
self.connection._rollback_twophase_impl(self.xid, self._is_prepared)
def _do_commit(self):
self.connection._commit_twophase_impl(self.xid, self._is_prepared)
class Engine(Connectable, log.Identified):
"""
Connects a :class:`~sqlalchemy.pool.Pool` and
:class:`~sqlalchemy.engine.base.Dialect` together to provide a source
of database connectivity and behavior.
An :class:`.Engine` object is instantiated publically using the
:func:`~sqlalchemy.create_engine` function.
See also:
:ref:`engines_toplevel`
:ref:`connections_toplevel`
"""
_execution_options = util.immutabledict()
_has_events = False
_connection_cls = Connection
def __init__(self, pool, dialect, url,
logging_name=None, echo=None, proxy=None,
execution_options=None
):
self.pool = pool
self.url = url
self.dialect = dialect
if logging_name:
self.logging_name = logging_name
self.echo = echo
self.engine = self
log.instance_logger(self, echoflag=echo)
if proxy:
interfaces.ConnectionProxy._adapt_listener(self, proxy)
if execution_options:
if 'isolation_level' in execution_options:
raise exc.ArgumentError(
"'isolation_level' execution option may "
"only be specified on Connection.execution_options(). "
"To set engine-wide isolation level, "
"use the isolation_level argument to create_engine()."
)
self.update_execution_options(**execution_options)
dispatch = event.dispatcher(events.ConnectionEvents)
def update_execution_options(self, **opt):
"""Update the default execution_options dictionary
of this :class:`.Engine`.
The given keys/values in \**opt are added to the
default execution options that will be used for
all connections. The initial contents of this dictionary
can be sent via the ``execution_options`` paramter
to :func:`.create_engine`.
See :meth:`.Connection.execution_options` for more
details on execution options.
"""
self._execution_options = \
self._execution_options.union(opt)
@property
def name(self):
"""String name of the :class:`~sqlalchemy.engine.Dialect` in use by
this ``Engine``."""
return self.dialect.name
@property
def driver(self):
"""Driver name of the :class:`~sqlalchemy.engine.Dialect` in use by
this ``Engine``."""
return self.dialect.driver
echo = log.echo_property()
def __repr__(self):
return 'Engine(%s)' % str(self.url)
def dispose(self):
"""Dispose of the connection pool used by this :class:`.Engine`.
A new connection pool is created immediately after the old one has
been disposed. This new pool, like all SQLAlchemy connection pools,
does not make any actual connections to the database until one is
first requested.
This method has two general use cases:
* When a dropped connection is detected, it is assumed that all
connections held by the pool are potentially dropped, and
the entire pool is replaced.
* An application may want to use :meth:`dispose` within a test
suite that is creating multiple engines.
It is critical to note that :meth:`dispose` does **not** guarantee
that the application will release all open database connections - only
those connections that are checked into the pool are closed.
Connections which remain checked out or have been detached from
the engine are not affected.
"""
self.pool.dispose()
self.pool = self.pool.recreate()
@util.deprecated("0.7", "Use the create() method on the given schema "
"object directly, i.e. :meth:`.Table.create`, "
":meth:`.Index.create`, :meth:`.MetaData.create_all`")
def create(self, entity, connection=None, **kwargs):
"""Emit CREATE statements for the given schema entity."""
from sqlalchemy.engine import ddl
self._run_visitor(ddl.SchemaGenerator, entity,
connection=connection, **kwargs)
@util.deprecated("0.7", "Use the drop() method on the given schema "
"object directly, i.e. :meth:`.Table.drop`, "
":meth:`.Index.drop`, :meth:`.MetaData.drop_all`")
def drop(self, entity, connection=None, **kwargs):
"""Emit DROP statements for the given schema entity."""
from sqlalchemy.engine import ddl
self._run_visitor(ddl.SchemaDropper, entity,
connection=connection, **kwargs)
def _execute_default(self, default):
connection = self.contextual_connect()
try:
return connection._execute_default(default, (), {})
finally:
connection.close()
@property
@util.deprecated("0.7",
"Use :attr:`~sqlalchemy.sql.expression.func` to create function constructs.")
def func(self):
return expression._FunctionGenerator(bind=self)
@util.deprecated("0.7",
"Use :func:`.expression.text` to create text constructs.")
def text(self, text, *args, **kwargs):
"""Return a :func:`~sqlalchemy.sql.expression.text` construct,
bound to this engine.
This is equivalent to::
text("SELECT * FROM table", bind=engine)
"""
return expression.text(text, bind=self, *args, **kwargs)
def _run_visitor(self, visitorcallable, element,
connection=None, **kwargs):
if connection is None:
conn = self.contextual_connect(close_with_result=False)
else:
conn = connection
try:
conn._run_visitor(visitorcallable, element, **kwargs)
finally:
if connection is None:
conn.close()
def transaction(self, callable_, *args, **kwargs):
"""Execute the given function within a transaction boundary.
The function is passed a newly procured
:class:`.Connection` as the first argument, followed by
the given \*args and \**kwargs. The :class:`.Connection`
is then closed (returned to the pool) when the operation
is complete.
This method can be used interchangeably with
:meth:`.Connection.transaction`. See that method for
more details on usage as well as a modern alternative
using context managers (i.e. the ``with`` statement).
"""
conn = self.contextual_connect()
try:
return conn.transaction(callable_, *args, **kwargs)
finally:
conn.close()
def run_callable(self, callable_, *args, **kwargs):
"""Given a callable object or function, execute it, passing
a :class:`.Connection` as the first argument.
The given \*args and \**kwargs are passed subsequent
to the :class:`.Connection` argument.
This function, along with :meth:`.Connection.run_callable`,
allows a function to be run with a :class:`.Connection`
or :class:`.Engine` object without the need to know
which one is being dealt with.
"""
conn = self.contextual_connect()
try:
return conn.run_callable(callable_, *args, **kwargs)
finally:
conn.close()
def execute(self, statement, *multiparams, **params):
"""Executes the given construct and returns a :class:`.ResultProxy`.
The arguments are the same as those used by
:meth:`.Connection.execute`.
Here, a :class:`.Connection` is acquired using the
:meth:`~.Engine.contextual_connect` method, and the statement executed
with that connection. The returned :class:`.ResultProxy` is flagged
such that when the :class:`.ResultProxy` is exhausted and its
underlying cursor is closed, the :class:`.Connection` created here
will also be closed, which allows its associated DBAPI connection
resource to be returned to the connection pool.
"""
connection = self.contextual_connect(close_with_result=True)
return connection.execute(statement, *multiparams, **params)
def scalar(self, statement, *multiparams, **params):
return self.execute(statement, *multiparams, **params).scalar()
def _execute_clauseelement(self, elem, multiparams=None, params=None):
connection = self.contextual_connect(close_with_result=True)
return connection._execute_clauseelement(elem, multiparams, params)
def _execute_compiled(self, compiled, multiparams, params):
connection = self.contextual_connect(close_with_result=True)
return connection._execute_compiled(compiled, multiparams, params)
def connect(self, **kwargs):
"""Return a new :class:`.Connection` object.
The :class:`.Connection` object is a facade that uses a DBAPI connection internally
in order to communicate with the database. This connection is procured
from the connection-holding :class:`.Pool` referenced by this :class:`.Engine`.
When the :meth:`~.Connection.close` method of the :class:`.Connection` object is called,
the underlying DBAPI connection is then returned to the connection pool,
where it may be used again in a subsequent call to :meth:`~.Engine.connect`.
"""
return self._connection_cls(self, **kwargs)
def contextual_connect(self, close_with_result=False, **kwargs):
"""Return a :class:`.Connection` object which may be part of some ongoing context.
By default, this method does the same thing as :meth:`.Engine.connect`.
Subclasses of :class:`.Engine` may override this method
to provide contextual behavior.
:param close_with_result: When True, the first :class:`.ResultProxy` created
by the :class:`.Connection` will call the :meth:`.Connection.close` method
of that connection as soon as any pending result rows are exhausted.
This is used to supply the "connectionless execution" behavior provided
by the :meth:`.Engine.execute` method.
"""
return self._connection_cls(self,
self.pool.connect(),
close_with_result=close_with_result,
**kwargs)
def table_names(self, schema=None, connection=None):
"""Return a list of all table names available in the database.
:param schema: Optional, retrieve names from a non-default schema.
:param connection: Optional, use a specified connection. Default is
the ``contextual_connect`` for this ``Engine``.
"""
if connection is None:
conn = self.contextual_connect()
else:
conn = connection
if not schema:
schema = self.dialect.default_schema_name
try:
return self.dialect.get_table_names(conn, schema)
finally:
if connection is None:
conn.close()
@util.deprecated("0.7", "Use autoload=True with :class:`.Table`, "
"or use the :class:`.Inspector` object.")
def reflecttable(self, table, connection=None, include_columns=None):
"""Load table description from the database.
Uses the given :class:`.Connection`, or if None produces
its own :class:`.Connection`, and passes the ``table``
and ``include_columns`` arguments onto that
:class:`.Connection` object's :meth:`.Connection.reflecttable`
method. The :class:`.Table` object is then populated
with new attributes.
"""
if connection is None:
conn = self.contextual_connect()
else:
conn = connection
try:
self.dialect.reflecttable(conn, table, include_columns)
finally:
if connection is None:
conn.close()
def has_table(self, table_name, schema=None):
return self.run_callable(self.dialect.has_table, table_name, schema)
def raw_connection(self):
"""Return a "raw" DBAPI connection from the connection pool.
The returned object is a proxied version of the DBAPI
connection object used by the underlying driver in use.
The object will have all the same behavior as the real DBAPI
connection, except that its ``close()`` method will result in the
connection being returned to the pool, rather than being closed
for real.
This method provides direct DBAPI connection access for
special situations. In most situations, the :class:`.Connection`
object should be used, which is procured using the
:meth:`.Engine.connect` method.
"""
return self.pool.unique_connection()
# This reconstructor is necessary so that pickles with the C extension or
# without use the same Binary format.
try:
# We need a different reconstructor on the C extension so that we can
# add extra checks that fields have correctly been initialized by
# __setstate__.
from sqlalchemy.cresultproxy import safe_rowproxy_reconstructor
# The extra function embedding is needed so that the
# reconstructor function has the same signature whether or not
# the extension is present.
def rowproxy_reconstructor(cls, state):
return safe_rowproxy_reconstructor(cls, state)
except ImportError:
def rowproxy_reconstructor(cls, state):
obj = cls.__new__(cls)
obj.__setstate__(state)
return obj
try:
from sqlalchemy.cresultproxy import BaseRowProxy
except ImportError:
class BaseRowProxy(object):
__slots__ = ('_parent', '_row', '_processors', '_keymap')
def __init__(self, parent, row, processors, keymap):
"""RowProxy objects are constructed by ResultProxy objects."""
self._parent = parent
self._row = row
self._processors = processors
self._keymap = keymap
def __reduce__(self):
return (rowproxy_reconstructor,
(self.__class__, self.__getstate__()))
def values(self):
"""Return the values represented by this RowProxy as a list."""
return list(self)
def __iter__(self):
for processor, value in izip(self._processors, self._row):
if processor is None:
yield value
else:
yield processor(value)
def __len__(self):
return len(self._row)
def __getitem__(self, key):
try:
processor, index = self._keymap[key]
except KeyError:
processor, index = self._parent._key_fallback(key)
except TypeError:
if isinstance(key, slice):
l = []
for processor, value in izip(self._processors[key],
self._row[key]):
if processor is None:
l.append(value)
else:
l.append(processor(value))
return tuple(l)
else:
raise
if index is None:
raise exc.InvalidRequestError(
"Ambiguous column name '%s' in result set! "
"try 'use_labels' option on select statement." % key)
if processor is not None:
return processor(self._row[index])
else:
return self._row[index]
def __getattr__(self, name):
try:
# TODO: no test coverage here
return self[name]
except KeyError, e:
raise AttributeError(e.args[0])
class RowProxy(BaseRowProxy):
"""Proxy values from a single cursor row.
Mostly follows "ordered dictionary" behavior, mapping result
values to the string-based column name, the integer position of
the result in the row, as well as Column instances which can be
mapped to the original Columns that produced this result set (for
results that correspond to constructed SQL expressions).
"""
__slots__ = ()
def __contains__(self, key):
return self._parent._has_key(self._row, key)
def __getstate__(self):
return {
'_parent': self._parent,
'_row': tuple(self)
}
def __setstate__(self, state):
self._parent = parent = state['_parent']
self._row = state['_row']
self._processors = parent._processors
self._keymap = parent._keymap
__hash__ = None
def __eq__(self, other):
return other is self or other == tuple(self)
def __ne__(self, other):
return not self.__eq__(other)
def __repr__(self):
return repr(tuple(self))
def has_key(self, key):
"""Return True if this RowProxy contains the given key."""
return self._parent._has_key(self._row, key)
def items(self):
"""Return a list of tuples, each tuple containing a key/value pair."""
# TODO: no coverage here
return [(key, self[key]) for key in self.iterkeys()]
def keys(self):
"""Return the list of keys as strings represented by this RowProxy."""
return self._parent.keys
def iterkeys(self):
return iter(self._parent.keys)
def itervalues(self):
return iter(self)
try:
# Register RowProxy with Sequence,
# so sequence protocol is implemented
from collections import Sequence
Sequence.register(RowProxy)
except ImportError:
pass
class ResultMetaData(object):
"""Handle cursor.description, applying additional info from an execution
context."""
def __init__(self, parent, metadata):
self._processors = processors = []
# We do not strictly need to store the processor in the key mapping,
# though it is faster in the Python version (probably because of the
# saved attribute lookup self._processors)
self._keymap = keymap = {}
self.keys = []
context = parent.context
dialect = context.dialect
typemap = dialect.dbapi_type_map
for i, rec in enumerate(metadata):
colname = rec[0]
coltype = rec[1]
if dialect.description_encoding:
colname = dialect._description_decoder(colname)
if context.result_map:
try:
name, obj, type_ = context.result_map[colname.lower()]
except KeyError:
name, obj, type_ = \
colname, None, typemap.get(coltype, types.NULLTYPE)
else:
name, obj, type_ = \
colname, None, typemap.get(coltype, types.NULLTYPE)
processor = type_._cached_result_processor(dialect, coltype)
processors.append(processor)
rec = (processor, i)
# indexes as keys. This is only needed for the Python version of
# RowProxy (the C version uses a faster path for integer indexes).
keymap[i] = rec
# Column names as keys
if keymap.setdefault(name.lower(), rec) is not rec:
# We do not raise an exception directly because several
# columns colliding by name is not a problem as long as the
# user does not try to access them (ie use an index directly,
# or the more precise ColumnElement)
keymap[name.lower()] = (processor, None)
if dialect.requires_name_normalize:
colname = dialect.normalize_name(colname)
self.keys.append(colname)
if obj:
for o in obj:
keymap[o] = rec
if parent._echo:
context.engine.logger.debug(
"Col %r", tuple(x[0] for x in metadata))
def _set_keymap_synonym(self, name, origname):
"""Set a synonym for the given name.
Some dialects (SQLite at the moment) may use this to
adjust the column names that are significant within a
row.
"""
rec = (processor, i) = self._keymap[origname.lower()]
if self._keymap.setdefault(name, rec) is not rec:
self._keymap[name] = (processor, None)
def _key_fallback(self, key, raiseerr=True):
map = self._keymap
result = None
if isinstance(key, basestring):
result = map.get(key.lower())
# fallback for targeting a ColumnElement to a textual expression
# this is a rare use case which only occurs when matching text()
# constructs to ColumnElements, and after a pickle/unpickle roundtrip
elif isinstance(key, expression.ColumnElement):
if key._label and key._label.lower() in map:
result = map[key._label.lower()]
elif hasattr(key, 'name') and key.name.lower() in map:
result = map[key.name.lower()]
if result is None:
if raiseerr:
raise exc.NoSuchColumnError(
"Could not locate column in row for column '%s'" %
expression._string_or_unprintable(key))
else:
return None
else:
map[key] = result
return result
def _has_key(self, row, key):
if key in self._keymap:
return True
else:
return self._key_fallback(key, False) is not None
def __getstate__(self):
return {
'_pickled_keymap': dict(
(key, index)
for key, (processor, index) in self._keymap.iteritems()
if isinstance(key, (basestring, int))
),
'keys': self.keys
}
def __setstate__(self, state):
# the row has been processed at pickling time so we don't need any
# processor anymore
self._processors = [None for _ in xrange(len(state['keys']))]
self._keymap = keymap = {}
for key, index in state['_pickled_keymap'].iteritems():
keymap[key] = (None, index)
self.keys = state['keys']
self._echo = False
class ResultProxy(object):
"""Wraps a DB-API cursor object to provide easier access to row columns.
Individual columns may be accessed by their integer position,
case-insensitive column name, or by ``schema.Column``
object. e.g.::
row = fetchone()
col1 = row[0] # access via integer position
col2 = row['col2'] # access via name
col3 = row[mytable.c.mycol] # access via Column object.
``ResultProxy`` also handles post-processing of result column
data using ``TypeEngine`` objects, which are referenced from
the originating SQL statement that produced this result set.
"""
_process_row = RowProxy
out_parameters = None
_can_close_connection = False
def __init__(self, context):
self.context = context
self.dialect = context.dialect
self.closed = False
self.cursor = self._saved_cursor = context.cursor
self.connection = context.root_connection
self._echo = self.connection._echo and \
context.engine._should_log_debug()
self._init_metadata()
def _init_metadata(self):
metadata = self._cursor_description()
if metadata is None:
self._metadata = None
else:
self._metadata = ResultMetaData(self, metadata)
def keys(self):
"""Return the current set of string keys for rows."""
if self._metadata:
return self._metadata.keys
else:
return []
@util.memoized_property
def rowcount(self):
"""Return the 'rowcount' for this result.
The 'rowcount' reports the number of rows affected
by an UPDATE or DELETE statement. It has *no* other
uses and is not intended to provide the number of rows
present from a SELECT.
Note that this row count may not be properly implemented in some
dialects; this is indicated by
:meth:`~sqlalchemy.engine.base.ResultProxy.supports_sane_rowcount()`
and
:meth:`~sqlalchemy.engine.base.ResultProxy.supports_sane_multi_rowcount()`.
``rowcount()`` also may not work at this time for a statement that
uses ``returning()``.
"""
try:
return self.context.rowcount
except Exception, e:
self.connection._handle_dbapi_exception(
e, None, None, self.cursor, self.context)
raise
@property
def lastrowid(self):
"""return the 'lastrowid' accessor on the DBAPI cursor.
This is a DBAPI specific method and is only functional
for those backends which support it, for statements
where it is appropriate. It's behavior is not
consistent across backends.
Usage of this method is normally unnecessary; the
:attr:`~ResultProxy.inserted_primary_key` attribute provides a
tuple of primary key values for a newly inserted row,
regardless of database backend.
"""
try:
return self._saved_cursor.lastrowid
except Exception, e:
self.connection._handle_dbapi_exception(
e, None, None,
self._saved_cursor, self.context)
raise
@property
def returns_rows(self):
"""True if this :class:`.ResultProxy` returns rows.
I.e. if it is legal to call the methods
:meth:`~.ResultProxy.fetchone`,
:meth:`~.ResultProxy.fetchmany`
:meth:`~.ResultProxy.fetchall`.
"""
return self._metadata is not None
@property
def is_insert(self):
"""True if this :class:`.ResultProxy` is the result
of a executing an expression language compiled
:func:`.expression.insert` construct.
When True, this implies that the
:attr:`inserted_primary_key` attribute is accessible,
assuming the statement did not include
a user defined "returning" construct.
"""
return self.context.isinsert
def _cursor_description(self):
"""May be overridden by subclasses."""
return self._saved_cursor.description
def close(self, _autoclose_connection=True):
"""Close this ResultProxy.
Closes the underlying DBAPI cursor corresponding to the execution.
Note that any data cached within this ResultProxy is still available.
For some types of results, this may include buffered rows.
If this ResultProxy was generated from an implicit execution,
the underlying Connection will also be closed (returns the
underlying DBAPI connection to the connection pool.)
This method is called automatically when:
* all result rows are exhausted using the fetchXXX() methods.
* cursor.description is None.
"""
if not self.closed:
self.closed = True
self.connection._safe_close_cursor(self.cursor)
if _autoclose_connection and \
self.connection.should_close_with_result:
self.connection.close()
# allow consistent errors
self.cursor = None
def __iter__(self):
while True:
row = self.fetchone()
if row is None:
raise StopIteration
else:
yield row
@util.memoized_property
def inserted_primary_key(self):
"""Return the primary key for the row just inserted.
The return value is a list of scalar values
corresponding to the list of primary key columns
in the target table.
This only applies to single row :func:`.insert`
constructs which did not explicitly specify
:meth:`.Insert.returning`.
Note that primary key columns which specify a
server_default clause,
or otherwise do not qualify as "autoincrement"
columns (see the notes at :class:`.Column`), and were
generated using the database-side default, will
appear in this list as ``None`` unless the backend
supports "returning" and the insert statement executed
with the "implicit returning" enabled.
"""
if not self.context.isinsert:
raise exc.InvalidRequestError(
"Statement is not an insert() expression construct.")
elif self.context._is_explicit_returning:
raise exc.InvalidRequestError(
"Can't call inserted_primary_key when returning() "
"is used.")
return self.context.inserted_primary_key
@util.deprecated("0.6", "Use :attr:`.ResultProxy.inserted_primary_key`")
def last_inserted_ids(self):
"""Return the primary key for the row just inserted."""
return self.inserted_primary_key
def last_updated_params(self):
"""Return the collection of updated parameters from this
execution.
"""
if self.context.executemany:
return self.context.compiled_parameters
else:
return self.context.compiled_parameters[0]
def last_inserted_params(self):
"""Return the collection of inserted parameters from this
execution.
"""
if self.context.executemany:
return self.context.compiled_parameters
else:
return self.context.compiled_parameters[0]
def lastrow_has_defaults(self):
"""Return ``lastrow_has_defaults()`` from the underlying
ExecutionContext.
See ExecutionContext for details.
"""
return self.context.lastrow_has_defaults()
def postfetch_cols(self):
"""Return ``postfetch_cols()`` from the underlying ExecutionContext.
See ExecutionContext for details.
"""
return self.context.postfetch_cols
def prefetch_cols(self):
return self.context.prefetch_cols
def supports_sane_rowcount(self):
"""Return ``supports_sane_rowcount`` from the dialect."""
return self.dialect.supports_sane_rowcount
def supports_sane_multi_rowcount(self):
"""Return ``supports_sane_multi_rowcount`` from the dialect."""
return self.dialect.supports_sane_multi_rowcount
def _fetchone_impl(self):
try:
return self.cursor.fetchone()
except AttributeError:
self._non_result()
def _fetchmany_impl(self, size=None):
try:
if size is None:
return self.cursor.fetchmany()
else:
return self.cursor.fetchmany(size)
except AttributeError:
self._non_result()
def _fetchall_impl(self):
try:
return self.cursor.fetchall()
except AttributeError:
self._non_result()
def _non_result(self):
if self._metadata is None:
raise exc.ResourceClosedError(
"This result object does not return rows. "
"It has been closed automatically.",
)
else:
raise exc.ResourceClosedError("This result object is closed.")
def process_rows(self, rows):
process_row = self._process_row
metadata = self._metadata
keymap = metadata._keymap
processors = metadata._processors
if self._echo:
log = self.context.engine.logger.debug
l = []
for row in rows:
log("Row %r", row)
l.append(process_row(metadata, row, processors, keymap))
return l
else:
return [process_row(metadata, row, processors, keymap)
for row in rows]
def fetchall(self):
"""Fetch all rows, just like DB-API ``cursor.fetchall()``."""
try:
l = self.process_rows(self._fetchall_impl())
self.close()
return l
except Exception, e:
self.connection._handle_dbapi_exception(
e, None, None,
self.cursor, self.context)
raise
def fetchmany(self, size=None):
"""Fetch many rows, just like DB-API
``cursor.fetchmany(size=cursor.arraysize)``.
If rows are present, the cursor remains open after this is called.
Else the cursor is automatically closed and an empty list is returned.
"""
try:
l = self.process_rows(self._fetchmany_impl(size))
if len(l) == 0:
self.close()
return l
except Exception, e:
self.connection._handle_dbapi_exception(
e, None, None,
self.cursor, self.context)
raise
def fetchone(self):
"""Fetch one row, just like DB-API ``cursor.fetchone()``.
If a row is present, the cursor remains open after this is called.
Else the cursor is automatically closed and None is returned.
"""
try:
row = self._fetchone_impl()
if row is not None:
return self.process_rows([row])[0]
else:
self.close()
return None
except Exception, e:
self.connection._handle_dbapi_exception(
e, None, None,
self.cursor, self.context)
raise
def first(self):
"""Fetch the first row and then close the result set unconditionally.
Returns None if no row is present.
"""
if self._metadata is None:
self._non_result()
try:
row = self._fetchone_impl()
except Exception, e:
self.connection._handle_dbapi_exception(
e, None, None,
self.cursor, self.context)
raise
try:
if row is not None:
return self.process_rows([row])[0]
else:
return None
finally:
self.close()
def scalar(self):
"""Fetch the first column of the first row, and close the result set.
Returns None if no row is present.
"""
row = self.first()
if row is not None:
return row[0]
else:
return None
class BufferedRowResultProxy(ResultProxy):
"""A ResultProxy with row buffering behavior.
``ResultProxy`` that buffers the contents of a selection of rows
before ``fetchone()`` is called. This is to allow the results of
``cursor.description`` to be available immediately, when
interfacing with a DB-API that requires rows to be consumed before
this information is available (currently psycopg2, when used with
server-side cursors).
The pre-fetching behavior fetches only one row initially, and then
grows its buffer size by a fixed amount with each successive need
for additional rows up to a size of 100.
"""
def _init_metadata(self):
self.__buffer_rows()
super(BufferedRowResultProxy, self)._init_metadata()
# this is a "growth chart" for the buffering of rows.
# each successive __buffer_rows call will use the next
# value in the list for the buffer size until the max
# is reached
size_growth = {
1 : 5,
5 : 10,
10 : 20,
20 : 50,
50 : 100,
100 : 250,
250 : 500,
500 : 1000
}
def __buffer_rows(self):
size = getattr(self, '_bufsize', 1)
self.__rowbuffer = collections.deque(self.cursor.fetchmany(size))
self._bufsize = self.size_growth.get(size, size)
def _fetchone_impl(self):
if self.closed:
return None
if not self.__rowbuffer:
self.__buffer_rows()
if not self.__rowbuffer:
return None
return self.__rowbuffer.popleft()
def _fetchmany_impl(self, size=None):
if size is None:
return self._fetchall_impl()
result = []
for x in range(0, size):
row = self._fetchone_impl()
if row is None:
break
result.append(row)
return result
def _fetchall_impl(self):
self.__rowbuffer.extend(self.cursor.fetchall())
ret = self.__rowbuffer
self.__rowbuffer = collections.deque()
return ret
class FullyBufferedResultProxy(ResultProxy):
"""A result proxy that buffers rows fully upon creation.
Used for operations where a result is to be delivered
after the database conversation can not be continued,
such as MSSQL INSERT...OUTPUT after an autocommit.
"""
def _init_metadata(self):
super(FullyBufferedResultProxy, self)._init_metadata()
self.__rowbuffer = self._buffer_rows()
def _buffer_rows(self):
return collections.deque(self.cursor.fetchall())
def _fetchone_impl(self):
if self.__rowbuffer:
return self.__rowbuffer.popleft()
else:
return None
def _fetchmany_impl(self, size=None):
if size is None:
return self._fetchall_impl()
result = []
for x in range(0, size):
row = self._fetchone_impl()
if row is None:
break
result.append(row)
return result
def _fetchall_impl(self):
ret = self.__rowbuffer
self.__rowbuffer = collections.deque()
return ret
class BufferedColumnRow(RowProxy):
def __init__(self, parent, row, processors, keymap):
# preprocess row
row = list(row)
# this is a tad faster than using enumerate
index = 0
for processor in parent._orig_processors:
if processor is not None:
row[index] = processor(row[index])
index += 1
row = tuple(row)
super(BufferedColumnRow, self).__init__(parent, row,
processors, keymap)
class BufferedColumnResultProxy(ResultProxy):
"""A ResultProxy with column buffering behavior.
``ResultProxy`` that loads all columns into memory each time
fetchone() is called. If fetchmany() or fetchall() are called,
the full grid of results is fetched. This is to operate with
databases where result rows contain "live" results that fall out
of scope unless explicitly fetched. Currently this includes
cx_Oracle LOB objects.
"""
_process_row = BufferedColumnRow
def _init_metadata(self):
super(BufferedColumnResultProxy, self)._init_metadata()
metadata = self._metadata
# orig_processors will be used to preprocess each row when they are
# constructed.
metadata._orig_processors = metadata._processors
# replace the all type processors by None processors.
metadata._processors = [None for _ in xrange(len(metadata.keys))]
keymap = {}
for k, (func, index) in metadata._keymap.iteritems():
keymap[k] = (None, index)
self._metadata._keymap = keymap
def fetchall(self):
# can't call cursor.fetchall(), since rows must be
# fully processed before requesting more from the DBAPI.
l = []
while True:
row = self.fetchone()
if row is None:
break
l.append(row)
return l
def fetchmany(self, size=None):
# can't call cursor.fetchmany(), since rows must be
# fully processed before requesting more from the DBAPI.
if size is None:
return self.fetchall()
l = []
for i in xrange(size):
row = self.fetchone()
if row is None:
break
l.append(row)
return l
def connection_memoize(key):
"""Decorator, memoize a function in a connection.info stash.
Only applicable to functions which take no arguments other than a
connection. The memo will be stored in ``connection.info[key]``.
"""
@util.decorator
def decorated(fn, self, connection):
connection = connection.connect()
try:
return connection.info[key]
except KeyError:
connection.info[key] = val = fn(self, connection)
return val
return decorated
|