/usr/lib/python2.7/dist-packages/sqlalchemy/orm/strategies.py is in python-sqlalchemy 0.8.4-1build1.
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 | # orm/strategies.py
# Copyright (C) 2005-2013 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
"""sqlalchemy.orm.interfaces.LoaderStrategy
implementations, and related MapperOptions."""
from .. import exc as sa_exc, inspect
from .. import util, log, event
from ..sql import util as sql_util, visitors
from . import (
attributes, interfaces, exc as orm_exc, loading,
unitofwork, util as orm_util
)
from .state import InstanceState
from .util import _none_set
from .interfaces import (
LoaderStrategy, StrategizedOption, MapperOption, PropertyOption,
StrategizedProperty
)
from .session import _state_session
import itertools
def _register_attribute(strategy, mapper, useobject,
compare_function=None,
typecallable=None,
uselist=False,
callable_=None,
proxy_property=None,
active_history=False,
impl_class=None,
**kw
):
prop = strategy.parent_property
attribute_ext = list(util.to_list(prop.extension, default=[]))
listen_hooks = []
if useobject and prop.single_parent:
listen_hooks.append(single_parent_validator)
if prop.key in prop.parent.validators:
fn, include_removes = prop.parent.validators[prop.key]
listen_hooks.append(
lambda desc, prop: orm_util._validator_events(desc,
prop.key, fn, include_removes)
)
if useobject:
listen_hooks.append(unitofwork.track_cascade_events)
# need to assemble backref listeners
# after the singleparentvalidator, mapper validator
backref = kw.pop('backref', None)
if backref:
listen_hooks.append(
lambda desc, prop: attributes.backref_listeners(desc,
backref,
uselist)
)
for m in mapper.self_and_descendants:
if prop is m._props.get(prop.key):
desc = attributes.register_attribute_impl(
m.class_,
prop.key,
parent_token=prop,
uselist=uselist,
compare_function=compare_function,
useobject=useobject,
extension=attribute_ext,
trackparent=useobject and (prop.single_parent
or prop.direction is interfaces.ONETOMANY),
typecallable=typecallable,
callable_=callable_,
active_history=active_history,
impl_class=impl_class,
doc=prop.doc,
**kw
)
for hook in listen_hooks:
hook(desc, prop)
class UninstrumentedColumnLoader(LoaderStrategy):
"""Represent the a non-instrumented MapperProperty.
The polymorphic_on argument of mapper() often results in this,
if the argument is against the with_polymorphic selectable.
"""
def __init__(self, parent):
super(UninstrumentedColumnLoader, self).__init__(parent)
self.columns = self.parent_property.columns
def setup_query(self, context, entity, path, adapter,
column_collection=None, **kwargs):
for c in self.columns:
if adapter:
c = adapter.columns[c]
column_collection.append(c)
def create_row_processor(self, context, path, mapper, row, adapter):
return None, None, None
class ColumnLoader(LoaderStrategy):
"""Provide loading behavior for a :class:`.ColumnProperty`."""
def __init__(self, parent):
super(ColumnLoader, self).__init__(parent)
self.columns = self.parent_property.columns
self.is_composite = hasattr(self.parent_property, 'composite_class')
def setup_query(self, context, entity, path,
adapter, column_collection, **kwargs):
for c in self.columns:
if adapter:
c = adapter.columns[c]
column_collection.append(c)
def init_class_attribute(self, mapper):
self.is_class_level = True
coltype = self.columns[0].type
# TODO: check all columns ? check for foreign key as well?
active_history = self.parent_property.active_history or \
self.columns[0].primary_key
_register_attribute(self, mapper, useobject=False,
compare_function=coltype.compare_values,
active_history=active_history
)
def create_row_processor(self, context, path,
mapper, row, adapter):
key = self.key
# look through list of columns represented here
# to see which, if any, is present in the row.
for col in self.columns:
if adapter:
col = adapter.columns[col]
if col is not None and col in row:
def fetch_col(state, dict_, row):
dict_[key] = row[col]
return fetch_col, None, None
else:
def expire_for_non_present_col(state, dict_, row):
state._expire_attribute_pre_commit(dict_, key)
return expire_for_non_present_col, None, None
log.class_logger(ColumnLoader)
class DeferredColumnLoader(LoaderStrategy):
"""Provide loading behavior for a deferred :class:`.ColumnProperty`."""
def __init__(self, parent):
super(DeferredColumnLoader, self).__init__(parent)
if hasattr(self.parent_property, 'composite_class'):
raise NotImplementedError("Deferred loading for composite "
"types not implemented yet")
self.columns = self.parent_property.columns
self.group = self.parent_property.group
def create_row_processor(self, context, path, mapper, row, adapter):
col = self.columns[0]
if adapter:
col = adapter.columns[col]
key = self.key
if col in row:
return self.parent_property._get_strategy(ColumnLoader).\
create_row_processor(
context, path, mapper, row, adapter)
elif not self.is_class_level:
set_deferred_for_local_state = InstanceState._row_processor(
mapper.class_manager,
LoadDeferredColumns(key), key)
return set_deferred_for_local_state, None, None
else:
def reset_col_for_deferred(state, dict_, row):
# reset state on the key so that deferred callables
# fire off on next access.
state._reset(dict_, key)
return reset_col_for_deferred, None, None
def init_class_attribute(self, mapper):
self.is_class_level = True
_register_attribute(self, mapper, useobject=False,
compare_function=self.columns[0].type.compare_values,
callable_=self._load_for_state,
expire_missing=False
)
def setup_query(self, context, entity, path, adapter,
only_load_props=None, **kwargs):
if (
self.group is not None and
context.attributes.get(('undefer', self.group), False)
) or (only_load_props and self.key in only_load_props):
self.parent_property._get_strategy(ColumnLoader).\
setup_query(context, entity,
path, adapter, **kwargs)
def _load_for_state(self, state, passive):
if not state.key:
return attributes.ATTR_EMPTY
if not passive & attributes.SQL_OK:
return attributes.PASSIVE_NO_RESULT
localparent = state.manager.mapper
if self.group:
toload = [
p.key for p in
localparent.iterate_properties
if isinstance(p, StrategizedProperty) and
isinstance(p.strategy, DeferredColumnLoader) and
p.group == self.group
]
else:
toload = [self.key]
# narrow the keys down to just those which have no history
group = [k for k in toload if k in state.unmodified]
session = _state_session(state)
if session is None:
raise orm_exc.DetachedInstanceError(
"Parent instance %s is not bound to a Session; "
"deferred load operation of attribute '%s' cannot proceed" %
(orm_util.state_str(state), self.key)
)
query = session.query(localparent)
if loading.load_on_ident(query, state.key,
only_load_props=group, refresh_state=state) is None:
raise orm_exc.ObjectDeletedError(state)
return attributes.ATTR_WAS_SET
log.class_logger(DeferredColumnLoader)
class LoadDeferredColumns(object):
"""serializable loader object used by DeferredColumnLoader"""
def __init__(self, key):
self.key = key
def __call__(self, state, passive=attributes.PASSIVE_OFF):
key = self.key
localparent = state.manager.mapper
prop = localparent._props[key]
strategy = prop._strategies[DeferredColumnLoader]
return strategy._load_for_state(state, passive)
class DeferredOption(StrategizedOption):
propagate_to_loaders = True
def __init__(self, key, defer=False):
super(DeferredOption, self).__init__(key)
self.defer = defer
def get_strategy_class(self):
if self.defer:
return DeferredColumnLoader
else:
return ColumnLoader
class UndeferGroupOption(MapperOption):
propagate_to_loaders = True
def __init__(self, group):
self.group = group
def process_query(self, query):
query._attributes[("undefer", self.group)] = True
class AbstractRelationshipLoader(LoaderStrategy):
"""LoaderStratgies which deal with related objects."""
def __init__(self, parent):
super(AbstractRelationshipLoader, self).__init__(parent)
self.mapper = self.parent_property.mapper
self.target = self.parent_property.target
self.uselist = self.parent_property.uselist
class NoLoader(AbstractRelationshipLoader):
"""Provide loading behavior for a :class:`.RelationshipProperty`
with "lazy=None".
"""
def init_class_attribute(self, mapper):
self.is_class_level = True
_register_attribute(self, mapper,
useobject=True,
uselist=self.parent_property.uselist,
typecallable=self.parent_property.collection_class,
)
def create_row_processor(self, context, path, mapper, row, adapter):
def invoke_no_load(state, dict_, row):
state._initialize(self.key)
return invoke_no_load, None, None
log.class_logger(NoLoader)
class LazyLoader(AbstractRelationshipLoader):
"""Provide loading behavior for a :class:`.RelationshipProperty`
with "lazy=True", that is loads when first accessed.
"""
def __init__(self, parent):
super(LazyLoader, self).__init__(parent)
join_condition = self.parent_property._join_condition
self._lazywhere, \
self._bind_to_col, \
self._equated_columns = join_condition.create_lazy_clause()
self._rev_lazywhere, \
self._rev_bind_to_col, \
self._rev_equated_columns = join_condition.create_lazy_clause(
reverse_direction=True)
self.logger.info("%s lazy loading clause %s", self, self._lazywhere)
# determine if our "lazywhere" clause is the same as the mapper's
# get() clause. then we can just use mapper.get()
#from sqlalchemy.orm import query
self.use_get = not self.uselist and \
self.mapper._get_clause[0].compare(
self._lazywhere,
use_proxies=True,
equivalents=self.mapper._equivalent_columns
)
if self.use_get:
for col in self._equated_columns.keys():
if col in self.mapper._equivalent_columns:
for c in self.mapper._equivalent_columns[col]:
self._equated_columns[c] = self._equated_columns[col]
self.logger.info("%s will use query.get() to "
"optimize instance loads" % self)
def init_class_attribute(self, mapper):
self.is_class_level = True
active_history = (
self.parent_property.active_history or
self.parent_property.direction is not interfaces.MANYTOONE or
not self.use_get
)
# MANYTOONE currently only needs the
# "old" value for delete-orphan
# cascades. the required _SingleParentValidator
# will enable active_history
# in that case. otherwise we don't need the
# "old" value during backref operations.
_register_attribute(self,
mapper,
useobject=True,
callable_=self._load_for_state,
uselist=self.parent_property.uselist,
backref=self.parent_property.back_populates,
typecallable=self.parent_property.collection_class,
active_history=active_history
)
def lazy_clause(self, state, reverse_direction=False,
alias_secondary=False,
adapt_source=None,
passive=None):
if state is None:
return self._lazy_none_clause(
reverse_direction,
adapt_source=adapt_source)
if not reverse_direction:
criterion, bind_to_col, rev = \
self._lazywhere, \
self._bind_to_col, \
self._equated_columns
else:
criterion, bind_to_col, rev = \
self._rev_lazywhere, \
self._rev_bind_to_col, \
self._rev_equated_columns
if reverse_direction:
mapper = self.parent_property.mapper
else:
mapper = self.parent_property.parent
o = state.obj() # strong ref
dict_ = attributes.instance_dict(o)
# use the "committed state" only if we're in a flush
# for this state.
if passive and passive & attributes.LOAD_AGAINST_COMMITTED:
def visit_bindparam(bindparam):
if bindparam._identifying_key in bind_to_col:
bindparam.callable = \
lambda: mapper._get_committed_state_attr_by_column(
state, dict_,
bind_to_col[bindparam._identifying_key])
else:
def visit_bindparam(bindparam):
if bindparam._identifying_key in bind_to_col:
bindparam.callable = \
lambda: mapper._get_state_attr_by_column(
state, dict_,
bind_to_col[bindparam._identifying_key])
if self.parent_property.secondary is not None and alias_secondary:
criterion = sql_util.ClauseAdapter(
self.parent_property.secondary.alias()).\
traverse(criterion)
criterion = visitors.cloned_traverse(
criterion, {}, {'bindparam': visit_bindparam})
if adapt_source:
criterion = adapt_source(criterion)
return criterion
def _lazy_none_clause(self, reverse_direction=False, adapt_source=None):
if not reverse_direction:
criterion, bind_to_col, rev = \
self._lazywhere, \
self._bind_to_col,\
self._equated_columns
else:
criterion, bind_to_col, rev = \
self._rev_lazywhere, \
self._rev_bind_to_col, \
self._rev_equated_columns
criterion = sql_util.adapt_criterion_to_null(criterion, bind_to_col)
if adapt_source:
criterion = adapt_source(criterion)
return criterion
def _load_for_state(self, state, passive):
if not state.key and \
(
(
not self.parent_property.load_on_pending
and not state._load_pending
)
or not state.session_id
):
return attributes.ATTR_EMPTY
pending = not state.key
ident_key = None
if (
(not passive & attributes.SQL_OK and not self.use_get)
or
(not passive & attributes.NON_PERSISTENT_OK and pending)
):
return attributes.PASSIVE_NO_RESULT
session = _state_session(state)
if not session:
raise orm_exc.DetachedInstanceError(
"Parent instance %s is not bound to a Session; "
"lazy load operation of attribute '%s' cannot proceed" %
(orm_util.state_str(state), self.key)
)
# if we have a simple primary key load, check the
# identity map without generating a Query at all
if self.use_get:
ident = self._get_ident_for_use_get(
session,
state,
passive
)
if attributes.PASSIVE_NO_RESULT in ident:
return attributes.PASSIVE_NO_RESULT
elif attributes.NEVER_SET in ident:
return attributes.NEVER_SET
if _none_set.issuperset(ident):
return None
ident_key = self.mapper.identity_key_from_primary_key(ident)
instance = loading.get_from_identity(session, ident_key, passive)
if instance is not None:
return instance
elif not passive & attributes.SQL_OK or \
not passive & attributes.RELATED_OBJECT_OK:
return attributes.PASSIVE_NO_RESULT
return self._emit_lazyload(session, state, ident_key, passive)
def _get_ident_for_use_get(self, session, state, passive):
instance_mapper = state.manager.mapper
if passive & attributes.LOAD_AGAINST_COMMITTED:
get_attr = instance_mapper._get_committed_state_attr_by_column
else:
get_attr = instance_mapper._get_state_attr_by_column
dict_ = state.dict
return [
get_attr(
state,
dict_,
self._equated_columns[pk],
passive=passive)
for pk in self.mapper.primary_key
]
def _emit_lazyload(self, session, state, ident_key, passive):
q = session.query(self.mapper)._adapt_all_clauses()
q = q._with_invoke_all_eagers(False)
pending = not state.key
# don't autoflush on pending
if pending:
q = q.autoflush(False)
if state.load_path:
q = q._with_current_path(state.load_path[self.parent_property])
if state.load_options:
q = q._conditional_options(*state.load_options)
if self.use_get:
return loading.load_on_ident(q, ident_key)
if self.parent_property.order_by:
q = q.order_by(*util.to_list(self.parent_property.order_by))
for rev in self.parent_property._reverse_property:
# reverse props that are MANYTOONE are loading *this*
# object from get(), so don't need to eager out to those.
if rev.direction is interfaces.MANYTOONE and \
rev._use_get and \
not isinstance(rev.strategy, LazyLoader):
q = q.options(EagerLazyOption((rev.key,), lazy='select'))
lazy_clause = self.lazy_clause(state, passive=passive)
if pending:
bind_values = sql_util.bind_values(lazy_clause)
if None in bind_values:
return None
q = q.filter(lazy_clause)
result = q.all()
if self.uselist:
return result
else:
l = len(result)
if l:
if l > 1:
util.warn(
"Multiple rows returned with "
"uselist=False for lazily-loaded attribute '%s' "
% self.parent_property)
return result[0]
else:
return None
def create_row_processor(self, context, path,
mapper, row, adapter):
key = self.key
if not self.is_class_level:
# we are not the primary manager for this attribute
# on this class - set up a
# per-instance lazyloader, which will override the
# class-level behavior.
# this currently only happens when using a
# "lazyload" option on a "no load"
# attribute - "eager" attributes always have a
# class-level lazyloader installed.
set_lazy_callable = InstanceState._row_processor(
mapper.class_manager,
LoadLazyAttribute(key), key)
return set_lazy_callable, None, None
else:
def reset_for_lazy_callable(state, dict_, row):
# we are the primary manager for this attribute on
# this class - reset its
# per-instance attribute state, so that the class-level
# lazy loader is
# executed when next referenced on this instance.
# this is needed in
# populate_existing() types of scenarios to reset
# any existing state.
state._reset(dict_, key)
return reset_for_lazy_callable, None, None
log.class_logger(LazyLoader)
class LoadLazyAttribute(object):
"""serializable loader object used by LazyLoader"""
def __init__(self, key):
self.key = key
def __call__(self, state, passive=attributes.PASSIVE_OFF):
key = self.key
instance_mapper = state.manager.mapper
prop = instance_mapper._props[key]
strategy = prop._strategies[LazyLoader]
return strategy._load_for_state(state, passive)
class ImmediateLoader(AbstractRelationshipLoader):
def init_class_attribute(self, mapper):
self.parent_property.\
_get_strategy(LazyLoader).\
init_class_attribute(mapper)
def setup_query(self, context, entity,
path, adapter, column_collection=None,
parentmapper=None, **kwargs):
pass
def create_row_processor(self, context, path,
mapper, row, adapter):
def load_immediate(state, dict_, row):
state.get_impl(self.key).get(state, dict_)
return None, None, load_immediate
class SubqueryLoader(AbstractRelationshipLoader):
def __init__(self, parent):
super(SubqueryLoader, self).__init__(parent)
self.join_depth = self.parent_property.join_depth
def init_class_attribute(self, mapper):
self.parent_property.\
_get_strategy(LazyLoader).\
init_class_attribute(mapper)
def setup_query(self, context, entity,
path, adapter,
column_collection=None,
parentmapper=None, **kwargs):
if not context.query._enable_eagerloads:
return
path = path[self.parent_property]
# build up a path indicating the path from the leftmost
# entity to the thing we're subquery loading.
with_poly_info = path.get(context, "path_with_polymorphic", None)
if with_poly_info is not None:
effective_entity = with_poly_info.entity
else:
effective_entity = self.mapper
subq_path = context.attributes.get(('subquery_path', None),
orm_util.PathRegistry.root)
subq_path = subq_path + path
# if not via query option, check for
# a cycle
if not path.contains(context, "loaderstrategy"):
if self.join_depth:
if path.length / 2 > self.join_depth:
return
elif subq_path.contains_mapper(self.mapper):
return
subq_mapper, leftmost_mapper, leftmost_attr, leftmost_relationship = \
self._get_leftmost(subq_path)
orig_query = context.attributes.get(
("orig_query", SubqueryLoader),
context.query)
# generate a new Query from the original, then
# produce a subquery from it.
left_alias = self._generate_from_original_query(
orig_query, leftmost_mapper,
leftmost_attr, leftmost_relationship,
entity.mapper
)
# generate another Query that will join the
# left alias to the target relationships.
# basically doing a longhand
# "from_self()". (from_self() itself not quite industrial
# strength enough for all contingencies...but very close)
q = orig_query.session.query(effective_entity)
q._attributes = {
("orig_query", SubqueryLoader): orig_query,
('subquery_path', None): subq_path
}
q = q._enable_single_crit(False)
to_join, local_attr, parent_alias = \
self._prep_for_joins(left_alias, subq_path)
q = q.order_by(*local_attr)
q = q.add_columns(*local_attr)
q = self._apply_joins(q, to_join, left_alias,
parent_alias, effective_entity)
q = self._setup_options(q, subq_path, orig_query, effective_entity)
q = self._setup_outermost_orderby(q)
# add new query to attributes to be picked up
# by create_row_processor
path.set(context, "subquery", q)
def _get_leftmost(self, subq_path):
subq_path = subq_path.path
subq_mapper = orm_util._class_to_mapper(subq_path[0])
# determine attributes of the leftmost mapper
if self.parent.isa(subq_mapper) and self.parent_property is subq_path[1]:
leftmost_mapper, leftmost_prop = \
self.parent, self.parent_property
else:
leftmost_mapper, leftmost_prop = \
subq_mapper, \
subq_path[1]
leftmost_cols = leftmost_prop.local_columns
leftmost_attr = [
leftmost_mapper._columntoproperty[c].class_attribute
for c in leftmost_cols
]
return subq_mapper, leftmost_mapper, leftmost_attr, leftmost_prop
def _generate_from_original_query(self,
orig_query, leftmost_mapper,
leftmost_attr, leftmost_relationship,
entity_mapper
):
# reformat the original query
# to look only for significant columns
q = orig_query._clone().correlate(None)
# set a real "from" if not present, as this is more
# accurate than just going off of the column expression
if not q._from_obj and entity_mapper.isa(leftmost_mapper):
q._set_select_from([entity_mapper], False)
target_cols = q._adapt_col_list(leftmost_attr)
# select from the identity columns of the outer
q._set_entities(target_cols)
distinct_target_key = leftmost_relationship.distinct_target_key
if distinct_target_key is True:
q._distinct = True
elif distinct_target_key is None:
# if target_cols refer to a non-primary key or only
# part of a composite primary key, set the q as distinct
for t in set(c.table for c in target_cols):
if not set(target_cols).issuperset(t.primary_key):
q._distinct = True
break
if q._order_by is False:
q._order_by = leftmost_mapper.order_by
# don't need ORDER BY if no limit/offset
if q._limit is None and q._offset is None:
q._order_by = None
# the original query now becomes a subquery
# which we'll join onto.
embed_q = q.with_labels().subquery()
left_alias = orm_util.AliasedClass(leftmost_mapper, embed_q,
use_mapper_path=True)
return left_alias
def _prep_for_joins(self, left_alias, subq_path):
# figure out what's being joined. a.k.a. the fun part
to_join = []
pairs = list(subq_path.pairs())
for i, (mapper, prop) in enumerate(pairs):
if i > 0:
# look at the previous mapper in the chain -
# if it is as or more specific than this prop's
# mapper, use that instead.
# note we have an assumption here that
# the non-first element is always going to be a mapper,
# not an AliasedClass
prev_mapper = pairs[i - 1][1].mapper
to_append = prev_mapper if prev_mapper.isa(mapper) else mapper
else:
to_append = mapper
to_join.append((to_append, prop.key))
# determine the immediate parent class we are joining from,
# which needs to be aliased.
if len(to_join) > 1:
info = inspect(to_join[-1][0])
if len(to_join) < 2:
# in the case of a one level eager load, this is the
# leftmost "left_alias".
parent_alias = left_alias
elif info.mapper.isa(self.parent):
# In the case of multiple levels, retrieve
# it from subq_path[-2]. This is the same as self.parent
# in the vast majority of cases, and [ticket:2014]
# illustrates a case where sub_path[-2] is a subclass
# of self.parent
parent_alias = orm_util.AliasedClass(to_join[-1][0],
use_mapper_path=True)
else:
# if of_type() were used leading to this relationship,
# self.parent is more specific than subq_path[-2]
parent_alias = orm_util.AliasedClass(self.parent,
use_mapper_path=True)
local_cols = self.parent_property.local_columns
local_attr = [
getattr(parent_alias, self.parent._columntoproperty[c].key)
for c in local_cols
]
return to_join, local_attr, parent_alias
def _apply_joins(self, q, to_join, left_alias, parent_alias,
effective_entity):
for i, (mapper, key) in enumerate(to_join):
# we need to use query.join() as opposed to
# orm.join() here because of the
# rich behavior it brings when dealing with
# "with_polymorphic" mappers. "aliased"
# and "from_joinpoint" take care of most of
# the chaining and aliasing for us.
first = i == 0
middle = i < len(to_join) - 1
second_to_last = i == len(to_join) - 2
last = i == len(to_join) - 1
if first:
attr = getattr(left_alias, key)
if last and effective_entity is not self.mapper:
attr = attr.of_type(effective_entity)
else:
if last and effective_entity is not self.mapper:
attr = getattr(parent_alias, key).\
of_type(effective_entity)
else:
attr = key
if second_to_last:
q = q.join(parent_alias, attr, from_joinpoint=True)
else:
q = q.join(attr, aliased=middle, from_joinpoint=True)
return q
def _setup_options(self, q, subq_path, orig_query, effective_entity):
# propagate loader options etc. to the new query.
# these will fire relative to subq_path.
q = q._with_current_path(subq_path)
q = q._conditional_options(*orig_query._with_options)
if orig_query._populate_existing:
q._populate_existing = orig_query._populate_existing
return q
def _setup_outermost_orderby(self, q):
if self.parent_property.order_by:
# if there's an ORDER BY, alias it the same
# way joinedloader does, but we have to pull out
# the "eagerjoin" from the query.
# this really only picks up the "secondary" table
# right now.
eagerjoin = q._from_obj[0]
eager_order_by = \
eagerjoin._target_adapter.\
copy_and_process(
util.to_list(
self.parent_property.order_by
)
)
q = q.order_by(*eager_order_by)
return q
def create_row_processor(self, context, path,
mapper, row, adapter):
if not self.parent.class_manager[self.key].impl.supports_population:
raise sa_exc.InvalidRequestError(
"'%s' does not support object "
"population - eager loading cannot be applied." %
self)
path = path[self.parent_property]
subq = path.get(context, 'subquery')
if subq is None:
return None, None, None
local_cols = self.parent_property.local_columns
# cache the loaded collections in the context
# so that inheriting mappers don't re-load when they
# call upon create_row_processor again
collections = path.get(context, "collections")
if collections is None:
collections = dict(
(k, [v[0] for v in v])
for k, v in itertools.groupby(
subq,
lambda x: x[1:]
))
path.set(context, 'collections', collections)
if adapter:
local_cols = [adapter.columns[c] for c in local_cols]
if self.uselist:
return self._create_collection_loader(collections, local_cols)
else:
return self._create_scalar_loader(collections, local_cols)
def _create_collection_loader(self, collections, local_cols):
def load_collection_from_subq(state, dict_, row):
collection = collections.get(
tuple([row[col] for col in local_cols]),
()
)
state.get_impl(self.key).\
set_committed_value(state, dict_, collection)
return load_collection_from_subq, None, None
def _create_scalar_loader(self, collections, local_cols):
def load_scalar_from_subq(state, dict_, row):
collection = collections.get(
tuple([row[col] for col in local_cols]),
(None,)
)
if len(collection) > 1:
util.warn(
"Multiple rows returned with "
"uselist=False for eagerly-loaded attribute '%s' "
% self)
scalar = collection[0]
state.get_impl(self.key).\
set_committed_value(state, dict_, scalar)
return load_scalar_from_subq, None, None
log.class_logger(SubqueryLoader)
class JoinedLoader(AbstractRelationshipLoader):
"""Provide loading behavior for a :class:`.RelationshipProperty`
using joined eager loading.
"""
def __init__(self, parent):
super(JoinedLoader, self).__init__(parent)
self.join_depth = self.parent_property.join_depth
def init_class_attribute(self, mapper):
self.parent_property.\
_get_strategy(LazyLoader).init_class_attribute(mapper)
def setup_query(self, context, entity, path, adapter, \
column_collection=None, parentmapper=None,
allow_innerjoin=True,
**kwargs):
"""Add a left outer join to the statement thats being constructed."""
if not context.query._enable_eagerloads:
return
path = path[self.parent_property]
with_polymorphic = None
user_defined_adapter = path.get(context,
"user_defined_eager_row_processor",
False)
if user_defined_adapter is not False:
clauses, adapter, add_to_collection = \
self._get_user_defined_adapter(
context, entity, path, adapter,
user_defined_adapter
)
else:
# if not via query option, check for
# a cycle
if not path.contains(context, "loaderstrategy"):
if self.join_depth:
if path.length / 2 > self.join_depth:
return
elif path.contains_mapper(self.mapper):
return
clauses, adapter, add_to_collection, \
allow_innerjoin = self._generate_row_adapter(
context, entity, path, adapter,
column_collection, parentmapper, allow_innerjoin
)
with_poly_info = path.get(
context,
"path_with_polymorphic",
None
)
if with_poly_info is not None:
with_polymorphic = with_poly_info.with_polymorphic_mappers
else:
with_polymorphic = None
path = path[self.mapper]
for value in self.mapper._iterate_polymorphic_properties(
mappers=with_polymorphic):
value.setup(
context,
entity,
path,
clauses,
parentmapper=self.mapper,
column_collection=add_to_collection,
allow_innerjoin=allow_innerjoin)
def _get_user_defined_adapter(self, context, entity,
path, adapter, user_defined_adapter):
adapter = entity._get_entity_clauses(context.query, context)
if adapter and user_defined_adapter:
user_defined_adapter = user_defined_adapter.wrap(adapter)
path.set(context, "user_defined_eager_row_processor",
user_defined_adapter)
elif adapter:
user_defined_adapter = adapter
path.set(context, "user_defined_eager_row_processor",
user_defined_adapter)
add_to_collection = context.primary_columns
return user_defined_adapter, adapter, add_to_collection
def _generate_row_adapter(self,
context, entity, path, adapter,
column_collection, parentmapper, allow_innerjoin
):
with_poly_info = path.get(
context,
"path_with_polymorphic",
None
)
if with_poly_info:
to_adapt = with_poly_info.entity
else:
to_adapt = orm_util.AliasedClass(self.mapper,
use_mapper_path=True)
clauses = orm_util.ORMAdapter(
to_adapt,
equivalents=self.mapper._equivalent_columns,
adapt_required=True)
assert clauses.aliased_class is not None
if self.parent_property.direction != interfaces.MANYTOONE:
context.multi_row_eager_loaders = True
innerjoin = allow_innerjoin and path.get(context,
"eager_join_type",
self.parent_property.innerjoin)
if not innerjoin:
# if this is an outer join, all eager joins from
# here must also be outer joins
allow_innerjoin = False
context.create_eager_joins.append(
(self._create_eager_join, context,
entity, path, adapter,
parentmapper, clauses, innerjoin)
)
add_to_collection = context.secondary_columns
path.set(context, "eager_row_processor", clauses)
return clauses, adapter, add_to_collection, allow_innerjoin
def _create_eager_join(self, context, entity,
path, adapter, parentmapper,
clauses, innerjoin):
if parentmapper is None:
localparent = entity.mapper
else:
localparent = parentmapper
# whether or not the Query will wrap the selectable in a subquery,
# and then attach eager load joins to that (i.e., in the case of
# LIMIT/OFFSET etc.)
should_nest_selectable = context.multi_row_eager_loaders and \
context.query._should_nest_selectable
entity_key = None
if entity not in context.eager_joins and \
not should_nest_selectable and \
context.from_clause:
index, clause = \
sql_util.find_join_source(
context.from_clause, entity.selectable)
if clause is not None:
# join to an existing FROM clause on the query.
# key it to its list index in the eager_joins dict.
# Query._compile_context will adapt as needed and
# append to the FROM clause of the select().
entity_key, default_towrap = index, clause
if entity_key is None:
entity_key, default_towrap = entity, entity.selectable
towrap = context.eager_joins.setdefault(entity_key, default_towrap)
if adapter:
if getattr(adapter, 'aliased_class', None):
onclause = getattr(
adapter.aliased_class, self.key,
self.parent_property)
else:
onclause = getattr(
orm_util.AliasedClass(
self.parent,
adapter.selectable,
use_mapper_path=True
),
self.key, self.parent_property
)
else:
onclause = self.parent_property
assert clauses.aliased_class is not None
context.eager_joins[entity_key] = eagerjoin = \
orm_util.join(
towrap,
clauses.aliased_class,
onclause,
isouter=not innerjoin
)
# send a hint to the Query as to where it may "splice" this join
eagerjoin.stop_on = entity.selectable
if self.parent_property.secondary is None and \
not parentmapper:
# for parentclause that is the non-eager end of the join,
# ensure all the parent cols in the primaryjoin are actually
# in the
# columns clause (i.e. are not deferred), so that aliasing applied
# by the Query propagates those columns outward.
# This has the effect
# of "undefering" those columns.
for col in sql_util.find_columns(
self.parent_property.primaryjoin):
if localparent.mapped_table.c.contains_column(col):
if adapter:
col = adapter.columns[col]
context.primary_columns.append(col)
if self.parent_property.order_by:
context.eager_order_by += \
eagerjoin._target_adapter.\
copy_and_process(
util.to_list(
self.parent_property.order_by
)
)
def _create_eager_adapter(self, context, row, adapter, path):
user_defined_adapter = path.get(context,
"user_defined_eager_row_processor",
False)
if user_defined_adapter is not False:
decorator = user_defined_adapter
# user defined eagerloads are part of the "primary"
# portion of the load.
# the adapters applied to the Query should be honored.
if context.adapter and decorator:
decorator = decorator.wrap(context.adapter)
elif context.adapter:
decorator = context.adapter
else:
decorator = path.get(context, "eager_row_processor")
if decorator is None:
return False
try:
self.mapper.identity_key_from_row(row, decorator)
return decorator
except KeyError:
# no identity key - dont return a row
# processor, will cause a degrade to lazy
return False
def create_row_processor(self, context, path, mapper, row, adapter):
if not self.parent.class_manager[self.key].impl.supports_population:
raise sa_exc.InvalidRequestError(
"'%s' does not support object "
"population - eager loading cannot be applied." %
self)
our_path = path[self.parent_property]
eager_adapter = self._create_eager_adapter(
context,
row,
adapter, our_path)
if eager_adapter is not False:
key = self.key
_instance = loading.instance_processor(
self.mapper,
context,
our_path[self.mapper],
eager_adapter)
if not self.uselist:
return self._create_scalar_loader(context, key, _instance)
else:
return self._create_collection_loader(context, key, _instance)
else:
return self.parent_property.\
_get_strategy(LazyLoader).\
create_row_processor(
context, path,
mapper, row, adapter)
def _create_collection_loader(self, context, key, _instance):
def load_collection_from_joined_new_row(state, dict_, row):
collection = attributes.init_state_collection(
state, dict_, key)
result_list = util.UniqueAppender(collection,
'append_without_event')
context.attributes[(state, key)] = result_list
_instance(row, result_list)
def load_collection_from_joined_existing_row(state, dict_, row):
if (state, key) in context.attributes:
result_list = context.attributes[(state, key)]
else:
# appender_key can be absent from context.attributes
# with isnew=False when self-referential eager loading
# is used; the same instance may be present in two
# distinct sets of result columns
collection = attributes.init_state_collection(state,
dict_, key)
result_list = util.UniqueAppender(
collection,
'append_without_event')
context.attributes[(state, key)] = result_list
_instance(row, result_list)
def load_collection_from_joined_exec(state, dict_, row):
_instance(row, None)
return load_collection_from_joined_new_row, \
load_collection_from_joined_existing_row, \
None, load_collection_from_joined_exec
def _create_scalar_loader(self, context, key, _instance):
def load_scalar_from_joined_new_row(state, dict_, row):
# set a scalar object instance directly on the parent
# object, bypassing InstrumentedAttribute event handlers.
dict_[key] = _instance(row, None)
def load_scalar_from_joined_existing_row(state, dict_, row):
# call _instance on the row, even though the object has
# been created, so that we further descend into properties
existing = _instance(row, None)
if existing is not None \
and key in dict_ \
and existing is not dict_[key]:
util.warn(
"Multiple rows returned with "
"uselist=False for eagerly-loaded attribute '%s' "
% self)
def load_scalar_from_joined_exec(state, dict_, row):
_instance(row, None)
return load_scalar_from_joined_new_row, \
load_scalar_from_joined_existing_row, \
None, load_scalar_from_joined_exec
log.class_logger(JoinedLoader)
class EagerLazyOption(StrategizedOption):
def __init__(self, key, lazy=True, chained=False,
propagate_to_loaders=True
):
if isinstance(key[0], basestring) and key[0] == '*':
if len(key) != 1:
raise sa_exc.ArgumentError(
"Wildcard identifier '*' must "
"be specified alone.")
key = ("relationship:*",)
propagate_to_loaders = False
super(EagerLazyOption, self).__init__(key)
self.lazy = lazy
self.chained = chained
self.propagate_to_loaders = propagate_to_loaders
self.strategy_cls = factory(lazy)
def get_strategy_class(self):
return self.strategy_cls
_factory = {
False: JoinedLoader,
"joined": JoinedLoader,
None: NoLoader,
"noload": NoLoader,
"select": LazyLoader,
True: LazyLoader,
"subquery": SubqueryLoader,
"immediate": ImmediateLoader
}
def factory(identifier):
return _factory.get(identifier, LazyLoader)
class EagerJoinOption(PropertyOption):
def __init__(self, key, innerjoin, chained=False):
super(EagerJoinOption, self).__init__(key)
self.innerjoin = innerjoin
self.chained = chained
def process_query_property(self, query, paths):
if self.chained:
for path in paths:
path.set(query, "eager_join_type", self.innerjoin)
else:
paths[-1].set(query, "eager_join_type", self.innerjoin)
class LoadEagerFromAliasOption(PropertyOption):
def __init__(self, key, alias=None, chained=False):
super(LoadEagerFromAliasOption, self).__init__(key)
if alias is not None:
if not isinstance(alias, basestring):
info = inspect(alias)
alias = info.selectable
self.alias = alias
self.chained = chained
def process_query_property(self, query, paths):
if self.chained:
for path in paths[0:-1]:
(root_mapper, prop) = path.path[-2:]
adapter = query._polymorphic_adapters.get(prop.mapper, None)
path.setdefault(query,
"user_defined_eager_row_processor",
adapter)
root_mapper, prop = paths[-1].path[-2:]
if self.alias is not None:
if isinstance(self.alias, basestring):
self.alias = prop.target.alias(self.alias)
paths[-1].set(query, "user_defined_eager_row_processor",
sql_util.ColumnAdapter(self.alias,
equivalents=prop.mapper._equivalent_columns)
)
else:
if paths[-1].contains(query, "path_with_polymorphic"):
with_poly_info = paths[-1].get(query, "path_with_polymorphic")
adapter = orm_util.ORMAdapter(
with_poly_info.entity,
equivalents=prop.mapper._equivalent_columns,
adapt_required=True)
else:
adapter = query._polymorphic_adapters.get(prop.mapper, None)
paths[-1].set(query, "user_defined_eager_row_processor",
adapter)
def single_parent_validator(desc, prop):
def _do_check(state, value, oldvalue, initiator):
if value is not None and initiator.key == prop.key:
hasparent = initiator.hasparent(attributes.instance_state(value))
if hasparent and oldvalue is not value:
raise sa_exc.InvalidRequestError(
"Instance %s is already associated with an instance "
"of %s via its %s attribute, and is only allowed a "
"single parent." %
(orm_util.instance_str(value), state.class_, prop)
)
return value
def append(state, value, initiator):
return _do_check(state, value, None, initiator)
def set_(state, value, oldvalue, initiator):
return _do_check(state, value, oldvalue, initiator)
event.listen(desc, 'append', append, raw=True, retval=True,
active_history=True)
event.listen(desc, 'set', set_, raw=True, retval=True,
active_history=True)
|