/usr/share/pyshared/sqlalchemy/orm/interfaces.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 | # orm/interfaces.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
"""
Contains various base classes used throughout the ORM.
Defines the now deprecated ORM extension classes as well
as ORM internals.
Other than the deprecated extensions, this module and the
classes within should be considered mostly private.
"""
from itertools import chain
from sqlalchemy import exc as sa_exc
from sqlalchemy import util
from sqlalchemy.sql import operators
deque = __import__('collections').deque
mapperutil = util.importlater('sqlalchemy.orm', 'util')
collections = None
__all__ = (
'AttributeExtension',
'EXT_CONTINUE',
'EXT_STOP',
'ExtensionOption',
'InstrumentationManager',
'LoaderStrategy',
'MapperExtension',
'MapperOption',
'MapperProperty',
'PropComparator',
'PropertyOption',
'SessionExtension',
'StrategizedOption',
'StrategizedProperty',
'build_path',
)
EXT_CONTINUE = util.symbol('EXT_CONTINUE')
EXT_STOP = util.symbol('EXT_STOP')
ONETOMANY = util.symbol('ONETOMANY')
MANYTOONE = util.symbol('MANYTOONE')
MANYTOMANY = util.symbol('MANYTOMANY')
from deprecated_interfaces import AttributeExtension, SessionExtension, \
MapperExtension
class MapperProperty(object):
"""Manage the relationship of a ``Mapper`` to a single class
attribute, as well as that attribute as it appears on individual
instances of the class, including attribute instrumentation,
attribute access, loading behavior, and dependency calculations.
The most common occurrences of :class:`.MapperProperty` are the
mapped :class:`.Column`, which is represented in a mapping as
an instance of :class:`.ColumnProperty`,
and a reference to another class produced by :func:`.relationship`,
represented in the mapping as an instance of :class:`.RelationshipProperty`.
"""
cascade = ()
"""The set of 'cascade' attribute names.
This collection is checked before the 'cascade_iterator' method is called.
"""
def setup(self, context, entity, path, reduced_path, adapter, **kwargs):
"""Called by Query for the purposes of constructing a SQL statement.
Each MapperProperty associated with the target mapper processes the
statement referenced by the query context, adding columns and/or
criterion as appropriate.
"""
pass
def create_row_processor(self, context, path, reduced_path,
mapper, row, adapter):
"""Return a 3-tuple consisting of three row processing functions.
"""
return None, None, None
def cascade_iterator(self, type_, state, visited_instances=None,
halt_on=None):
"""Iterate through instances related to the given instance for
a particular 'cascade', starting with this MapperProperty.
Return an iterator3-tuples (instance, mapper, state).
Note that the 'cascade' collection on this MapperProperty is
checked first for the given type before cascade_iterator is called.
See PropertyLoader for the related instance implementation.
"""
return iter(())
def set_parent(self, parent, init):
self.parent = parent
def instrument_class(self, mapper):
raise NotImplementedError()
_compile_started = False
_compile_finished = False
def init(self):
"""Called after all mappers are created to assemble
relationships between mappers and perform other post-mapper-creation
initialization steps.
"""
self._compile_started = True
self.do_init()
self._compile_finished = True
@property
def class_attribute(self):
"""Return the class-bound descriptor corresponding to this
MapperProperty."""
return getattr(self.parent.class_, self.key)
def do_init(self):
"""Perform subclass-specific initialization post-mapper-creation
steps.
This is a template method called by the ``MapperProperty``
object's init() method.
"""
pass
def post_instrument_class(self, mapper):
"""Perform instrumentation adjustments that need to occur
after init() has completed.
"""
pass
def per_property_preprocessors(self, uow):
pass
def is_primary(self):
"""Return True if this ``MapperProperty``'s mapper is the
primary mapper for its class.
This flag is used to indicate that the ``MapperProperty`` can
define attribute instrumentation for the class at the class
level (as opposed to the individual instance level).
"""
return not self.parent.non_primary
def merge(self, session, source_state, source_dict, dest_state,
dest_dict, load, _recursive):
"""Merge the attribute represented by this ``MapperProperty``
from source to destination object"""
pass
def compare(self, operator, value, **kw):
"""Return a compare operation for the columns represented by
this ``MapperProperty`` to the given value, which may be a
column value or an instance. 'operator' is an operator from
the operators module, or from sql.Comparator.
By default uses the PropComparator attached to this MapperProperty
under the attribute name "comparator".
"""
return operator(self.comparator, value)
class PropComparator(operators.ColumnOperators):
"""Defines comparison operations for MapperProperty objects.
User-defined subclasses of :class:`.PropComparator` may be created. The
built-in Python comparison and math operator methods, such as
``__eq__()``, ``__lt__()``, ``__add__()``, can be overridden to provide
new operator behavior. The custom :class:`.PropComparator` is passed to
the mapper property via the ``comparator_factory`` argument. In each case,
the appropriate subclass of :class:`.PropComparator` should be used::
from sqlalchemy.orm.properties import \\
ColumnProperty,\\
CompositeProperty,\\
RelationshipProperty
class MyColumnComparator(ColumnProperty.Comparator):
pass
class MyCompositeComparator(CompositeProperty.Comparator):
pass
class MyRelationshipComparator(RelationshipProperty.Comparator):
pass
"""
def __init__(self, prop, mapper, adapter=None):
self.prop = self.property = prop
self.mapper = mapper
self.adapter = adapter
def __clause_element__(self):
raise NotImplementedError("%r" % self)
def adapted(self, adapter):
"""Return a copy of this PropComparator which will use the given
adaption function on the local side of generated expressions.
"""
return self.__class__(self.prop, self.mapper, adapter)
@staticmethod
def any_op(a, b, **kwargs):
return a.any(b, **kwargs)
@staticmethod
def has_op(a, b, **kwargs):
return a.has(b, **kwargs)
@staticmethod
def of_type_op(a, class_):
return a.of_type(class_)
def of_type(self, class_):
"""Redefine this object in terms of a polymorphic subclass.
Returns a new PropComparator from which further criterion can be
evaluated.
e.g.::
query.join(Company.employees.of_type(Engineer)).\\
filter(Engineer.name=='foo')
:param \class_: a class or mapper indicating that criterion will be against
this specific subclass.
"""
return self.operate(PropComparator.of_type_op, class_)
def any(self, criterion=None, **kwargs):
"""Return true if this collection contains any member that meets the
given criterion.
The usual implementation of ``any()`` is
:meth:`.RelationshipProperty.Comparator.any`.
:param criterion: an optional ClauseElement formulated against the
member class' table or attributes.
:param \**kwargs: key/value pairs corresponding to member class attribute
names which will be compared via equality to the corresponding
values.
"""
return self.operate(PropComparator.any_op, criterion, **kwargs)
def has(self, criterion=None, **kwargs):
"""Return true if this element references a member which meets the
given criterion.
The usual implementation of ``has()`` is
:meth:`.RelationshipProperty.Comparator.has`.
:param criterion: an optional ClauseElement formulated against the
member class' table or attributes.
:param \**kwargs: key/value pairs corresponding to member class attribute
names which will be compared via equality to the corresponding
values.
"""
return self.operate(PropComparator.has_op, criterion, **kwargs)
class StrategizedProperty(MapperProperty):
"""A MapperProperty which uses selectable strategies to affect
loading behavior.
There is a single strategy selected by default. Alternate
strategies can be selected at Query time through the usage of
``StrategizedOption`` objects via the Query.options() method.
"""
def _get_context_strategy(self, context, reduced_path):
key = ('loaderstrategy', reduced_path)
if key in context.attributes:
cls = context.attributes[key]
try:
return self._strategies[cls]
except KeyError:
return self.__init_strategy(cls)
else:
return self.strategy
def _get_strategy(self, cls):
try:
return self._strategies[cls]
except KeyError:
return self.__init_strategy(cls)
def __init_strategy(self, cls):
self._strategies[cls] = strategy = cls(self)
return strategy
def setup(self, context, entity, path, reduced_path, adapter, **kwargs):
self._get_context_strategy(context, reduced_path + (self.key,)).\
setup_query(context, entity, path,
reduced_path, adapter, **kwargs)
def create_row_processor(self, context, path, reduced_path, mapper, row, adapter):
return self._get_context_strategy(context, reduced_path + (self.key,)).\
create_row_processor(context, path,
reduced_path, mapper, row, adapter)
def do_init(self):
self._strategies = {}
self.strategy = self.__init_strategy(self.strategy_class)
def post_instrument_class(self, mapper):
if self.is_primary() and \
not mapper.class_manager._attr_has_impl(self.key):
self.strategy.init_class_attribute(mapper)
def build_path(entity, key, prev=None):
if prev:
return prev + (entity, key)
else:
return (entity, key)
def serialize_path(path):
if path is None:
return None
return zip(
[m.class_ for m in [path[i] for i in range(0, len(path), 2)]],
[path[i] for i in range(1, len(path), 2)] + [None]
)
def deserialize_path(path):
if path is None:
return None
p = tuple(chain(*[(mapperutil.class_mapper(cls), key) for cls, key in path]))
if p and p[-1] is None:
p = p[0:-1]
return p
class MapperOption(object):
"""Describe a modification to a Query."""
propagate_to_loaders = False
"""if True, indicate this option should be carried along
Query object generated by scalar or object lazy loaders.
"""
def process_query(self, query):
pass
def process_query_conditionally(self, query):
"""same as process_query(), except that this option may not
apply to the given query.
Used when secondary loaders resend existing options to a new
Query."""
self.process_query(query)
class PropertyOption(MapperOption):
"""A MapperOption that is applied to a property off the mapper or
one of its child mappers, identified by a dot-separated key
or list of class-bound attributes. """
def __init__(self, key, mapper=None):
self.key = key
self.mapper = mapper
def process_query(self, query):
self._process(query, True)
def process_query_conditionally(self, query):
self._process(query, False)
def _process(self, query, raiseerr):
paths, mappers = self._get_paths(query, raiseerr)
if paths:
self.process_query_property(query, paths, mappers)
def process_query_property(self, query, paths, mappers):
pass
def __getstate__(self):
d = self.__dict__.copy()
d['key'] = ret = []
for token in util.to_list(self.key):
if isinstance(token, PropComparator):
ret.append((token.mapper.class_, token.key))
else:
ret.append(token)
return d
def __setstate__(self, state):
ret = []
for key in state['key']:
if isinstance(key, tuple):
cls, propkey = key
ret.append(getattr(cls, propkey))
else:
ret.append(key)
state['key'] = tuple(ret)
self.__dict__ = state
def _find_entity_prop_comparator(self, query, token, mapper, raiseerr):
if mapperutil._is_aliased_class(mapper):
searchfor = mapper
isa = False
else:
searchfor = mapperutil._class_to_mapper(mapper)
isa = True
for ent in query._mapper_entities:
if searchfor is ent.path_entity or isa \
and searchfor.common_parent(ent.path_entity):
return ent
else:
if raiseerr:
if not list(query._mapper_entities):
raise sa_exc.ArgumentError(
"Query has only expression-based entities - "
"can't find property named '%s'."
% (token, )
)
else:
raise sa_exc.ArgumentError(
"Can't find property '%s' on any entity "
"specified in this Query. Note the full path "
"from root (%s) to target entity must be specified."
% (token, ",".join(str(x) for
x in query._mapper_entities))
)
else:
return None
def _find_entity_basestring(self, query, token, raiseerr):
for ent in query._mapper_entities:
# return only the first _MapperEntity when searching
# based on string prop name. Ideally object
# attributes are used to specify more exactly.
return ent
else:
if raiseerr:
raise sa_exc.ArgumentError(
"Query has only expression-based entities - "
"can't find property named '%s'."
% (token, )
)
else:
return None
def _get_paths(self, query, raiseerr):
path = None
entity = None
l = []
mappers = []
# _current_path implies we're in a
# secondary load with an existing path
current_path = list(query._current_path)
tokens = deque(self.key)
while tokens:
token = tokens.popleft()
if isinstance(token, basestring):
sub_tokens = token.split(".", 1)
token = sub_tokens[0]
tokens.extendleft(sub_tokens[1:])
# exhaust current_path before
# matching tokens to entities
if current_path:
if current_path[1] == token:
current_path = current_path[2:]
continue
else:
return [], []
if not entity:
entity = self._find_entity_basestring(
query,
token,
raiseerr)
if entity is None:
return [], []
path_element = entity.path_entity
mapper = entity.mapper
mappers.append(mapper)
if hasattr(mapper.class_, token):
prop = getattr(mapper.class_, token).property
else:
if raiseerr:
raise sa_exc.ArgumentError(
"Can't find property named '%s' on the "
"mapped entity %s in this Query. " % (
token, mapper)
)
else:
return [], []
elif isinstance(token, PropComparator):
prop = token.property
# exhaust current_path before
# matching tokens to entities
if current_path:
if current_path[0:2] == \
[token.parententity, prop.key]:
current_path = current_path[2:]
continue
else:
return [], []
if not entity:
entity = self._find_entity_prop_comparator(
query,
prop.key,
token.parententity,
raiseerr)
if not entity:
return [], []
path_element = entity.path_entity
mapper = entity.mapper
mappers.append(prop.parent)
else:
raise sa_exc.ArgumentError(
"mapper option expects "
"string key or list of attributes")
assert prop is not None
path = build_path(path_element, prop.key, path)
l.append(path)
if getattr(token, '_of_type', None):
path_element = mapper = token._of_type
else:
path_element = mapper = getattr(prop, 'mapper', None)
if mapper is None and tokens:
raise sa_exc.ArgumentError(
"Attribute '%s' of entity '%s' does not "
"refer to a mapped entity" %
(token, entity)
)
if path_element:
path_element = path_element
if current_path:
# ran out of tokens before
# current_path was exhausted.
assert not tokens
return [], []
return l, mappers
class StrategizedOption(PropertyOption):
"""A MapperOption that affects which LoaderStrategy will be used
for an operation by a StrategizedProperty.
"""
chained = False
def process_query_property(self, query, paths, mappers):
# _get_context_strategy may receive the path in terms of a base
# mapper - e.g. options(eagerload_all(Company.employees,
# Engineer.machines)) in the polymorphic tests leads to
# "(Person, 'machines')" in the path due to the mechanics of how
# the eager strategy builds up the path
if self.chained:
for path in paths:
query._attributes[('loaderstrategy',
_reduce_path(path))] = \
self.get_strategy_class()
else:
query._attributes[('loaderstrategy',
_reduce_path(paths[-1]))] = \
self.get_strategy_class()
def get_strategy_class(self):
raise NotImplementedError()
def _reduce_path(path):
"""Convert a (mapper, path) path to use base mappers.
This is used to allow more open ended selection of loader strategies, i.e.
Mapper -> prop1 -> Subclass -> prop2, where Subclass is a sub-mapper
of the mapper referenced by Mapper.prop1.
"""
return tuple([i % 2 != 0 and
element or
getattr(element, 'base_mapper', element)
for i, element in enumerate(path)])
class LoaderStrategy(object):
"""Describe the loading behavior of a StrategizedProperty object.
The ``LoaderStrategy`` interacts with the querying process in three
ways:
* it controls the configuration of the ``InstrumentedAttribute``
placed on a class to handle the behavior of the attribute. this
may involve setting up class-level callable functions to fire
off a select operation when the attribute is first accessed
(i.e. a lazy load)
* it processes the ``QueryContext`` at statement construction time,
where it can modify the SQL statement that is being produced.
Simple column attributes may add their represented column to the
list of selected columns, *eager loading* properties may add
``LEFT OUTER JOIN`` clauses to the statement.
* It produces "row processor" functions at result fetching time.
These "row processor" functions populate a particular attribute
on a particular mapped instance.
"""
def __init__(self, parent):
self.parent_property = parent
self.is_class_level = False
self.parent = self.parent_property.parent
self.key = self.parent_property.key
# TODO: there's no particular reason we need
# the separate .init() method at this point.
# It's possible someone has written their
# own LS object.
self.init()
def init(self):
raise NotImplementedError("LoaderStrategy")
def init_class_attribute(self, mapper):
pass
def setup_query(self, context, entity, path, reduced_path, adapter, **kwargs):
pass
def create_row_processor(self, context, path, reduced_path, mapper,
row, adapter):
"""Return row processing functions which fulfill the contract
specified by MapperProperty.create_row_processor.
StrategizedProperty delegates its create_row_processor method
directly to this method. """
return None, None, None
def __str__(self):
return str(self.parent_property)
def debug_callable(self, fn, logger, announcement, logfn):
if announcement:
logger.debug(announcement)
if logfn:
def call(*args, **kwargs):
logger.debug(logfn(*args, **kwargs))
return fn(*args, **kwargs)
return call
else:
return fn
class InstrumentationManager(object):
"""User-defined class instrumentation extension.
:class:`.InstrumentationManager` can be subclassed in order
to change
how class instrumentation proceeds. This class exists for
the purposes of integration with other object management
frameworks which would like to entirely modify the
instrumentation methodology of the ORM, and is not intended
for regular usage. For interception of class instrumentation
events, see :class:`.InstrumentationEvents`.
For an example of :class:`.InstrumentationManager`, see the
example :ref:`examples_instrumentation`.
The API for this class should be considered as semi-stable,
and may change slightly with new releases.
"""
# r4361 added a mandatory (cls) constructor to this interface.
# given that, perhaps class_ should be dropped from all of these
# signatures.
def __init__(self, class_):
pass
def manage(self, class_, manager):
setattr(class_, '_default_class_manager', manager)
def dispose(self, class_, manager):
delattr(class_, '_default_class_manager')
def manager_getter(self, class_):
def get(cls):
return cls._default_class_manager
return get
def instrument_attribute(self, class_, key, inst):
pass
def post_configure_attribute(self, class_, key, inst):
pass
def install_descriptor(self, class_, key, inst):
setattr(class_, key, inst)
def uninstall_descriptor(self, class_, key):
delattr(class_, key)
def install_member(self, class_, key, implementation):
setattr(class_, key, implementation)
def uninstall_member(self, class_, key):
delattr(class_, key)
def instrument_collection_class(self, class_, key, collection_class):
global collections
if collections is None:
from sqlalchemy.orm import collections
return collections.prepare_instrumentation(collection_class)
def get_instance_dict(self, class_, instance):
return instance.__dict__
def initialize_instance_dict(self, class_, instance):
pass
def install_state(self, class_, instance, state):
setattr(instance, '_default_state', state)
def remove_state(self, class_, instance):
delattr(instance, '_default_state')
def state_getter(self, class_):
return lambda instance: getattr(instance, '_default_state')
def dict_getter(self, class_):
return lambda inst: self.get_instance_dict(class_, inst)
|