1687 lines
54 KiB
Python
1687 lines
54 KiB
Python
# Copyright (C) 2005-2019 the SQLAlchemy authors and contributors
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# <see AUTHORS file>
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#
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# This module is part of SQLAlchemy and is released under
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# the MIT License: http://www.opensource.org/licenses/mit-license.php
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"""
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"""
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from . import util as orm_util
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from .attributes import QueryableAttribute
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from .base import _class_to_mapper
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from .base import _is_aliased_class
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from .base import _is_mapped_class
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from .base import InspectionAttr
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from .interfaces import MapperOption
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from .interfaces import PropComparator
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from .path_registry import _DEFAULT_TOKEN
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from .path_registry import _WILDCARD_TOKEN
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from .path_registry import PathRegistry
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from .path_registry import TokenRegistry
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from .util import _orm_full_deannotate
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from .. import exc as sa_exc
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from .. import inspect
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from .. import util
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from ..sql import expression as sql_expr
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from ..sql.base import _generative
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from ..sql.base import Generative
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class Load(Generative, MapperOption):
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"""Represents loader options which modify the state of a
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:class:`.Query` in order to affect how various mapped attributes are
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loaded.
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The :class:`.Load` object is in most cases used implicitly behind the
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scenes when one makes use of a query option like :func:`.joinedload`,
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:func:`.defer`, or similar. However, the :class:`.Load` object
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can also be used directly, and in some cases can be useful.
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To use :class:`.Load` directly, instantiate it with the target mapped
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class as the argument. This style of usage is
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useful when dealing with a :class:`.Query` that has multiple entities::
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myopt = Load(MyClass).joinedload("widgets")
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The above ``myopt`` can now be used with :meth:`.Query.options`, where it
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will only take effect for the ``MyClass`` entity::
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session.query(MyClass, MyOtherClass).options(myopt)
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One case where :class:`.Load` is useful as public API is when specifying
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"wildcard" options that only take effect for a certain class::
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session.query(Order).options(Load(Order).lazyload('*'))
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Above, all relationships on ``Order`` will be lazy-loaded, but other
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attributes on those descendant objects will load using their normal
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loader strategy.
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.. seealso::
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:ref:`deferred_options`
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:ref:`deferred_loading_w_multiple`
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:ref:`relationship_loader_options`
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"""
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def __init__(self, entity):
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insp = inspect(entity)
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self.path = insp._path_registry
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# note that this .context is shared among all descendant
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# Load objects
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self.context = util.OrderedDict()
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self.local_opts = {}
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self._of_type = None
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self.is_class_strategy = False
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@classmethod
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def for_existing_path(cls, path):
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load = cls.__new__(cls)
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load.path = path
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load.context = {}
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load.local_opts = {}
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load._of_type = None
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return load
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def _generate_cache_key(self, path):
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if path.path[0].is_aliased_class:
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return False
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serialized = []
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for (key, loader_path), obj in self.context.items():
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if key != "loader":
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continue
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for local_elem, obj_elem in zip(self.path.path, loader_path):
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if local_elem is not obj_elem:
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break
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else:
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endpoint = obj._of_type or obj.path.path[-1]
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chopped = self._chop_path(loader_path, path)
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if (
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# means loader_path and path are unrelated,
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# this does not need to be part of a cache key
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chopped
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is None
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) or (
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# means no additional path with loader_path + path
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# and the endpoint isn't using of_type so isn't modified
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# into an alias or other unsafe entity
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not chopped
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and not obj._of_type
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):
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continue
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serialized_path = []
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for token in chopped:
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if isinstance(token, util.string_types):
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serialized_path.append(token)
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elif token.is_aliased_class:
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return False
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elif token.is_property:
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serialized_path.append(token.key)
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else:
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assert token.is_mapper
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serialized_path.append(token.class_)
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if not serialized_path or endpoint != serialized_path[-1]:
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if endpoint.is_mapper:
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serialized_path.append(endpoint.class_)
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elif endpoint.is_aliased_class:
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return False
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serialized.append(
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(
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tuple(serialized_path)
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+ (obj.strategy or ())
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+ (
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tuple(
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[
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(key, obj.local_opts[key])
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for key in sorted(obj.local_opts)
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]
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)
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if obj.local_opts
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else ()
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)
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)
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)
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if not serialized:
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return None
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else:
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return tuple(serialized)
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def _generate(self):
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cloned = super(Load, self)._generate()
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cloned.local_opts = {}
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return cloned
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is_opts_only = False
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is_class_strategy = False
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strategy = None
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propagate_to_loaders = False
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def process_query(self, query):
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self._process(query, True)
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def process_query_conditionally(self, query):
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self._process(query, False)
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def _process(self, query, raiseerr):
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current_path = query._current_path
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if current_path:
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for (token, start_path), loader in self.context.items():
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chopped_start_path = self._chop_path(start_path, current_path)
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if chopped_start_path is not None:
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query._attributes[(token, chopped_start_path)] = loader
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else:
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query._attributes.update(self.context)
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def _generate_path(
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self, path, attr, for_strategy, wildcard_key, raiseerr=True
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):
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existing_of_type = self._of_type
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self._of_type = None
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if raiseerr and not path.has_entity:
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if isinstance(path, TokenRegistry):
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raise sa_exc.ArgumentError(
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"Wildcard token cannot be followed by another entity"
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)
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else:
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raise sa_exc.ArgumentError(
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"Mapped attribute '%s' does not "
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"refer to a mapped entity" % (path.prop,)
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)
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if isinstance(attr, util.string_types):
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default_token = attr.endswith(_DEFAULT_TOKEN)
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if attr.endswith(_WILDCARD_TOKEN) or default_token:
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if default_token:
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self.propagate_to_loaders = False
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if wildcard_key:
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attr = "%s:%s" % (wildcard_key, attr)
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# TODO: AliasedInsp inside the path for of_type is not
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# working for a with_polymorphic entity because the
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# relationship loaders don't render the with_poly into the
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# path. See #4469 which will try to improve this
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if existing_of_type and not existing_of_type.is_aliased_class:
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path = path.parent[existing_of_type]
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path = path.token(attr)
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self.path = path
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return path
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if existing_of_type:
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ent = inspect(existing_of_type)
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else:
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ent = path.entity
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try:
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# use getattr on the class to work around
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# synonyms, hybrids, etc.
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attr = getattr(ent.class_, attr)
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except AttributeError:
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if raiseerr:
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raise sa_exc.ArgumentError(
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'Can\'t find property named "%s" on '
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"%s in this Query." % (attr, ent)
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)
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else:
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return None
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else:
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attr = found_property = attr.property
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path = path[attr]
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elif _is_mapped_class(attr):
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# TODO: this does not appear to be a valid codepath. "attr"
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# would never be a mapper. This block is present in 1.2
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# as well however does not seem to be accessed in any tests.
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if not orm_util._entity_corresponds_to_use_path_impl(
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attr.parent, path[-1]
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):
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if raiseerr:
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raise sa_exc.ArgumentError(
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"Attribute '%s' does not "
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"link from element '%s'" % (attr, path.entity)
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)
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else:
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return None
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else:
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prop = found_property = attr.property
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if not orm_util._entity_corresponds_to_use_path_impl(
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attr.parent, path[-1]
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):
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if raiseerr:
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raise sa_exc.ArgumentError(
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'Attribute "%s" does not '
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'link from element "%s".%s'
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% (
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attr,
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path.entity,
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(
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" Did you mean to use "
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"%s.of_type(%s)?"
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% (path[-2], attr.class_.__name__)
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if len(path) > 1
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and path.entity.is_mapper
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and attr.parent.is_aliased_class
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else ""
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),
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)
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)
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else:
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return None
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if getattr(attr, "_of_type", None):
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ac = attr._of_type
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ext_info = of_type_info = inspect(ac)
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existing = path.entity_path[prop].get(
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self.context, "path_with_polymorphic"
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)
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if not ext_info.is_aliased_class:
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ac = orm_util.with_polymorphic(
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ext_info.mapper.base_mapper,
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ext_info.mapper,
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aliased=True,
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_use_mapper_path=True,
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_existing_alias=existing,
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)
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ext_info = inspect(ac)
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path.entity_path[prop].set(
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self.context, "path_with_polymorphic", ext_info
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)
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path = path[prop][ext_info]
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self._of_type = of_type_info
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else:
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path = path[prop]
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if for_strategy is not None:
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found_property._get_strategy(for_strategy)
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if path.has_entity:
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path = path.entity_path
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self.path = path
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return path
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def __str__(self):
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return "Load(strategy=%r)" % (self.strategy,)
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def _coerce_strat(self, strategy):
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if strategy is not None:
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strategy = tuple(sorted(strategy.items()))
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return strategy
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def _apply_to_parent(self, parent, applied, bound):
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raise NotImplementedError(
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"Only 'unbound' loader options may be used with the "
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"Load.options() method"
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)
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@_generative
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def options(self, *opts):
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r"""Apply a series of options as sub-options to this :class:`.Load`
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object.
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E.g.::
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query = session.query(Author)
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query = query.options(
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joinedload(Author.book).options(
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load_only("summary", "excerpt"),
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joinedload(Book.citations).options(
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joinedload(Citation.author)
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)
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)
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)
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:param \*opts: A series of loader option objects (ultimately
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:class:`.Load` objects) which should be applied to the path
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specified by this :class:`.Load` object.
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.. versionadded:: 1.3.6
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.. seealso::
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:func:`.defaultload`
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:ref:`relationship_loader_options`
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:ref:`deferred_loading_w_multiple`
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"""
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apply_cache = {}
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bound = not isinstance(self, _UnboundLoad)
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if bound:
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raise NotImplementedError(
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"The options() method is currently only supported "
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"for 'unbound' loader options"
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)
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for opt in opts:
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opt._apply_to_parent(self, apply_cache, bound)
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@_generative
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def set_relationship_strategy(
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self, attr, strategy, propagate_to_loaders=True
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):
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strategy = self._coerce_strat(strategy)
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self.is_class_strategy = False
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self.propagate_to_loaders = propagate_to_loaders
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# if the path is a wildcard, this will set propagate_to_loaders=False
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self._generate_path(self.path, attr, strategy, "relationship")
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self.strategy = strategy
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if strategy is not None:
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self._set_path_strategy()
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@_generative
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def set_column_strategy(self, attrs, strategy, opts=None, opts_only=False):
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strategy = self._coerce_strat(strategy)
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self.is_class_strategy = False
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for attr in attrs:
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cloned = self._generate()
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cloned.strategy = strategy
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cloned._generate_path(self.path, attr, strategy, "column")
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cloned.propagate_to_loaders = True
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if opts:
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cloned.local_opts.update(opts)
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if opts_only:
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cloned.is_opts_only = True
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cloned._set_path_strategy()
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self.is_class_strategy = False
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@_generative
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def set_generic_strategy(self, attrs, strategy):
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strategy = self._coerce_strat(strategy)
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for attr in attrs:
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path = self._generate_path(self.path, attr, strategy, None)
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cloned = self._generate()
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cloned.strategy = strategy
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cloned.path = path
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cloned.propagate_to_loaders = True
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cloned._set_path_strategy()
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@_generative
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def set_class_strategy(self, strategy, opts):
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strategy = self._coerce_strat(strategy)
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cloned = self._generate()
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cloned.is_class_strategy = True
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path = cloned._generate_path(self.path, None, strategy, None)
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cloned.strategy = strategy
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cloned.path = path
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cloned.propagate_to_loaders = True
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cloned._set_path_strategy()
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cloned.local_opts.update(opts)
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def _set_for_path(self, context, path, replace=True, merge_opts=False):
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if merge_opts or not replace:
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existing = path.get(self.context, "loader")
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if existing:
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if merge_opts:
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existing.local_opts.update(self.local_opts)
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else:
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path.set(context, "loader", self)
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else:
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existing = path.get(self.context, "loader")
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path.set(context, "loader", self)
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if existing and existing.is_opts_only:
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self.local_opts.update(existing.local_opts)
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def _set_path_strategy(self):
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if not self.is_class_strategy and self.path.has_entity:
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effective_path = self.path.parent
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else:
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effective_path = self.path
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if effective_path.is_token:
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for path in effective_path.generate_for_superclasses():
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self._set_for_path(
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self.context,
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path,
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replace=True,
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merge_opts=self.is_opts_only,
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)
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else:
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self._set_for_path(
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self.context,
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effective_path,
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replace=True,
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merge_opts=self.is_opts_only,
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)
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def __getstate__(self):
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d = self.__dict__.copy()
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d["context"] = PathRegistry.serialize_context_dict(
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d["context"], ("loader",)
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)
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d["path"] = self.path.serialize()
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return d
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def __setstate__(self, state):
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self.__dict__.update(state)
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self.path = PathRegistry.deserialize(self.path)
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self.context = PathRegistry.deserialize_context_dict(self.context)
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def _chop_path(self, to_chop, path):
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i = -1
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for i, (c_token, p_token) in enumerate(zip(to_chop, path.path)):
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if isinstance(c_token, util.string_types):
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# TODO: this is approximated from the _UnboundLoad
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# version and probably has issues, not fully covered.
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if i == 0 and c_token.endswith(":" + _DEFAULT_TOKEN):
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return to_chop
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elif (
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c_token != "relationship:%s" % (_WILDCARD_TOKEN,)
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and c_token != p_token.key
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):
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return None
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if c_token is p_token:
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continue
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elif (
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isinstance(c_token, InspectionAttr)
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and c_token.is_mapper
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and p_token.is_mapper
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and c_token.isa(p_token)
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):
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continue
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else:
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return None
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return to_chop[i + 1 :]
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|
|
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class _UnboundLoad(Load):
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"""Represent a loader option that isn't tied to a root entity.
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The loader option will produce an entity-linked :class:`.Load`
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object when it is passed :meth:`.Query.options`.
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This provides compatibility with the traditional system
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of freestanding options, e.g. ``joinedload('x.y.z')``.
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"""
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def __init__(self):
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self.path = ()
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self._to_bind = []
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self.local_opts = {}
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_is_chain_link = False
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def _generate_cache_key(self, path):
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serialized = ()
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for val in self._to_bind:
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for local_elem, val_elem in zip(self.path, val.path):
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if local_elem is not val_elem:
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break
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else:
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opt = val._bind_loader([path.path[0]], None, None, False)
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if opt:
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c_key = opt._generate_cache_key(path)
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if c_key is False:
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return False
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elif c_key:
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serialized += c_key
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if not serialized:
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return None
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else:
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return serialized
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|
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def _set_path_strategy(self):
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self._to_bind.append(self)
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|
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def _apply_to_parent(self, parent, applied, bound):
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if self in applied:
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return applied[self]
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cloned = self._generate()
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applied[self] = cloned
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|
|
cloned.strategy = self.strategy
|
|
if self.path:
|
|
attr = self.path[-1]
|
|
if isinstance(attr, util.string_types) and attr.endswith(
|
|
_DEFAULT_TOKEN
|
|
):
|
|
attr = attr.split(":")[0] + ":" + _WILDCARD_TOKEN
|
|
cloned._generate_path(
|
|
parent.path + self.path[0:-1], attr, self.strategy, None
|
|
)
|
|
|
|
# these assertions can go away once the "sub options" API is
|
|
# mature
|
|
assert cloned.propagate_to_loaders == self.propagate_to_loaders
|
|
assert cloned.is_class_strategy == self.is_class_strategy
|
|
assert cloned.is_opts_only == self.is_opts_only
|
|
|
|
new_to_bind = {
|
|
elem._apply_to_parent(parent, applied, bound)
|
|
for elem in self._to_bind
|
|
}
|
|
cloned._to_bind = parent._to_bind
|
|
cloned._to_bind.extend(new_to_bind)
|
|
cloned.local_opts.update(self.local_opts)
|
|
|
|
return cloned
|
|
|
|
def _generate_path(self, path, attr, for_strategy, wildcard_key):
|
|
if (
|
|
wildcard_key
|
|
and isinstance(attr, util.string_types)
|
|
and attr in (_WILDCARD_TOKEN, _DEFAULT_TOKEN)
|
|
):
|
|
if attr == _DEFAULT_TOKEN:
|
|
self.propagate_to_loaders = False
|
|
attr = "%s:%s" % (wildcard_key, attr)
|
|
if path and _is_mapped_class(path[-1]) and not self.is_class_strategy:
|
|
path = path[0:-1]
|
|
if attr:
|
|
path = path + (attr,)
|
|
self.path = path
|
|
return path
|
|
|
|
def __getstate__(self):
|
|
d = self.__dict__.copy()
|
|
d["path"] = self._serialize_path(self.path, filter_aliased_class=True)
|
|
return d
|
|
|
|
def __setstate__(self, state):
|
|
ret = []
|
|
for key in state["path"]:
|
|
if isinstance(key, tuple):
|
|
if len(key) == 2:
|
|
# support legacy
|
|
cls, propkey = key
|
|
of_type = None
|
|
else:
|
|
cls, propkey, of_type = key
|
|
prop = getattr(cls, propkey)
|
|
if of_type:
|
|
prop = prop.of_type(of_type)
|
|
ret.append(prop)
|
|
else:
|
|
ret.append(key)
|
|
state["path"] = tuple(ret)
|
|
self.__dict__ = state
|
|
|
|
def _process(self, query, raiseerr):
|
|
dedupes = query._attributes["_unbound_load_dedupes"]
|
|
for val in self._to_bind:
|
|
if val not in dedupes:
|
|
dedupes.add(val)
|
|
val._bind_loader(
|
|
[ent.entity_zero for ent in query._mapper_entities],
|
|
query._current_path,
|
|
query._attributes,
|
|
raiseerr,
|
|
)
|
|
|
|
@classmethod
|
|
def _from_keys(cls, meth, keys, chained, kw):
|
|
opt = _UnboundLoad()
|
|
|
|
def _split_key(key):
|
|
if isinstance(key, util.string_types):
|
|
# coerce fooload('*') into "default loader strategy"
|
|
if key == _WILDCARD_TOKEN:
|
|
return (_DEFAULT_TOKEN,)
|
|
# coerce fooload(".*") into "wildcard on default entity"
|
|
elif key.startswith("." + _WILDCARD_TOKEN):
|
|
key = key[1:]
|
|
return key.split(".")
|
|
else:
|
|
return (key,)
|
|
|
|
all_tokens = [token for key in keys for token in _split_key(key)]
|
|
|
|
for token in all_tokens[0:-1]:
|
|
if chained:
|
|
opt = meth(opt, token, **kw)
|
|
else:
|
|
opt = opt.defaultload(token)
|
|
opt._is_chain_link = True
|
|
|
|
opt = meth(opt, all_tokens[-1], **kw)
|
|
opt._is_chain_link = False
|
|
|
|
return opt
|
|
|
|
def _chop_path(self, to_chop, path):
|
|
i = -1
|
|
for i, (c_token, (p_entity, p_prop)) in enumerate(
|
|
zip(to_chop, path.pairs())
|
|
):
|
|
if isinstance(c_token, util.string_types):
|
|
if i == 0 and c_token.endswith(":" + _DEFAULT_TOKEN):
|
|
return to_chop
|
|
elif (
|
|
c_token != "relationship:%s" % (_WILDCARD_TOKEN,)
|
|
and c_token != p_prop.key
|
|
):
|
|
return None
|
|
elif isinstance(c_token, PropComparator):
|
|
if c_token.property is not p_prop or (
|
|
c_token._parententity is not p_entity
|
|
and (
|
|
not c_token._parententity.is_mapper
|
|
or not c_token._parententity.isa(p_entity)
|
|
)
|
|
):
|
|
return None
|
|
else:
|
|
i += 1
|
|
|
|
return to_chop[i:]
|
|
|
|
def _serialize_path(self, path, filter_aliased_class=False):
|
|
ret = []
|
|
for token in path:
|
|
if isinstance(token, QueryableAttribute):
|
|
if (
|
|
filter_aliased_class
|
|
and token._of_type
|
|
and inspect(token._of_type).is_aliased_class
|
|
):
|
|
ret.append((token._parentmapper.class_, token.key, None))
|
|
else:
|
|
ret.append(
|
|
(token._parentmapper.class_, token.key, token._of_type)
|
|
)
|
|
elif isinstance(token, PropComparator):
|
|
ret.append((token._parentmapper.class_, token.key, None))
|
|
else:
|
|
ret.append(token)
|
|
return ret
|
|
|
|
def _bind_loader(self, entities, current_path, context, raiseerr):
|
|
"""Convert from an _UnboundLoad() object into a Load() object.
|
|
|
|
The _UnboundLoad() uses an informal "path" and does not necessarily
|
|
refer to a lead entity as it may use string tokens. The Load()
|
|
OTOH refers to a complete path. This method reconciles from a
|
|
given Query into a Load.
|
|
|
|
Example::
|
|
|
|
|
|
query = session.query(User).options(
|
|
joinedload("orders").joinedload("items"))
|
|
|
|
The above options will be an _UnboundLoad object along the lines
|
|
of (note this is not the exact API of _UnboundLoad)::
|
|
|
|
_UnboundLoad(
|
|
_to_bind=[
|
|
_UnboundLoad(["orders"], {"lazy": "joined"}),
|
|
_UnboundLoad(["orders", "items"], {"lazy": "joined"}),
|
|
]
|
|
)
|
|
|
|
After this method, we get something more like this (again this is
|
|
not exact API)::
|
|
|
|
Load(
|
|
User,
|
|
(User, User.orders.property))
|
|
Load(
|
|
User,
|
|
(User, User.orders.property, Order, Order.items.property))
|
|
|
|
"""
|
|
|
|
start_path = self.path
|
|
|
|
if self.is_class_strategy and current_path:
|
|
start_path += (entities[0],)
|
|
|
|
# _current_path implies we're in a
|
|
# secondary load with an existing path
|
|
|
|
if current_path:
|
|
start_path = self._chop_path(start_path, current_path)
|
|
|
|
if not start_path:
|
|
return None
|
|
|
|
# look at the first token and try to locate within the Query
|
|
# what entity we are referring towards.
|
|
token = start_path[0]
|
|
|
|
if isinstance(token, util.string_types):
|
|
entity = self._find_entity_basestring(entities, token, raiseerr)
|
|
elif isinstance(token, PropComparator):
|
|
prop = token.property
|
|
entity = self._find_entity_prop_comparator(
|
|
entities, prop, token._parententity, raiseerr
|
|
)
|
|
elif self.is_class_strategy and _is_mapped_class(token):
|
|
entity = inspect(token)
|
|
if entity not in entities:
|
|
entity = None
|
|
else:
|
|
raise sa_exc.ArgumentError(
|
|
"mapper option expects " "string key or list of attributes"
|
|
)
|
|
|
|
if not entity:
|
|
return
|
|
|
|
path_element = entity
|
|
|
|
# transfer our entity-less state into a Load() object
|
|
# with a real entity path. Start with the lead entity
|
|
# we just located, then go through the rest of our path
|
|
# tokens and populate into the Load().
|
|
loader = Load(path_element)
|
|
if context is not None:
|
|
loader.context = context
|
|
else:
|
|
context = loader.context
|
|
|
|
loader.strategy = self.strategy
|
|
loader.is_opts_only = self.is_opts_only
|
|
loader.is_class_strategy = self.is_class_strategy
|
|
|
|
path = loader.path
|
|
|
|
if not loader.is_class_strategy:
|
|
for idx, token in enumerate(start_path):
|
|
if not loader._generate_path(
|
|
loader.path,
|
|
token,
|
|
self.strategy if idx == len(start_path) - 1 else None,
|
|
None,
|
|
raiseerr,
|
|
):
|
|
return
|
|
|
|
loader.local_opts.update(self.local_opts)
|
|
|
|
if not loader.is_class_strategy and loader.path.has_entity:
|
|
effective_path = loader.path.parent
|
|
else:
|
|
effective_path = loader.path
|
|
|
|
# prioritize "first class" options over those
|
|
# that were "links in the chain", e.g. "x" and "y" in
|
|
# someload("x.y.z") versus someload("x") / someload("x.y")
|
|
|
|
if effective_path.is_token:
|
|
for path in effective_path.generate_for_superclasses():
|
|
loader._set_for_path(
|
|
context,
|
|
path,
|
|
replace=not self._is_chain_link,
|
|
merge_opts=self.is_opts_only,
|
|
)
|
|
else:
|
|
loader._set_for_path(
|
|
context,
|
|
effective_path,
|
|
replace=not self._is_chain_link,
|
|
merge_opts=self.is_opts_only,
|
|
)
|
|
|
|
return loader
|
|
|
|
def _find_entity_prop_comparator(self, entities, prop, mapper, raiseerr):
|
|
if _is_aliased_class(mapper):
|
|
searchfor = mapper
|
|
else:
|
|
searchfor = _class_to_mapper(mapper)
|
|
for ent in entities:
|
|
if orm_util._entity_corresponds_to(ent, searchfor):
|
|
return ent
|
|
else:
|
|
if raiseerr:
|
|
if not list(entities):
|
|
raise sa_exc.ArgumentError(
|
|
"Query has only expression-based entities, "
|
|
'which do not apply to %s "%s"'
|
|
% (util.clsname_as_plain_name(type(prop)), prop)
|
|
)
|
|
else:
|
|
raise sa_exc.ArgumentError(
|
|
'Mapped attribute "%s" does not apply to any of the '
|
|
"root entities in this query, e.g. %s. Please "
|
|
"specify the full path "
|
|
"from one of the root entities to the target "
|
|
"attribute. "
|
|
% (prop, ", ".join(str(x) for x in entities))
|
|
)
|
|
else:
|
|
return None
|
|
|
|
def _find_entity_basestring(self, entities, token, raiseerr):
|
|
if token.endswith(":" + _WILDCARD_TOKEN):
|
|
if len(list(entities)) != 1:
|
|
if raiseerr:
|
|
raise sa_exc.ArgumentError(
|
|
"Can't apply wildcard ('*') or load_only() "
|
|
"loader option to multiple entities %s. Specify "
|
|
"loader options for each entity individually, such "
|
|
"as %s."
|
|
% (
|
|
", ".join(str(ent) for ent in entities),
|
|
", ".join(
|
|
"Load(%s).some_option('*')" % ent
|
|
for ent in entities
|
|
),
|
|
)
|
|
)
|
|
elif token.endswith(_DEFAULT_TOKEN):
|
|
raiseerr = False
|
|
|
|
for ent in 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
|
|
|
|
|
|
class loader_option(object):
|
|
def __init__(self):
|
|
pass
|
|
|
|
def __call__(self, fn):
|
|
self.name = name = fn.__name__
|
|
self.fn = fn
|
|
if hasattr(Load, name):
|
|
raise TypeError("Load class already has a %s method." % (name))
|
|
setattr(Load, name, fn)
|
|
|
|
return self
|
|
|
|
def _add_unbound_fn(self, fn):
|
|
self._unbound_fn = fn
|
|
fn_doc = self.fn.__doc__
|
|
self.fn.__doc__ = """Produce a new :class:`.Load` object with the
|
|
:func:`.orm.%(name)s` option applied.
|
|
|
|
See :func:`.orm.%(name)s` for usage examples.
|
|
|
|
""" % {
|
|
"name": self.name
|
|
}
|
|
|
|
fn.__doc__ = fn_doc
|
|
return self
|
|
|
|
def _add_unbound_all_fn(self, fn):
|
|
fn.__doc__ = """Produce a standalone "all" option for :func:`.orm.%(name)s`.
|
|
|
|
.. deprecated:: 0.9
|
|
|
|
The :func:`.%(name)s_all` function is deprecated, and will be removed
|
|
in a future release. Please use method chaining with :func:`.%(name)s`
|
|
instead, as in::
|
|
|
|
session.query(MyClass).options(
|
|
%(name)s("someattribute").%(name)s("anotherattribute")
|
|
)
|
|
|
|
""" % {
|
|
"name": self.name
|
|
}
|
|
fn = util.deprecated(
|
|
"0.9",
|
|
"The :func:`.%(name)s_all` function is deprecated, and will be "
|
|
"removed in a future release. Please use method chaining with "
|
|
":func:`.%(name)s` instead" % {"name": self.name},
|
|
add_deprecation_to_docstring=False,
|
|
)(fn)
|
|
|
|
self._unbound_all_fn = fn
|
|
return self
|
|
|
|
|
|
@loader_option()
|
|
def contains_eager(loadopt, attr, alias=None):
|
|
r"""Indicate that the given attribute should be eagerly loaded from
|
|
columns stated manually in the query.
|
|
|
|
This function is part of the :class:`.Load` interface and supports
|
|
both method-chained and standalone operation.
|
|
|
|
The option is used in conjunction with an explicit join that loads
|
|
the desired rows, i.e.::
|
|
|
|
sess.query(Order).\
|
|
join(Order.user).\
|
|
options(contains_eager(Order.user))
|
|
|
|
The above query would join from the ``Order`` entity to its related
|
|
``User`` entity, and the returned ``Order`` objects would have the
|
|
``Order.user`` attribute pre-populated.
|
|
|
|
:func:`.contains_eager` also accepts an `alias` argument, which is the
|
|
string name of an alias, an :func:`~sqlalchemy.sql.expression.alias`
|
|
construct, or an :func:`~sqlalchemy.orm.aliased` construct. Use this when
|
|
the eagerly-loaded rows are to come from an aliased table::
|
|
|
|
user_alias = aliased(User)
|
|
sess.query(Order).\
|
|
join((user_alias, Order.user)).\
|
|
options(contains_eager(Order.user, alias=user_alias))
|
|
|
|
When using :func:`.contains_eager` in conjunction with inherited
|
|
subclasses, the :meth:`.RelationshipProperty.of_type` modifier should
|
|
also be used in order to set up the pathing properly::
|
|
|
|
sess.query(Company).\
|
|
outerjoin(Company.employees.of_type(Manager)).\
|
|
options(
|
|
contains_eager(
|
|
Company.employees.of_type(Manager),
|
|
alias=Manager)
|
|
)
|
|
|
|
.. seealso::
|
|
|
|
:ref:`loading_toplevel`
|
|
|
|
:ref:`contains_eager`
|
|
|
|
"""
|
|
if alias is not None:
|
|
if not isinstance(alias, str):
|
|
info = inspect(alias)
|
|
alias = info.selectable
|
|
|
|
elif getattr(attr, "_of_type", None):
|
|
ot = inspect(attr._of_type)
|
|
alias = ot.selectable
|
|
|
|
cloned = loadopt.set_relationship_strategy(
|
|
attr, {"lazy": "joined"}, propagate_to_loaders=False
|
|
)
|
|
cloned.local_opts["eager_from_alias"] = alias
|
|
return cloned
|
|
|
|
|
|
@contains_eager._add_unbound_fn
|
|
def contains_eager(*keys, **kw):
|
|
return _UnboundLoad()._from_keys(
|
|
_UnboundLoad.contains_eager, keys, True, kw
|
|
)
|
|
|
|
|
|
@loader_option()
|
|
def load_only(loadopt, *attrs):
|
|
"""Indicate that for a particular entity, only the given list
|
|
of column-based attribute names should be loaded; all others will be
|
|
deferred.
|
|
|
|
This function is part of the :class:`.Load` interface and supports
|
|
both method-chained and standalone operation.
|
|
|
|
Example - given a class ``User``, load only the ``name`` and ``fullname``
|
|
attributes::
|
|
|
|
session.query(User).options(load_only("name", "fullname"))
|
|
|
|
Example - given a relationship ``User.addresses -> Address``, specify
|
|
subquery loading for the ``User.addresses`` collection, but on each
|
|
``Address`` object load only the ``email_address`` attribute::
|
|
|
|
session.query(User).options(
|
|
subqueryload("addresses").load_only("email_address")
|
|
)
|
|
|
|
For a :class:`.Query` that has multiple entities, the lead entity can be
|
|
specifically referred to using the :class:`.Load` constructor::
|
|
|
|
session.query(User, Address).join(User.addresses).options(
|
|
Load(User).load_only("name", "fullname"),
|
|
Load(Address).load_only("email_addres")
|
|
)
|
|
|
|
|
|
.. versionadded:: 0.9.0
|
|
|
|
"""
|
|
cloned = loadopt.set_column_strategy(
|
|
attrs, {"deferred": False, "instrument": True}
|
|
)
|
|
cloned.set_column_strategy(
|
|
"*", {"deferred": True, "instrument": True}, {"undefer_pks": True}
|
|
)
|
|
return cloned
|
|
|
|
|
|
@load_only._add_unbound_fn
|
|
def load_only(*attrs):
|
|
return _UnboundLoad().load_only(*attrs)
|
|
|
|
|
|
@loader_option()
|
|
def joinedload(loadopt, attr, innerjoin=None):
|
|
"""Indicate that the given attribute should be loaded using joined
|
|
eager loading.
|
|
|
|
This function is part of the :class:`.Load` interface and supports
|
|
both method-chained and standalone operation.
|
|
|
|
examples::
|
|
|
|
# joined-load the "orders" collection on "User"
|
|
query(User).options(joinedload(User.orders))
|
|
|
|
# joined-load Order.items and then Item.keywords
|
|
query(Order).options(
|
|
joinedload(Order.items).joinedload(Item.keywords))
|
|
|
|
# lazily load Order.items, but when Items are loaded,
|
|
# joined-load the keywords collection
|
|
query(Order).options(
|
|
lazyload(Order.items).joinedload(Item.keywords))
|
|
|
|
:param innerjoin: if ``True``, indicates that the joined eager load should
|
|
use an inner join instead of the default of left outer join::
|
|
|
|
query(Order).options(joinedload(Order.user, innerjoin=True))
|
|
|
|
In order to chain multiple eager joins together where some may be
|
|
OUTER and others INNER, right-nested joins are used to link them::
|
|
|
|
query(A).options(
|
|
joinedload(A.bs, innerjoin=False).
|
|
joinedload(B.cs, innerjoin=True)
|
|
)
|
|
|
|
The above query, linking A.bs via "outer" join and B.cs via "inner" join
|
|
would render the joins as "a LEFT OUTER JOIN (b JOIN c)". When using
|
|
older versions of SQLite (< 3.7.16), this form of JOIN is translated to
|
|
use full subqueries as this syntax is otherwise not directly supported.
|
|
|
|
The ``innerjoin`` flag can also be stated with the term ``"unnested"``.
|
|
This indicates that an INNER JOIN should be used, *unless* the join
|
|
is linked to a LEFT OUTER JOIN to the left, in which case it
|
|
will render as LEFT OUTER JOIN. For example, supposing ``A.bs``
|
|
is an outerjoin::
|
|
|
|
query(A).options(
|
|
joinedload(A.bs).
|
|
joinedload(B.cs, innerjoin="unnested")
|
|
)
|
|
|
|
The above join will render as "a LEFT OUTER JOIN b LEFT OUTER JOIN c",
|
|
rather than as "a LEFT OUTER JOIN (b JOIN c)".
|
|
|
|
.. note:: The "unnested" flag does **not** affect the JOIN rendered
|
|
from a many-to-many association table, e.g. a table configured
|
|
as :paramref:`.relationship.secondary`, to the target table; for
|
|
correctness of results, these joins are always INNER and are
|
|
therefore right-nested if linked to an OUTER join.
|
|
|
|
.. versionchanged:: 1.0.0 ``innerjoin=True`` now implies
|
|
``innerjoin="nested"``, whereas in 0.9 it implied
|
|
``innerjoin="unnested"``. In order to achieve the pre-1.0 "unnested"
|
|
inner join behavior, use the value ``innerjoin="unnested"``.
|
|
See :ref:`migration_3008`.
|
|
|
|
.. note::
|
|
|
|
The joins produced by :func:`.orm.joinedload` are **anonymously
|
|
aliased**. The criteria by which the join proceeds cannot be
|
|
modified, nor can the :class:`.Query` refer to these joins in any way,
|
|
including ordering. See :ref:`zen_of_eager_loading` for further
|
|
detail.
|
|
|
|
To produce a specific SQL JOIN which is explicitly available, use
|
|
:meth:`.Query.join`. To combine explicit JOINs with eager loading
|
|
of collections, use :func:`.orm.contains_eager`; see
|
|
:ref:`contains_eager`.
|
|
|
|
.. seealso::
|
|
|
|
:ref:`loading_toplevel`
|
|
|
|
:ref:`joined_eager_loading`
|
|
|
|
"""
|
|
loader = loadopt.set_relationship_strategy(attr, {"lazy": "joined"})
|
|
if innerjoin is not None:
|
|
loader.local_opts["innerjoin"] = innerjoin
|
|
return loader
|
|
|
|
|
|
@joinedload._add_unbound_fn
|
|
def joinedload(*keys, **kw):
|
|
return _UnboundLoad._from_keys(_UnboundLoad.joinedload, keys, False, kw)
|
|
|
|
|
|
@joinedload._add_unbound_all_fn
|
|
def joinedload_all(*keys, **kw):
|
|
return _UnboundLoad._from_keys(_UnboundLoad.joinedload, keys, True, kw)
|
|
|
|
|
|
@loader_option()
|
|
def subqueryload(loadopt, attr):
|
|
"""Indicate that the given attribute should be loaded using
|
|
subquery eager loading.
|
|
|
|
This function is part of the :class:`.Load` interface and supports
|
|
both method-chained and standalone operation.
|
|
|
|
examples::
|
|
|
|
# subquery-load the "orders" collection on "User"
|
|
query(User).options(subqueryload(User.orders))
|
|
|
|
# subquery-load Order.items and then Item.keywords
|
|
query(Order).options(
|
|
subqueryload(Order.items).subqueryload(Item.keywords))
|
|
|
|
# lazily load Order.items, but when Items are loaded,
|
|
# subquery-load the keywords collection
|
|
query(Order).options(
|
|
lazyload(Order.items).subqueryload(Item.keywords))
|
|
|
|
|
|
.. seealso::
|
|
|
|
:ref:`loading_toplevel`
|
|
|
|
:ref:`subquery_eager_loading`
|
|
|
|
"""
|
|
return loadopt.set_relationship_strategy(attr, {"lazy": "subquery"})
|
|
|
|
|
|
@subqueryload._add_unbound_fn
|
|
def subqueryload(*keys):
|
|
return _UnboundLoad._from_keys(_UnboundLoad.subqueryload, keys, False, {})
|
|
|
|
|
|
@subqueryload._add_unbound_all_fn
|
|
def subqueryload_all(*keys):
|
|
return _UnboundLoad._from_keys(_UnboundLoad.subqueryload, keys, True, {})
|
|
|
|
|
|
@loader_option()
|
|
def selectinload(loadopt, attr):
|
|
"""Indicate that the given attribute should be loaded using
|
|
SELECT IN eager loading.
|
|
|
|
This function is part of the :class:`.Load` interface and supports
|
|
both method-chained and standalone operation.
|
|
|
|
examples::
|
|
|
|
# selectin-load the "orders" collection on "User"
|
|
query(User).options(selectinload(User.orders))
|
|
|
|
# selectin-load Order.items and then Item.keywords
|
|
query(Order).options(
|
|
selectinload(Order.items).selectinload(Item.keywords))
|
|
|
|
# lazily load Order.items, but when Items are loaded,
|
|
# selectin-load the keywords collection
|
|
query(Order).options(
|
|
lazyload(Order.items).selectinload(Item.keywords))
|
|
|
|
.. versionadded:: 1.2
|
|
|
|
.. seealso::
|
|
|
|
:ref:`loading_toplevel`
|
|
|
|
:ref:`selectin_eager_loading`
|
|
|
|
"""
|
|
return loadopt.set_relationship_strategy(attr, {"lazy": "selectin"})
|
|
|
|
|
|
@selectinload._add_unbound_fn
|
|
def selectinload(*keys):
|
|
return _UnboundLoad._from_keys(_UnboundLoad.selectinload, keys, False, {})
|
|
|
|
|
|
@selectinload._add_unbound_all_fn
|
|
def selectinload_all(*keys):
|
|
return _UnboundLoad._from_keys(_UnboundLoad.selectinload, keys, True, {})
|
|
|
|
|
|
@loader_option()
|
|
def lazyload(loadopt, attr):
|
|
"""Indicate that the given attribute should be loaded using "lazy"
|
|
loading.
|
|
|
|
This function is part of the :class:`.Load` interface and supports
|
|
both method-chained and standalone operation.
|
|
|
|
.. seealso::
|
|
|
|
:ref:`loading_toplevel`
|
|
|
|
:ref:`lazy_loading`
|
|
|
|
"""
|
|
return loadopt.set_relationship_strategy(attr, {"lazy": "select"})
|
|
|
|
|
|
@lazyload._add_unbound_fn
|
|
def lazyload(*keys):
|
|
return _UnboundLoad._from_keys(_UnboundLoad.lazyload, keys, False, {})
|
|
|
|
|
|
@lazyload._add_unbound_all_fn
|
|
def lazyload_all(*keys):
|
|
return _UnboundLoad._from_keys(_UnboundLoad.lazyload, keys, True, {})
|
|
|
|
|
|
@loader_option()
|
|
def immediateload(loadopt, attr):
|
|
"""Indicate that the given attribute should be loaded using
|
|
an immediate load with a per-attribute SELECT statement.
|
|
|
|
The :func:`.immediateload` option is superseded in general
|
|
by the :func:`.selectinload` option, which performs the same task
|
|
more efficiently by emitting a SELECT for all loaded objects.
|
|
|
|
This function is part of the :class:`.Load` interface and supports
|
|
both method-chained and standalone operation.
|
|
|
|
.. seealso::
|
|
|
|
:ref:`loading_toplevel`
|
|
|
|
:ref:`selectin_eager_loading`
|
|
|
|
"""
|
|
loader = loadopt.set_relationship_strategy(attr, {"lazy": "immediate"})
|
|
return loader
|
|
|
|
|
|
@immediateload._add_unbound_fn
|
|
def immediateload(*keys):
|
|
return _UnboundLoad._from_keys(_UnboundLoad.immediateload, keys, False, {})
|
|
|
|
|
|
@loader_option()
|
|
def noload(loadopt, attr):
|
|
"""Indicate that the given relationship attribute should remain unloaded.
|
|
|
|
This function is part of the :class:`.Load` interface and supports
|
|
both method-chained and standalone operation.
|
|
|
|
:func:`.orm.noload` applies to :func:`.relationship` attributes; for
|
|
column-based attributes, see :func:`.orm.defer`.
|
|
|
|
.. seealso::
|
|
|
|
:ref:`loading_toplevel`
|
|
|
|
"""
|
|
|
|
return loadopt.set_relationship_strategy(attr, {"lazy": "noload"})
|
|
|
|
|
|
@noload._add_unbound_fn
|
|
def noload(*keys):
|
|
return _UnboundLoad._from_keys(_UnboundLoad.noload, keys, False, {})
|
|
|
|
|
|
@loader_option()
|
|
def raiseload(loadopt, attr, sql_only=False):
|
|
"""Indicate that the given relationship attribute should disallow lazy loads.
|
|
|
|
A relationship attribute configured with :func:`.orm.raiseload` will
|
|
raise an :exc:`~sqlalchemy.exc.InvalidRequestError` upon access. The
|
|
typical way this is useful is when an application is attempting to ensure
|
|
that all relationship attributes that are accessed in a particular context
|
|
would have been already loaded via eager loading. Instead of having
|
|
to read through SQL logs to ensure lazy loads aren't occurring, this
|
|
strategy will cause them to raise immediately.
|
|
|
|
:param sql_only: if True, raise only if the lazy load would emit SQL,
|
|
but not if it is only checking the identity map, or determining that
|
|
the related value should just be None due to missing keys. When False,
|
|
the strategy will raise for all varieties of lazyload.
|
|
|
|
This function is part of the :class:`.Load` interface and supports
|
|
both method-chained and standalone operation.
|
|
|
|
:func:`.orm.raiseload` applies to :func:`.relationship` attributes only.
|
|
|
|
.. versionadded:: 1.1
|
|
|
|
.. seealso::
|
|
|
|
:ref:`loading_toplevel`
|
|
|
|
:ref:`prevent_lazy_with_raiseload`
|
|
|
|
"""
|
|
|
|
return loadopt.set_relationship_strategy(
|
|
attr, {"lazy": "raise_on_sql" if sql_only else "raise"}
|
|
)
|
|
|
|
|
|
@raiseload._add_unbound_fn
|
|
def raiseload(*keys, **kw):
|
|
return _UnboundLoad._from_keys(_UnboundLoad.raiseload, keys, False, kw)
|
|
|
|
|
|
@loader_option()
|
|
def defaultload(loadopt, attr):
|
|
"""Indicate an attribute should load using its default loader style.
|
|
|
|
This method is used to link to other loader options further into
|
|
a chain of attributes without altering the loader style of the links
|
|
along the chain. For example, to set joined eager loading for an
|
|
element of an element::
|
|
|
|
session.query(MyClass).options(
|
|
defaultload(MyClass.someattribute).
|
|
joinedload(MyOtherClass.someotherattribute)
|
|
)
|
|
|
|
:func:`.defaultload` is also useful for setting column-level options
|
|
on a related class, namely that of :func:`.defer` and :func:`.undefer`::
|
|
|
|
session.query(MyClass).options(
|
|
defaultload(MyClass.someattribute).
|
|
defer("some_column").
|
|
undefer("some_other_column")
|
|
)
|
|
|
|
.. seealso::
|
|
|
|
:meth:`.Load.options` - allows for complex hierarchical
|
|
loader option structures with less verbosity than with individual
|
|
:func:`.defaultload` directives.
|
|
|
|
:ref:`relationship_loader_options`
|
|
|
|
:ref:`deferred_loading_w_multiple`
|
|
|
|
"""
|
|
return loadopt.set_relationship_strategy(attr, None)
|
|
|
|
|
|
@defaultload._add_unbound_fn
|
|
def defaultload(*keys):
|
|
return _UnboundLoad._from_keys(_UnboundLoad.defaultload, keys, False, {})
|
|
|
|
|
|
@loader_option()
|
|
def defer(loadopt, key):
|
|
r"""Indicate that the given column-oriented attribute should be deferred,
|
|
e.g. not loaded until accessed.
|
|
|
|
This function is part of the :class:`.Load` interface and supports
|
|
both method-chained and standalone operation.
|
|
|
|
e.g.::
|
|
|
|
from sqlalchemy.orm import defer
|
|
|
|
session.query(MyClass).options(
|
|
defer("attribute_one"),
|
|
defer("attribute_two"))
|
|
|
|
session.query(MyClass).options(
|
|
defer(MyClass.attribute_one),
|
|
defer(MyClass.attribute_two))
|
|
|
|
To specify a deferred load of an attribute on a related class,
|
|
the path can be specified one token at a time, specifying the loading
|
|
style for each link along the chain. To leave the loading style
|
|
for a link unchanged, use :func:`.orm.defaultload`::
|
|
|
|
session.query(MyClass).options(defaultload("someattr").defer("some_column"))
|
|
|
|
A :class:`.Load` object that is present on a certain path can have
|
|
:meth:`.Load.defer` called multiple times, each will operate on the same
|
|
parent entity::
|
|
|
|
|
|
session.query(MyClass).options(
|
|
defaultload("someattr").
|
|
defer("some_column").
|
|
defer("some_other_column").
|
|
defer("another_column")
|
|
)
|
|
|
|
:param key: Attribute to be deferred.
|
|
|
|
:param \*addl_attrs: This option supports the old 0.8 style
|
|
of specifying a path as a series of attributes, which is now superseded
|
|
by the method-chained style.
|
|
|
|
.. deprecated:: 0.9 The \*addl_attrs on :func:`.orm.defer` is
|
|
deprecated and will be removed in a future release. Please
|
|
use method chaining in conjunction with defaultload() to
|
|
indicate a path.
|
|
|
|
|
|
.. seealso::
|
|
|
|
:ref:`deferred`
|
|
|
|
:func:`.orm.undefer`
|
|
|
|
"""
|
|
return loadopt.set_column_strategy(
|
|
(key,), {"deferred": True, "instrument": True}
|
|
)
|
|
|
|
|
|
@defer._add_unbound_fn
|
|
def defer(key, *addl_attrs):
|
|
if addl_attrs:
|
|
util.warn_deprecated(
|
|
"The *addl_attrs on orm.defer is deprecated. Please use "
|
|
"method chaining in conjunction with defaultload() to "
|
|
"indicate a path."
|
|
)
|
|
return _UnboundLoad._from_keys(
|
|
_UnboundLoad.defer, (key,) + addl_attrs, False, {}
|
|
)
|
|
|
|
|
|
@loader_option()
|
|
def undefer(loadopt, key):
|
|
r"""Indicate that the given column-oriented attribute should be undeferred,
|
|
e.g. specified within the SELECT statement of the entity as a whole.
|
|
|
|
The column being undeferred is typically set up on the mapping as a
|
|
:func:`.deferred` attribute.
|
|
|
|
This function is part of the :class:`.Load` interface and supports
|
|
both method-chained and standalone operation.
|
|
|
|
Examples::
|
|
|
|
# undefer two columns
|
|
session.query(MyClass).options(undefer("col1"), undefer("col2"))
|
|
|
|
# undefer all columns specific to a single class using Load + *
|
|
session.query(MyClass, MyOtherClass).options(
|
|
Load(MyClass).undefer("*"))
|
|
|
|
# undefer a column on a related object
|
|
session.query(MyClass).options(
|
|
defaultload(MyClass.items).undefer('text'))
|
|
|
|
:param key: Attribute to be undeferred.
|
|
|
|
:param \*addl_attrs: This option supports the old 0.8 style
|
|
of specifying a path as a series of attributes, which is now superseded
|
|
by the method-chained style.
|
|
|
|
.. deprecated:: 0.9 The \*addl_attrs on :func:`.orm.undefer` is
|
|
deprecated and will be removed in a future release. Please
|
|
use method chaining in conjunction with defaultload() to
|
|
indicate a path.
|
|
|
|
.. seealso::
|
|
|
|
:ref:`deferred`
|
|
|
|
:func:`.orm.defer`
|
|
|
|
:func:`.orm.undefer_group`
|
|
|
|
"""
|
|
return loadopt.set_column_strategy(
|
|
(key,), {"deferred": False, "instrument": True}
|
|
)
|
|
|
|
|
|
@undefer._add_unbound_fn
|
|
def undefer(key, *addl_attrs):
|
|
if addl_attrs:
|
|
util.warn_deprecated(
|
|
"The *addl_attrs on orm.undefer is deprecated. Please use "
|
|
"method chaining in conjunction with defaultload() to "
|
|
"indicate a path."
|
|
)
|
|
return _UnboundLoad._from_keys(
|
|
_UnboundLoad.undefer, (key,) + addl_attrs, False, {}
|
|
)
|
|
|
|
|
|
@loader_option()
|
|
def undefer_group(loadopt, name):
|
|
"""Indicate that columns within the given deferred group name should be
|
|
undeferred.
|
|
|
|
The columns being undeferred are set up on the mapping as
|
|
:func:`.deferred` attributes and include a "group" name.
|
|
|
|
E.g::
|
|
|
|
session.query(MyClass).options(undefer_group("large_attrs"))
|
|
|
|
To undefer a group of attributes on a related entity, the path can be
|
|
spelled out using relationship loader options, such as
|
|
:func:`.orm.defaultload`::
|
|
|
|
session.query(MyClass).options(
|
|
defaultload("someattr").undefer_group("large_attrs"))
|
|
|
|
.. versionchanged:: 0.9.0 :func:`.orm.undefer_group` is now specific to a
|
|
particular entity load path.
|
|
|
|
.. seealso::
|
|
|
|
:ref:`deferred`
|
|
|
|
:func:`.orm.defer`
|
|
|
|
:func:`.orm.undefer`
|
|
|
|
"""
|
|
return loadopt.set_column_strategy(
|
|
"*", None, {"undefer_group_%s" % name: True}, opts_only=True
|
|
)
|
|
|
|
|
|
@undefer_group._add_unbound_fn
|
|
def undefer_group(name):
|
|
return _UnboundLoad().undefer_group(name)
|
|
|
|
|
|
@loader_option()
|
|
def with_expression(loadopt, key, expression):
|
|
r"""Apply an ad-hoc SQL expression to a "deferred expression" attribute.
|
|
|
|
This option is used in conjunction with the :func:`.orm.query_expression`
|
|
mapper-level construct that indicates an attribute which should be the
|
|
target of an ad-hoc SQL expression.
|
|
|
|
E.g.::
|
|
|
|
|
|
sess.query(SomeClass).options(
|
|
with_expression(SomeClass.x_y_expr, SomeClass.x + SomeClass.y)
|
|
)
|
|
|
|
.. versionadded:: 1.2
|
|
|
|
:param key: Attribute to be undeferred.
|
|
|
|
:param expr: SQL expression to be applied to the attribute.
|
|
|
|
.. seealso::
|
|
|
|
:ref:`mapper_query_expression`
|
|
|
|
"""
|
|
|
|
expression = sql_expr._labeled(_orm_full_deannotate(expression))
|
|
|
|
return loadopt.set_column_strategy(
|
|
(key,), {"query_expression": True}, opts={"expression": expression}
|
|
)
|
|
|
|
|
|
@with_expression._add_unbound_fn
|
|
def with_expression(key, expression):
|
|
return _UnboundLoad._from_keys(
|
|
_UnboundLoad.with_expression, (key,), False, {"expression": expression}
|
|
)
|
|
|
|
|
|
@loader_option()
|
|
def selectin_polymorphic(loadopt, classes):
|
|
"""Indicate an eager load should take place for all attributes
|
|
specific to a subclass.
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|
|
|
This uses an additional SELECT with IN against all matched primary
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|
key values, and is the per-query analogue to the ``"selectin"``
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|
setting on the :paramref:`.mapper.polymorphic_load` parameter.
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|
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.. versionadded:: 1.2
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|
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.. seealso::
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|
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|
:ref:`inheritance_polymorphic_load`
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|
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|
"""
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|
loadopt.set_class_strategy(
|
|
{"selectinload_polymorphic": True},
|
|
opts={
|
|
"entities": tuple(
|
|
sorted((inspect(cls) for cls in classes), key=id)
|
|
)
|
|
},
|
|
)
|
|
return loadopt
|
|
|
|
|
|
@selectin_polymorphic._add_unbound_fn
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|
def selectin_polymorphic(base_cls, classes):
|
|
ul = _UnboundLoad()
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|
ul.is_class_strategy = True
|
|
ul.path = (inspect(base_cls),)
|
|
ul.selectin_polymorphic(classes)
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|
return ul
|