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path_registry.py
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# orm/path_registry.py # Copyright (C) 2005-2024 the SQLAlchemy authors and contributors # <see AUTHORS file> # # This module is part of SQLAlchemy and is released under # the MIT License: https://www.opensource.org/licenses/mit-license.php """Path tracking utilities, representing mapper graph traversals. """ from __future__ import annotations from functools import reduce from itertools import chain import logging import operator from typing import Any from typing import cast from typing import Dict from typing import Iterator from typing import List from typing import Optional from typing import overload from typing import Sequence from typing import Tuple from typing import TYPE_CHECKING from typing import Union from . import base as orm_base from ._typing import insp_is_mapper_property from .. import exc from .. import util from ..sql import visitors from ..sql.cache_key import HasCacheKey if TYPE_CHECKING: from ._typing import _InternalEntityType from .interfaces import StrategizedProperty from .mapper import Mapper from .relationships import RelationshipProperty from .util import AliasedInsp from ..sql.cache_key import _CacheKeyTraversalType from ..sql.elements import BindParameter from ..sql.visitors import anon_map from ..util.typing import _LiteralStar from ..util.typing import TypeGuard def is_root(path: PathRegistry) -> TypeGuard[RootRegistry]: ... def is_entity(path: PathRegistry) -> TypeGuard[AbstractEntityRegistry]: ... else: is_root = operator.attrgetter("is_root") is_entity = operator.attrgetter("is_entity") _SerializedPath = List[Any] _StrPathToken = str _PathElementType = Union[ _StrPathToken, "_InternalEntityType[Any]", "StrategizedProperty[Any]" ] # the representation is in fact # a tuple with alternating: # [_InternalEntityType[Any], Union[str, StrategizedProperty[Any]], # _InternalEntityType[Any], Union[str, StrategizedProperty[Any]], ...] # this might someday be a tuple of 2-tuples instead, but paths can be # chopped at odd intervals as well so this is less flexible _PathRepresentation = Tuple[_PathElementType, ...] # NOTE: these names are weird since the array is 0-indexed, # the "_Odd" entries are at 0, 2, 4, etc _OddPathRepresentation = Sequence["_InternalEntityType[Any]"] _EvenPathRepresentation = Sequence[Union["StrategizedProperty[Any]", str]] log = logging.getLogger(__name__) def _unreduce_path(path: _SerializedPath) -> PathRegistry: return PathRegistry.deserialize(path) _WILDCARD_TOKEN: _LiteralStar = "*" _DEFAULT_TOKEN = "_sa_default" class PathRegistry(HasCacheKey): """Represent query load paths and registry functions. Basically represents structures like: (<User mapper>, "orders", <Order mapper>, "items", <Item mapper>) These structures are generated by things like query options (joinedload(), subqueryload(), etc.) and are used to compose keys stored in the query._attributes dictionary for various options. They are then re-composed at query compile/result row time as the query is formed and as rows are fetched, where they again serve to compose keys to look up options in the context.attributes dictionary, which is copied from query._attributes. The path structure has a limited amount of caching, where each "root" ultimately pulls from a fixed registry associated with the first mapper, that also contains elements for each of its property keys. However paths longer than two elements, which are the exception rather than the rule, are generated on an as-needed basis. """ __slots__ = () is_token = False is_root = False has_entity = False is_property = False is_entity = False is_unnatural: bool path: _PathRepresentation natural_path: _PathRepresentation parent: Optional[PathRegistry] root: RootRegistry _cache_key_traversal: _CacheKeyTraversalType = [ ("path", visitors.ExtendedInternalTraversal.dp_has_cache_key_list) ] def __eq__(self, other: Any) -> bool: try: return other is not None and self.path == other._path_for_compare except AttributeError: util.warn( "Comparison of PathRegistry to %r is not supported" % (type(other)) ) return False def __ne__(self, other: Any) -> bool: try: return other is None or self.path != other._path_for_compare except AttributeError: util.warn( "Comparison of PathRegistry to %r is not supported" % (type(other)) ) return True @property def _path_for_compare(self) -> Optional[_PathRepresentation]: return self.path def odd_element(self, index: int) -> _InternalEntityType[Any]: return self.path[index] # type: ignore def set(self, attributes: Dict[Any, Any], key: Any, value: Any) -> None: log.debug("set '%s' on path '%s' to '%s'", key, self, value) attributes[(key, self.natural_path)] = value def setdefault( self, attributes: Dict[Any, Any], key: Any, value: Any ) -> None: log.debug("setdefault '%s' on path '%s' to '%s'", key, self, value) attributes.setdefault((key, self.natural_path), value) def get( self, attributes: Dict[Any, Any], key: Any, value: Optional[Any] = None ) -> Any: key = (key, self.natural_path) if key in attributes: return attributes[key] else: return value def __len__(self) -> int: return len(self.path) def __hash__(self) -> int: return id(self) @overload def __getitem__(self, entity: _StrPathToken) -> TokenRegistry: ... @overload def __getitem__(self, entity: int) -> _PathElementType: ... @overload def __getitem__(self, entity: slice) -> _PathRepresentation: ... @overload def __getitem__( self, entity: _InternalEntityType[Any] ) -> AbstractEntityRegistry: ... @overload def __getitem__( self, entity: StrategizedProperty[Any] ) -> PropRegistry: ... def __getitem__( self, entity: Union[ _StrPathToken, int, slice, _InternalEntityType[Any], StrategizedProperty[Any], ], ) -> Union[ TokenRegistry, _PathElementType, _PathRepresentation, PropRegistry, AbstractEntityRegistry, ]: raise NotImplementedError() # TODO: what are we using this for? @property def length(self) -> int: return len(self.path) def pairs( self, ) -> Iterator[ Tuple[_InternalEntityType[Any], Union[str, StrategizedProperty[Any]]] ]: odd_path = cast(_OddPathRepresentation, self.path) even_path = cast(_EvenPathRepresentation, odd_path) for i in range(0, len(odd_path), 2): yield odd_path[i], even_path[i + 1] def contains_mapper(self, mapper: Mapper[Any]) -> bool: _m_path = cast(_OddPathRepresentation, self.path) for path_mapper in [_m_path[i] for i in range(0, len(_m_path), 2)]: if path_mapper.mapper.isa(mapper): return True else: return False def contains(self, attributes: Dict[Any, Any], key: Any) -> bool: return (key, self.path) in attributes def __reduce__(self) -> Any: return _unreduce_path, (self.serialize(),) @classmethod def _serialize_path(cls, path: _PathRepresentation) -> _SerializedPath: _m_path = cast(_OddPathRepresentation, path) _p_path = cast(_EvenPathRepresentation, path) return list( zip( tuple( m.class_ if (m.is_mapper or m.is_aliased_class) else str(m) for m in [_m_path[i] for i in range(0, len(_m_path), 2)] ), tuple( p.key if insp_is_mapper_property(p) else str(p) for p in [_p_path[i] for i in range(1, len(_p_path), 2)] ) + (None,), ) ) @classmethod def _deserialize_path(cls, path: _SerializedPath) -> _PathRepresentation: def _deserialize_mapper_token(mcls: Any) -> Any: return ( # note: we likely dont want configure=True here however # this is maintained at the moment for backwards compatibility orm_base._inspect_mapped_class(mcls, configure=True) if mcls not in PathToken._intern else PathToken._intern[mcls] ) def _deserialize_key_token(mcls: Any, key: Any) -> Any: if key is None: return None elif key in PathToken._intern: return PathToken._intern[key] else: mp = orm_base._inspect_mapped_class(mcls, configure=True) assert mp is not None return mp.attrs[key] p = tuple( chain( *[ ( _deserialize_mapper_token(mcls), _deserialize_key_token(mcls, key), ) for mcls, key in path ] ) ) if p and p[-1] is None: p = p[0:-1] return p def serialize(self) -> _SerializedPath: path = self.path return self._serialize_path(path) @classmethod def deserialize(cls, path: _SerializedPath) -> PathRegistry: assert path is not None p = cls._deserialize_path(path) return cls.coerce(p) @overload @classmethod def per_mapper(cls, mapper: Mapper[Any]) -> CachingEntityRegistry: ... @overload @classmethod def per_mapper(cls, mapper: AliasedInsp[Any]) -> SlotsEntityRegistry: ... @classmethod def per_mapper( cls, mapper: _InternalEntityType[Any] ) -> AbstractEntityRegistry: if mapper.is_mapper: return CachingEntityRegistry(cls.root, mapper) else: return SlotsEntityRegistry(cls.root, mapper) @classmethod def coerce(cls, raw: _PathRepresentation) -> PathRegistry: def _red(prev: PathRegistry, next_: _PathElementType) -> PathRegistry: return prev[next_] # can't quite get mypy to appreciate this one :) return reduce(_red, raw, cls.root) # type: ignore def __add__(self, other: PathRegistry) -> PathRegistry: def _red(prev: PathRegistry, next_: _PathElementType) -> PathRegistry: return prev[next_] return reduce(_red, other.path, self) def __str__(self) -> str: return f"ORM Path[{' -> '.join(str(elem) for elem in self.path)}]" def __repr__(self) -> str: return f"{self.__class__.__name__}({self.path!r})" class CreatesToken(PathRegistry): __slots__ = () is_aliased_class: bool is_root: bool def token(self, token: _StrPathToken) -> TokenRegistry: if token.endswith(f":{_WILDCARD_TOKEN}"): return TokenRegistry(self, token) elif token.endswith(f":{_DEFAULT_TOKEN}"): return TokenRegistry(self.root, token) else: raise exc.ArgumentError(f"invalid token: {token}") class RootRegistry(CreatesToken): """Root registry, defers to mappers so that paths are maintained per-root-mapper. """ __slots__ = () inherit_cache = True path = natural_path = () has_entity = False is_aliased_class = False is_root = True is_unnatural = False def _getitem( self, entity: Any ) -> Union[TokenRegistry, AbstractEntityRegistry]: if entity in PathToken._intern: if TYPE_CHECKING: assert isinstance(entity, _StrPathToken) return TokenRegistry(self, PathToken._intern[entity]) else: try: return entity._path_registry # type: ignore except AttributeError: raise IndexError( f"invalid argument for RootRegistry.__getitem__: {entity}" ) def _truncate_recursive(self) -> RootRegistry: return self if not TYPE_CHECKING: __getitem__ = _getitem PathRegistry.root = RootRegistry() class PathToken(orm_base.InspectionAttr, HasCacheKey, str): """cacheable string token""" _intern: Dict[str, PathToken] = {} def _gen_cache_key( self, anon_map: anon_map, bindparams: List[BindParameter[Any]] ) -> Tuple[Any, ...]: return (str(self),) @property def _path_for_compare(self) -> Optional[_PathRepresentation]: return None @classmethod def intern(cls, strvalue: str) -> PathToken: if strvalue in cls._intern: return cls._intern[strvalue] else: cls._intern[strvalue] = result = PathToken(strvalue) return result class TokenRegistry(PathRegistry): __slots__ = ("token", "parent", "path", "natural_path") inherit_cache = True token: _StrPathToken parent: CreatesToken def __init__(self, parent: CreatesToken, token: _StrPathToken): token = PathToken.intern(token) self.token = token self.parent = parent self.path = parent.path + (token,) self.natural_path = parent.natural_path + (token,) has_entity = False is_token = True def generate_for_superclasses(self) -> Iterator[PathRegistry]: # NOTE: this method is no longer used. consider removal parent = self.parent if is_root(parent): yield self return if TYPE_CHECKING: assert isinstance(parent, AbstractEntityRegistry) if not parent.is_aliased_class: for mp_ent in parent.mapper.iterate_to_root(): yield TokenRegistry(parent.parent[mp_ent], self.token) elif ( parent.is_aliased_class and cast( "AliasedInsp[Any]", parent.entity, )._is_with_polymorphic ): yield self for ent in cast( "AliasedInsp[Any]", parent.entity )._with_polymorphic_entities: yield TokenRegistry(parent.parent[ent], self.token) else: yield self def _generate_natural_for_superclasses( self, ) -> Iterator[_PathRepresentation]: parent = self.parent if is_root(parent): yield self.natural_path return if TYPE_CHECKING: assert isinstance(parent, AbstractEntityRegistry) for mp_ent in parent.mapper.iterate_to_root(): yield TokenRegistry(parent.parent[mp_ent], self.token).natural_path if ( parent.is_aliased_class and cast( "AliasedInsp[Any]", parent.entity, )._is_with_polymorphic ): yield self.natural_path for ent in cast( "AliasedInsp[Any]", parent.entity )._with_polymorphic_entities: yield ( TokenRegistry(parent.parent[ent], self.token).natural_path ) else: yield self.natural_path def _getitem(self, entity: Any) -> Any: try: return self.path[entity] except TypeError as err: raise IndexError(f"{entity}") from err if not TYPE_CHECKING: __getitem__ = _getitem class PropRegistry(PathRegistry): __slots__ = ( "prop", "parent", "path", "natural_path", "has_entity", "entity", "mapper", "_wildcard_path_loader_key", "_default_path_loader_key", "_loader_key", "is_unnatural", ) inherit_cache = True is_property = True prop: StrategizedProperty[Any] mapper: Optional[Mapper[Any]] entity: Optional[_InternalEntityType[Any]] def __init__( self, parent: AbstractEntityRegistry, prop: StrategizedProperty[Any] ): # restate this path in terms of the # given StrategizedProperty's parent. insp = cast("_InternalEntityType[Any]", parent[-1]) natural_parent: AbstractEntityRegistry = parent # inherit "is_unnatural" from the parent self.is_unnatural = parent.parent.is_unnatural or bool( parent.mapper.inherits ) if not insp.is_aliased_class or insp._use_mapper_path: # type: ignore parent = natural_parent = parent.parent[prop.parent] elif ( insp.is_aliased_class and insp.with_polymorphic_mappers and prop.parent in insp.with_polymorphic_mappers ): subclass_entity: _InternalEntityType[Any] = parent[-1]._entity_for_mapper(prop.parent) # type: ignore # noqa: E501 parent = parent.parent[subclass_entity] # when building a path where with_polymorphic() is in use, # special logic to determine the "natural path" when subclass # entities are used. # # here we are trying to distinguish between a path that starts # on a the with_polymorhpic entity vs. one that starts on a # normal entity that introduces a with_polymorphic() in the # middle using of_type(): # # # as in test_polymorphic_rel-> # # test_subqueryload_on_subclass_uses_path_correctly # wp = with_polymorphic(RegularEntity, "*") # sess.query(wp).options(someload(wp.SomeSubEntity.foos)) # # vs # # # as in test_relationship->JoinedloadWPolyOfTypeContinued # wp = with_polymorphic(SomeFoo, "*") # sess.query(RegularEntity).options( # someload(RegularEntity.foos.of_type(wp)) # .someload(wp.SubFoo.bar) # ) # # in the former case, the Query as it generates a path that we # want to match will be in terms of the with_polymorphic at the # beginning. in the latter case, Query will generate simple # paths that don't know about this with_polymorphic, so we must # use a separate natural path. # # if parent.parent: natural_parent = parent.parent[subclass_entity.mapper] self.is_unnatural = True else: natural_parent = parent elif ( natural_parent.parent and insp.is_aliased_class and prop.parent # this should always be the case here is not insp.mapper and insp.mapper.isa(prop.parent) ): natural_parent = parent.parent[prop.parent] self.prop = prop self.parent = parent self.path = parent.path + (prop,) self.natural_path = natural_parent.natural_path + (prop,) self.has_entity = prop._links_to_entity if prop._is_relationship: if TYPE_CHECKING: assert isinstance(prop, RelationshipProperty) self.entity = prop.entity self.mapper = prop.mapper else: self.entity = None self.mapper = None self._wildcard_path_loader_key = ( "loader", parent.natural_path + self.prop._wildcard_token, ) self._default_path_loader_key = self.prop._default_path_loader_key self._loader_key = ("loader", self.natural_path) def _truncate_recursive(self) -> PropRegistry: earliest = None for i, token in enumerate(reversed(self.path[:-1])): if token is self.prop: earliest = i if earliest is None: return self else: return self.coerce(self.path[0 : -(earliest + 1)]) # type: ignore @property def entity_path(self) -> AbstractEntityRegistry: assert self.entity is not None return self[self.entity] def _getitem( self, entity: Union[int, slice, _InternalEntityType[Any]] ) -> Union[AbstractEntityRegistry, _PathElementType, _PathRepresentation]: if isinstance(entity, (int, slice)): return self.path[entity] else: return SlotsEntityRegistry(self, entity) if not TYPE_CHECKING: __getitem__ = _getitem class AbstractEntityRegistry(CreatesToken): __slots__ = ( "key", "parent", "is_aliased_class", "path", "entity", "natural_path", ) has_entity = True is_entity = True parent: Union[RootRegistry, PropRegistry] key: _InternalEntityType[Any] entity: _InternalEntityType[Any] is_aliased_class: bool def __init__( self, parent: Union[RootRegistry, PropRegistry], entity: _InternalEntityType[Any], ): self.key = entity self.parent = parent self.is_aliased_class = entity.is_aliased_class self.entity = entity self.path = parent.path + (entity,) # the "natural path" is the path that we get when Query is traversing # from the lead entities into the various relationships; it corresponds # to the structure of mappers and relationships. when we are given a # path that comes from loader options, as of 1.3 it can have ac-hoc # with_polymorphic() and other AliasedInsp objects inside of it, which # are usually not present in mappings. So here we track both the # "enhanced" path in self.path and the "natural" path that doesn't # include those objects so these two traversals can be matched up. # the test here for "(self.is_aliased_class or parent.is_unnatural)" # are to avoid the more expensive conditional logic that follows if we # know we don't have to do it. This conditional can just as well be # "if parent.path:", it just is more function calls. # # This is basically the only place that the "is_unnatural" flag # actually changes behavior. if parent.path and (self.is_aliased_class or parent.is_unnatural): # this is an infrequent code path used only for loader strategies # that also make use of of_type(). if entity.mapper.isa(parent.natural_path[-1].mapper): # type: ignore # noqa: E501 self.natural_path = parent.natural_path + (entity.mapper,) else: self.natural_path = parent.natural_path + ( parent.natural_path[-1].entity, # type: ignore ) # it seems to make sense that since these paths get mixed up # with statements that are cached or not, we should make # sure the natural path is cacheable across different occurrences # of equivalent AliasedClass objects. however, so far this # does not seem to be needed for whatever reason. # elif not parent.path and self.is_aliased_class: # self.natural_path = (self.entity._generate_cache_key()[0], ) else: self.natural_path = self.path def _truncate_recursive(self) -> AbstractEntityRegistry: return self.parent._truncate_recursive()[self.entity] @property def root_entity(self) -> _InternalEntityType[Any]: return self.odd_element(0) @property def entity_path(self) -> PathRegistry: return self @property def mapper(self) -> Mapper[Any]: return self.entity.mapper def __bool__(self) -> bool: return True def _getitem( self, entity: Any ) -> Union[_PathElementType, _PathRepresentation, PathRegistry]: if isinstance(entity, (int, slice)): return self.path[entity] elif entity in PathToken._intern: return TokenRegistry(self, PathToken._intern[entity]) else: return PropRegistry(self, entity) if not TYPE_CHECKING: __getitem__ = _getitem class SlotsEntityRegistry(AbstractEntityRegistry): # for aliased class, return lightweight, no-cycles created # version inherit_cache = True class _ERDict(Dict[Any, Any]): def __init__(self, registry: CachingEntityRegistry): self.registry = registry def __missing__(self, key: Any) -> PropRegistry: self[key] = item = PropRegistry(self.registry, key) return item class CachingEntityRegistry(AbstractEntityRegistry): # for long lived mapper, return dict based caching # version that creates reference cycles __slots__ = ("_cache",) inherit_cache = True def __init__( self, parent: Union[RootRegistry, PropRegistry], entity: _InternalEntityType[Any], ): super().__init__(parent, entity) self._cache = _ERDict(self) def pop(self, key: Any, default: Any) -> Any: return self._cache.pop(key, default) def _getitem(self, entity: Any) -> Any: if isinstance(entity, (int, slice)): return self.path[entity] elif isinstance(entity, PathToken): return TokenRegistry(self, entity) else: return self._cache[entity] if not TYPE_CHECKING: __getitem__ = _getitem if TYPE_CHECKING: def path_is_entity( path: PathRegistry, ) -> TypeGuard[AbstractEntityRegistry]: ... def path_is_property(path: PathRegistry) -> TypeGuard[PropRegistry]: ... else: path_is_entity = operator.attrgetter("is_entity") path_is_property = operator.attrgetter("is_property")