483 lines
15 KiB
Python
483 lines
15 KiB
Python
# orm/path_registry.py
|
|
# Copyright (C) 2005-2021 the SQLAlchemy authors and contributors
|
|
# <see AUTHORS file>
|
|
#
|
|
# This module is part of SQLAlchemy and is released under
|
|
# the MIT License: http://www.opensource.org/licenses/mit-license.php
|
|
"""Path tracking utilities, representing mapper graph traversals.
|
|
|
|
"""
|
|
|
|
from itertools import chain
|
|
import logging
|
|
|
|
from .base import class_mapper
|
|
from .. import exc
|
|
from .. import inspection
|
|
from .. import util
|
|
from ..sql import visitors
|
|
from ..sql.traversals import HasCacheKey
|
|
|
|
log = logging.getLogger(__name__)
|
|
|
|
|
|
def _unreduce_path(path):
|
|
return PathRegistry.deserialize(path)
|
|
|
|
|
|
_WILDCARD_TOKEN = "*"
|
|
_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
|
|
|
|
_cache_key_traversal = [
|
|
("path", visitors.ExtendedInternalTraversal.dp_has_cache_key_list)
|
|
]
|
|
|
|
def __eq__(self, other):
|
|
try:
|
|
return other is not None and self.path == other.path
|
|
except AttributeError:
|
|
util.warn(
|
|
"Comparison of PathRegistry to %r is not supported"
|
|
% (type(other))
|
|
)
|
|
return False
|
|
|
|
def __ne__(self, other):
|
|
try:
|
|
return other is None or self.path != other.path
|
|
except AttributeError:
|
|
util.warn(
|
|
"Comparison of PathRegistry to %r is not supported"
|
|
% (type(other))
|
|
)
|
|
return True
|
|
|
|
def set(self, attributes, key, value):
|
|
log.debug("set '%s' on path '%s' to '%s'", key, self, value)
|
|
attributes[(key, self.natural_path)] = value
|
|
|
|
def setdefault(self, attributes, key, value):
|
|
log.debug("setdefault '%s' on path '%s' to '%s'", key, self, value)
|
|
attributes.setdefault((key, self.natural_path), value)
|
|
|
|
def get(self, attributes, key, value=None):
|
|
key = (key, self.natural_path)
|
|
if key in attributes:
|
|
return attributes[key]
|
|
else:
|
|
return value
|
|
|
|
def __len__(self):
|
|
return len(self.path)
|
|
|
|
def __hash__(self):
|
|
return id(self)
|
|
|
|
@property
|
|
def length(self):
|
|
return len(self.path)
|
|
|
|
def pairs(self):
|
|
path = self.path
|
|
for i in range(0, len(path), 2):
|
|
yield path[i], path[i + 1]
|
|
|
|
def contains_mapper(self, mapper):
|
|
for path_mapper in [self.path[i] for i in range(0, len(self.path), 2)]:
|
|
if path_mapper.is_mapper and path_mapper.isa(mapper):
|
|
return True
|
|
else:
|
|
return False
|
|
|
|
def contains(self, attributes, key):
|
|
return (key, self.path) in attributes
|
|
|
|
def __reduce__(self):
|
|
return _unreduce_path, (self.serialize(),)
|
|
|
|
@classmethod
|
|
def _serialize_path(cls, path):
|
|
return list(
|
|
zip(
|
|
[m.class_ for m in [path[i] for i in range(0, len(path), 2)]],
|
|
[path[i].key for i in range(1, len(path), 2)] + [None],
|
|
)
|
|
)
|
|
|
|
@classmethod
|
|
def _deserialize_path(cls, path):
|
|
p = tuple(
|
|
chain(
|
|
*[
|
|
(
|
|
class_mapper(mcls),
|
|
class_mapper(mcls).attrs[key]
|
|
if key is not None
|
|
else None,
|
|
)
|
|
for mcls, key in path
|
|
]
|
|
)
|
|
)
|
|
if p and p[-1] is None:
|
|
p = p[0:-1]
|
|
return p
|
|
|
|
@classmethod
|
|
def serialize_context_dict(cls, dict_, tokens):
|
|
return [
|
|
((key, cls._serialize_path(path)), value)
|
|
for (key, path), value in [
|
|
(k, v)
|
|
for k, v in dict_.items()
|
|
if isinstance(k, tuple) and k[0] in tokens
|
|
]
|
|
]
|
|
|
|
@classmethod
|
|
def deserialize_context_dict(cls, serialized):
|
|
return util.OrderedDict(
|
|
((key, tuple(cls._deserialize_path(path))), value)
|
|
for (key, path), value in serialized
|
|
)
|
|
|
|
def serialize(self):
|
|
path = self.path
|
|
return self._serialize_path(path)
|
|
|
|
@classmethod
|
|
def deserialize(cls, path):
|
|
if path is None:
|
|
return None
|
|
p = cls._deserialize_path(path)
|
|
return cls.coerce(p)
|
|
|
|
@classmethod
|
|
def per_mapper(cls, mapper):
|
|
if mapper.is_mapper:
|
|
return CachingEntityRegistry(cls.root, mapper)
|
|
else:
|
|
return SlotsEntityRegistry(cls.root, mapper)
|
|
|
|
@classmethod
|
|
def coerce(cls, raw):
|
|
return util.reduce(lambda prev, next: prev[next], raw, cls.root)
|
|
|
|
def token(self, token):
|
|
if token.endswith(":" + _WILDCARD_TOKEN):
|
|
return TokenRegistry(self, token)
|
|
elif token.endswith(":" + _DEFAULT_TOKEN):
|
|
return TokenRegistry(self.root, token)
|
|
else:
|
|
raise exc.ArgumentError("invalid token: %s" % token)
|
|
|
|
def __add__(self, other):
|
|
return util.reduce(lambda prev, next: prev[next], other.path, self)
|
|
|
|
def __repr__(self):
|
|
return "%s(%r)" % (self.__class__.__name__, self.path)
|
|
|
|
|
|
class RootRegistry(PathRegistry):
|
|
"""Root registry, defers to mappers so that
|
|
paths are maintained per-root-mapper.
|
|
|
|
"""
|
|
|
|
inherit_cache = True
|
|
|
|
path = natural_path = ()
|
|
has_entity = False
|
|
is_aliased_class = False
|
|
is_root = True
|
|
|
|
def __getitem__(self, entity):
|
|
return entity._path_registry
|
|
|
|
|
|
PathRegistry.root = RootRegistry()
|
|
|
|
|
|
class PathToken(HasCacheKey, str):
|
|
"""cacheable string token"""
|
|
|
|
_intern = {}
|
|
|
|
def _gen_cache_key(self, anon_map, bindparams):
|
|
return (str(self),)
|
|
|
|
@classmethod
|
|
def intern(cls, strvalue):
|
|
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
|
|
|
|
def __init__(self, parent, token):
|
|
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):
|
|
if not self.parent.is_aliased_class and not self.parent.is_root:
|
|
for ent in self.parent.mapper.iterate_to_root():
|
|
yield TokenRegistry(self.parent.parent[ent], self.token)
|
|
elif (
|
|
self.parent.is_aliased_class
|
|
and self.parent.entity._is_with_polymorphic
|
|
):
|
|
yield self
|
|
for ent in self.parent.entity._with_polymorphic_entities:
|
|
yield TokenRegistry(self.parent.parent[ent], self.token)
|
|
else:
|
|
yield self
|
|
|
|
def __getitem__(self, entity):
|
|
raise NotImplementedError()
|
|
|
|
|
|
class PropRegistry(PathRegistry):
|
|
is_unnatural = False
|
|
inherit_cache = True
|
|
|
|
def __init__(self, parent, prop):
|
|
# restate this path in terms of the
|
|
# given MapperProperty's parent.
|
|
insp = inspection.inspect(parent[-1])
|
|
natural_parent = parent
|
|
|
|
if not insp.is_aliased_class or insp._use_mapper_path:
|
|
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 = parent[-1]._entity_for_mapper(prop.parent)
|
|
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._wildcard_path_loader_key = (
|
|
"loader",
|
|
parent.path + self.prop._wildcard_token,
|
|
)
|
|
self._default_path_loader_key = self.prop._default_path_loader_key
|
|
self._loader_key = ("loader", self.natural_path)
|
|
|
|
def __str__(self):
|
|
return " -> ".join(str(elem) for elem in self.path)
|
|
|
|
@util.memoized_property
|
|
def has_entity(self):
|
|
return hasattr(self.prop, "mapper")
|
|
|
|
@util.memoized_property
|
|
def entity(self):
|
|
return self.prop.mapper
|
|
|
|
@property
|
|
def mapper(self):
|
|
return self.entity
|
|
|
|
@property
|
|
def entity_path(self):
|
|
return self[self.entity]
|
|
|
|
def __getitem__(self, entity):
|
|
if isinstance(entity, (int, slice)):
|
|
return self.path[entity]
|
|
else:
|
|
return SlotsEntityRegistry(self, entity)
|
|
|
|
|
|
class AbstractEntityRegistry(PathRegistry):
|
|
__slots__ = ()
|
|
|
|
has_entity = True
|
|
|
|
def __init__(self, parent, entity):
|
|
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.
|
|
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].entity):
|
|
self.natural_path = parent.natural_path + (entity.mapper,)
|
|
else:
|
|
self.natural_path = parent.natural_path + (
|
|
parent.natural_path[-1].entity,
|
|
)
|
|
# 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 cachable 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 = parent.natural_path + (entity, )
|
|
self.natural_path = self.path
|
|
|
|
@property
|
|
def entity_path(self):
|
|
return self
|
|
|
|
@property
|
|
def mapper(self):
|
|
return inspection.inspect(self.entity).mapper
|
|
|
|
def __bool__(self):
|
|
return True
|
|
|
|
__nonzero__ = __bool__
|
|
|
|
def __getitem__(self, entity):
|
|
if isinstance(entity, (int, slice)):
|
|
return self.path[entity]
|
|
else:
|
|
return PropRegistry(self, entity)
|
|
|
|
|
|
class SlotsEntityRegistry(AbstractEntityRegistry):
|
|
# for aliased class, return lightweight, no-cycles created
|
|
# version
|
|
inherit_cache = True
|
|
|
|
__slots__ = (
|
|
"key",
|
|
"parent",
|
|
"is_aliased_class",
|
|
"entity",
|
|
"path",
|
|
"natural_path",
|
|
)
|
|
|
|
|
|
class CachingEntityRegistry(AbstractEntityRegistry, dict):
|
|
# for long lived mapper, return dict based caching
|
|
# version that creates reference cycles
|
|
|
|
inherit_cache = True
|
|
|
|
def __getitem__(self, entity):
|
|
if isinstance(entity, (int, slice)):
|
|
return self.path[entity]
|
|
else:
|
|
return dict.__getitem__(self, entity)
|
|
|
|
def __missing__(self, key):
|
|
self[key] = item = PropRegistry(self, key)
|
|
|
|
return item
|