diff options
Diffstat (limited to 'lib/sqlalchemy/orm/collections.py')
| -rw-r--r-- | lib/sqlalchemy/orm/collections.py | 259 |
1 files changed, 24 insertions, 235 deletions
diff --git a/lib/sqlalchemy/orm/collections.py b/lib/sqlalchemy/orm/collections.py index 75ce8216f..ba4225563 100644 --- a/lib/sqlalchemy/orm/collections.py +++ b/lib/sqlalchemy/orm/collections.py @@ -102,18 +102,20 @@ The owning object and :class:`.CollectionAttributeImpl` are also reachable through the adapter, allowing for some very sophisticated behavior. """ - import operator import threading +import typing import weakref -from sqlalchemy.util.compat import inspect_getfullargspec -from . import base from .. import exc as sa_exc from .. import util -from ..sql import coercions -from ..sql import expression -from ..sql import roles +from ..util.compat import inspect_getfullargspec + +if typing.TYPE_CHECKING: + from .mapped_collection import attribute_mapped_collection + from .mapped_collection import column_mapped_collection + from .mapped_collection import mapped_collection + from .mapped_collection import MappedCollection # noqa: F401 __all__ = [ "collection", @@ -126,180 +128,6 @@ __all__ = [ __instrumentation_mutex = threading.Lock() -class _PlainColumnGetter: - """Plain column getter, stores collection of Column objects - directly. - - Serializes to a :class:`._SerializableColumnGetterV2` - which has more expensive __call__() performance - and some rare caveats. - - """ - - def __init__(self, cols): - self.cols = cols - self.composite = len(cols) > 1 - - def __reduce__(self): - return _SerializableColumnGetterV2._reduce_from_cols(self.cols) - - def _cols(self, mapper): - return self.cols - - def __call__(self, value): - state = base.instance_state(value) - m = base._state_mapper(state) - - key = [ - m._get_state_attr_by_column(state, state.dict, col) - for col in self._cols(m) - ] - - if self.composite: - return tuple(key) - else: - return key[0] - - -class _SerializableColumnGetter: - """Column-based getter used in version 0.7.6 only. - - Remains here for pickle compatibility with 0.7.6. - - """ - - def __init__(self, colkeys): - self.colkeys = colkeys - self.composite = len(colkeys) > 1 - - def __reduce__(self): - return _SerializableColumnGetter, (self.colkeys,) - - def __call__(self, value): - state = base.instance_state(value) - m = base._state_mapper(state) - key = [ - m._get_state_attr_by_column( - state, state.dict, m.mapped_table.columns[k] - ) - for k in self.colkeys - ] - if self.composite: - return tuple(key) - else: - return key[0] - - -class _SerializableColumnGetterV2(_PlainColumnGetter): - """Updated serializable getter which deals with - multi-table mapped classes. - - Two extremely unusual cases are not supported. - Mappings which have tables across multiple metadata - objects, or which are mapped to non-Table selectables - linked across inheriting mappers may fail to function - here. - - """ - - def __init__(self, colkeys): - self.colkeys = colkeys - self.composite = len(colkeys) > 1 - - def __reduce__(self): - return self.__class__, (self.colkeys,) - - @classmethod - def _reduce_from_cols(cls, cols): - def _table_key(c): - if not isinstance(c.table, expression.TableClause): - return None - else: - return c.table.key - - colkeys = [(c.key, _table_key(c)) for c in cols] - return _SerializableColumnGetterV2, (colkeys,) - - def _cols(self, mapper): - cols = [] - metadata = getattr(mapper.local_table, "metadata", None) - for (ckey, tkey) in self.colkeys: - if tkey is None or metadata is None or tkey not in metadata: - cols.append(mapper.local_table.c[ckey]) - else: - cols.append(metadata.tables[tkey].c[ckey]) - return cols - - -def column_mapped_collection(mapping_spec): - """A dictionary-based collection type with column-based keying. - - Returns a :class:`.MappedCollection` factory with a keying function - generated from mapping_spec, which may be a Column or a sequence - of Columns. - - The key value must be immutable for the lifetime of the object. You - can not, for example, map on foreign key values if those key values will - change during the session, i.e. from None to a database-assigned integer - after a session flush. - - """ - cols = [ - coercions.expect(roles.ColumnArgumentRole, q, argname="mapping_spec") - for q in util.to_list(mapping_spec) - ] - keyfunc = _PlainColumnGetter(cols) - return lambda: MappedCollection(keyfunc) - - -class _SerializableAttrGetter: - def __init__(self, name): - self.name = name - self.getter = operator.attrgetter(name) - - def __call__(self, target): - return self.getter(target) - - def __reduce__(self): - return _SerializableAttrGetter, (self.name,) - - -def attribute_mapped_collection(attr_name): - """A dictionary-based collection type with attribute-based keying. - - Returns a :class:`.MappedCollection` factory with a keying based on the - 'attr_name' attribute of entities in the collection, where ``attr_name`` - is the string name of the attribute. - - .. warning:: the key value must be assigned to its final value - **before** it is accessed by the attribute mapped collection. - Additionally, changes to the key attribute are **not tracked** - automatically, which means the key in the dictionary is not - automatically synchronized with the key value on the target object - itself. See the section :ref:`key_collections_mutations` - for an example. - - """ - getter = _SerializableAttrGetter(attr_name) - return lambda: MappedCollection(getter) - - -def mapped_collection(keyfunc): - """A dictionary-based collection type with arbitrary keying. - - Returns a :class:`.MappedCollection` factory with a keying function - generated from keyfunc, a callable that takes an entity and returns a - key value. - - The key value must be immutable for the lifetime of the object. You - can not, for example, map on foreign key values if those key values will - change during the session, i.e. from None to a database-assigned integer - after a session flush. - - """ - return lambda: MappedCollection(keyfunc) - - class collection: """Decorators for entity collection classes. @@ -1620,63 +1448,24 @@ __interfaces = { } -class MappedCollection(dict): - """A basic dictionary-based collection class. - - Extends dict with the minimal bag semantics that collection - classes require. ``set`` and ``remove`` are implemented in terms - of a keying function: any callable that takes an object and - returns an object for use as a dictionary key. - - """ - - def __init__(self, keyfunc): - """Create a new collection with keying provided by keyfunc. +def __go(lcls): - keyfunc may be any callable that takes an object and returns an object - for use as a dictionary key. + global mapped_collection, column_mapped_collection + global attribute_mapped_collection, MappedCollection - The keyfunc will be called every time the ORM needs to add a member by - value-only (such as when loading instances from the database) or - remove a member. The usual cautions about dictionary keying apply- - ``keyfunc(object)`` should return the same output for the life of the - collection. Keying based on mutable properties can result in - unreachable instances "lost" in the collection. + from .mapped_collection import mapped_collection + from .mapped_collection import column_mapped_collection + from .mapped_collection import attribute_mapped_collection + from .mapped_collection import MappedCollection - """ - self.keyfunc = keyfunc - - @collection.appender - @collection.internally_instrumented - def set(self, value, _sa_initiator=None): - """Add an item by value, consulting the keyfunc for the key.""" - - key = self.keyfunc(value) - self.__setitem__(key, value, _sa_initiator) - - @collection.remover - @collection.internally_instrumented - def remove(self, value, _sa_initiator=None): - """Remove an item by value, consulting the keyfunc for the key.""" - - key = self.keyfunc(value) - # Let self[key] raise if key is not in this collection - # testlib.pragma exempt:__ne__ - if self[key] != value: - raise sa_exc.InvalidRequestError( - "Can not remove '%s': collection holds '%s' for key '%s'. " - "Possible cause: is the MappedCollection key function " - "based on mutable properties or properties that only obtain " - "values after flush?" % (value, self[key], key) - ) - self.__delitem__(key, _sa_initiator) + # ensure instrumentation is associated with + # these built-in classes; if a user-defined class + # subclasses these and uses @internally_instrumented, + # the superclass is otherwise not instrumented. + # see [ticket:2406]. + _instrument_class(InstrumentedList) + _instrument_class(InstrumentedSet) + _instrument_class(MappedCollection) -# ensure instrumentation is associated with -# these built-in classes; if a user-defined class -# subclasses these and uses @internally_instrumented, -# the superclass is otherwise not instrumented. -# see [ticket:2406]. -_instrument_class(MappedCollection) -_instrument_class(InstrumentedList) -_instrument_class(InstrumentedSet) +__go(locals()) |