diff options
Diffstat (limited to 'lib/sqlalchemy/ext/associationproxy.py')
| -rw-r--r-- | lib/sqlalchemy/ext/associationproxy.py | 63 |
1 files changed, 42 insertions, 21 deletions
diff --git a/lib/sqlalchemy/ext/associationproxy.py b/lib/sqlalchemy/ext/associationproxy.py index d6a995450..1b363c9ac 100644 --- a/lib/sqlalchemy/ext/associationproxy.py +++ b/lib/sqlalchemy/ext/associationproxy.py @@ -10,6 +10,7 @@ from sqlalchemy.orm.attributes import InstrumentedList import sqlalchemy.exceptions as exceptions import sqlalchemy.orm as orm import sqlalchemy.util as util +import weakref def association_proxy(targetcollection, attr, **kw): """Convenience function for use in mapped classes. Implements a Python @@ -116,6 +117,18 @@ class AssociationProxy(object): def _target_is_scalar(self): return not self._get_property().uselist + + def _lazy_collection(self, weakobjref): + target = self.target_collection + del self + def lazy_collection(): + obj = weakobjref() + if obj is None: + raise exceptions.InvalidRequestError( + "stale association proxy, parent object has gone out of " + "scope") + return getattr(obj, target) + return lazy_collection def __get__(self, obj, class_): if obj is None: @@ -130,7 +143,7 @@ class AssociationProxy(object): try: return getattr(obj, self.key) except AttributeError: - proxy = self._new(getattr(obj, self.target_collection)) + proxy = self._new(self._lazy_collection(weakref.ref(obj))) setattr(obj, self.key, proxy) return proxy @@ -153,30 +166,32 @@ class AssociationProxy(object): def __delete__(self, obj): delattr(obj, self.key) - def _new(self, collection): + def _new(self, lazy_collection): creator = self.creator and self.creator or self.target_class # Prefer class typing here to spot dicts with the required append() # method. + collection = lazy_collection() if isinstance(collection.data, dict): self.collection_class = dict else: self.collection_class = util.duck_type_collection(collection.data) + del collection if self.proxy_factory: - return self.proxy_factory(collection, creator, self.value_attr) + return self.proxy_factory(lazy_collection, creator, self.value_attr) value_attr = self.value_attr getter = lambda o: getattr(o, value_attr) setter = lambda o, v: setattr(o, value_attr, v) if self.collection_class is list: - return _AssociationList(collection, creator, getter, setter) + return _AssociationList(lazy_collection, creator, getter, setter) elif self.collection_class is dict: kv_setter = lambda o, k, v: setattr(o, value_attr, v) - return _AssociationDict(collection, creator, getter, setter) + return _AssociationDict(lazy_collection, creator, getter, setter) elif self.collection_class is util.Set: - return _AssociationSet(collection, creator, getter, setter) + return _AssociationSet(lazy_collection, creator, getter, setter) else: raise exceptions.ArgumentError( 'could not guess which interface to use for ' @@ -203,11 +218,11 @@ class _AssociationList(object): converting association objects to and from a simplified value. """ - def __init__(self, collection, creator, getter, setter): + def __init__(self, lazy_collection, creator, getter, setter): """ - collection - A list-based collection of entities (usually an object attribute - managed by a SQLAlchemy relation()) + lazy_collection + A callable returning a list-based collection of entities (usually + an object attribute managed by a SQLAlchemy relation()) creator A function that creates new target entities. Given one parameter: @@ -223,11 +238,13 @@ class _AssociationList(object): that value on the object. """ - self.col = collection + self.lazy_collection = lazy_collection self.creator = creator self.getter = getter self.setter = setter + col = property(lambda self: self.lazy_collection()) + # For compatibility with 0.3.1 through 0.3.7- pass kw through to creator. # (see append() below) def _create(self, value, **kw): @@ -320,11 +337,11 @@ class _AssociationDict(object): converting association objects to and from a simplified value. """ - def __init__(self, collection, creator, getter, setter): + def __init__(self, lazy_collection, creator, getter, setter): """ - collection - A list-based collection of entities (usually an object attribute - managed by a SQLAlchemy relation()) + lazy_collection + A callable returning a dict-based collection of entities (usually + an object attribute managed by a SQLAlchemy relation()) creator A function that creates new target entities. Given two parameters: @@ -340,11 +357,13 @@ class _AssociationDict(object): that value on the object. """ - self.col = collection + self.lazy_collection = lazy_collection self.creator = creator self.getter = getter self.setter = setter + col = property(lambda self: self.lazy_collection()) + def _create(self, key, value): return self.creator(key, value) @@ -380,7 +399,7 @@ class _AssociationDict(object): has_key = __contains__ def __iter__(self): - return iter(self.col) + return self.col.iterkeys() def clear(self): self.col.clear() @@ -465,11 +484,11 @@ class _AssociationSet(object): converting association objects to and from a simplified value. """ - def __init__(self, collection, creator, getter, setter): + def __init__(self, lazy_collection, creator, getter, setter): """ collection - A list-based collection of entities (usually an object attribute - managed by a SQLAlchemy relation()) + A callable returning a set-based collection of entities (usually an + object attribute managed by a SQLAlchemy relation()) creator A function that creates new target entities. Given one parameter: @@ -485,11 +504,13 @@ class _AssociationSet(object): that value on the object. """ - self.col = collection + self.lazy_collection = lazy_collection self.creator = creator self.getter = getter self.setter = setter + col = property(lambda self: self.lazy_collection()) + def _create(self, value): return self.creator(value) |