diff options
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/sqlalchemy/orm/attributes.py | 135 | ||||
| -rw-r--r-- | lib/sqlalchemy/orm/dynamic.py | 7 | ||||
| -rw-r--r-- | lib/sqlalchemy/orm/events.py | 33 |
3 files changed, 123 insertions, 52 deletions
diff --git a/lib/sqlalchemy/orm/attributes.py b/lib/sqlalchemy/orm/attributes.py index 13c2cf256..f4f0cc782 100644 --- a/lib/sqlalchemy/orm/attributes.py +++ b/lib/sqlalchemy/orm/attributes.py @@ -398,6 +398,59 @@ def create_proxied_attribute(descriptor): from_instance=descriptor) return Proxy +OP_REMOVE = util.symbol("REMOVE") +OP_APPEND = util.symbol("APPEND") +OP_REPLACE = util.symbol("REPLACE") + +class Event(object): + """A token propagated throughout the course of a chain of attribute + events. + + Serves as an indicator of the source of the event and also provides + a means of controlling propagation across a chain of attribute + operations. + + The :class:`.Event` object is sent as the ``initiator`` argument + when dealing with the :meth:`.AttributeEvents.append`, + :meth:`.AttributeEvents.set`, + and :meth:`.AttributeEvents.remove` events. + + The :class:`.Event` object is currently interpreted by the backref + event handlers, and is used to control the propagation of operations + across two mutually-dependent attributes. + + .. versionadded:: 0.9.0 + + """ + + impl = None + """The :class:`.AttributeImpl` which is the current event initiator. + """ + + op = None + """The symbol :attr:`.OP_APPEND`, :attr:`.OP_REMOVE` or :attr:`.OP_REPLACE`, + indicating the source operation. + + """ + + def __init__(self, attribute_impl, op): + self.impl = attribute_impl + self.op = op + self.parent_token = self.impl.parent_token + + @classmethod + def _token_gen(self, op): + @util.memoized_property + def gen(self): + return Event(self, op) + return gen + + @property + def key(self): + return self.impl.key + + def hasparent(self, state): + return self.impl.hasparent(state) class AttributeImpl(object): """internal implementation for instrumented attributes.""" @@ -683,7 +736,7 @@ class ScalarAttributeImpl(AttributeImpl): old = dict_.get(self.key, NO_VALUE) if self.dispatch.remove: - self.fire_remove_event(state, dict_, old, None) + self.fire_remove_event(state, dict_, old, self._remove_token) state._modified_event(dict_, self, old) del dict_[self.key] @@ -693,9 +746,6 @@ class ScalarAttributeImpl(AttributeImpl): def set(self, state, dict_, value, initiator, passive=PASSIVE_OFF, check_old=None, pop=False): - if initiator and initiator.parent_token is self.parent_token: - return - if self.dispatch._active_history: old = self.get(state, dict_, PASSIVE_RETURN_NEVER_SET) else: @@ -707,14 +757,17 @@ class ScalarAttributeImpl(AttributeImpl): state._modified_event(dict_, self, old) dict_[self.key] = value + _replace_token = _append_token = Event._token_gen(OP_REPLACE) + _remove_token = Event._token_gen(OP_REMOVE) + def fire_replace_event(self, state, dict_, value, previous, initiator): for fn in self.dispatch.set: - value = fn(state, value, previous, initiator or self) + value = fn(state, value, previous, initiator or self._replace_token) return value def fire_remove_event(self, state, dict_, value, initiator): for fn in self.dispatch.remove: - fn(state, value, initiator or self) + fn(state, value, initiator or self._remove_token) @property def type(self): @@ -736,7 +789,7 @@ class ScalarObjectAttributeImpl(ScalarAttributeImpl): def delete(self, state, dict_): old = self.get(state, dict_) - self.fire_remove_event(state, dict_, old, self) + self.fire_remove_event(state, dict_, old, self._remove_token) del dict_[self.key] def get_history(self, state, dict_, passive=PASSIVE_OFF): @@ -773,14 +826,7 @@ class ScalarObjectAttributeImpl(ScalarAttributeImpl): passive=PASSIVE_OFF, check_old=None, pop=False): """Set a value on the given InstanceState. - `initiator` is the ``InstrumentedAttribute`` that initiated the - ``set()`` operation and is used to control the depth of a circular - setter operation. - """ - if initiator and initiator.parent_token is self.parent_token: - return - if self.dispatch._active_history: old = self.get(state, dict_, passive=PASSIVE_ONLY_PERSISTENT) else: @@ -801,12 +847,13 @@ class ScalarObjectAttributeImpl(ScalarAttributeImpl): value = self.fire_replace_event(state, dict_, value, old, initiator) dict_[self.key] = value + def fire_remove_event(self, state, dict_, value, initiator): if self.trackparent and value is not None: self.sethasparent(instance_state(value), state, False) for fn in self.dispatch.remove: - fn(state, value, initiator or self) + fn(state, value, initiator or self._remove_token) state._modified_event(dict_, self, value) @@ -818,7 +865,7 @@ class ScalarObjectAttributeImpl(ScalarAttributeImpl): self.sethasparent(instance_state(previous), state, False) for fn in self.dispatch.set: - value = fn(state, value, previous, initiator or self) + value = fn(state, value, previous, initiator or self._replace_token) state._modified_event(dict_, self, previous) @@ -902,9 +949,12 @@ class CollectionAttributeImpl(AttributeImpl): return [(instance_state(o), o) for o in current] + _append_token = Event._token_gen(OP_APPEND) + _remove_token = Event._token_gen(OP_REMOVE) + def fire_append_event(self, state, dict_, value, initiator): for fn in self.dispatch.append: - value = fn(state, value, initiator or self) + value = fn(state, value, initiator or self._append_token) state._modified_event(dict_, self, NEVER_SET, True) @@ -921,7 +971,7 @@ class CollectionAttributeImpl(AttributeImpl): self.sethasparent(instance_state(value), state, False) for fn in self.dispatch.remove: - fn(state, value, initiator or self) + fn(state, value, initiator or self._remove_token) state._modified_event(dict_, self, NEVER_SET, True) @@ -948,8 +998,6 @@ class CollectionAttributeImpl(AttributeImpl): self.key, state, self.collection_factory) def append(self, state, dict_, value, initiator, passive=PASSIVE_OFF): - if initiator and initiator.parent_token is self.parent_token: - return collection = self.get_collection(state, dict_, passive=passive) if collection is PASSIVE_NO_RESULT: value = self.fire_append_event(state, dict_, value, initiator) @@ -960,9 +1008,6 @@ class CollectionAttributeImpl(AttributeImpl): collection.append_with_event(value, initiator) def remove(self, state, dict_, value, initiator, passive=PASSIVE_OFF): - if initiator and initiator.parent_token is self.parent_token: - return - collection = self.get_collection(state, state.dict, passive=passive) if collection is PASSIVE_NO_RESULT: self.fire_remove_event(state, dict_, value, initiator) @@ -985,14 +1030,8 @@ class CollectionAttributeImpl(AttributeImpl): passive=PASSIVE_OFF, pop=False): """Set a value on the given object. - `initiator` is the ``InstrumentedAttribute`` that initiated the - ``set()`` operation and is used to control the depth of a circular - setter operation. """ - if initiator and initiator.parent_token is self.parent_token: - return - self._set_iterable( state, dict_, value, lambda adapter, i: adapter.adapt_like_to_iterable(i)) @@ -1085,6 +1124,7 @@ def backref_listeners(attribute, key, uselist): # use easily recognizable names for stack traces parent_token = attribute.impl.parent_token + parent_impl = attribute.impl def _acceptable_key_err(child_state, initiator, child_impl): raise ValueError( @@ -1108,10 +1148,14 @@ def backref_listeners(attribute, key, uselist): old_state, old_dict = instance_state(oldchild),\ instance_dict(oldchild) impl = old_state.manager[key].impl - impl.pop(old_state, - old_dict, - state.obj(), - initiator, passive=PASSIVE_NO_FETCH) + + if initiator.impl is not impl or \ + initiator.op not in (OP_REPLACE, OP_REMOVE): + impl.pop(old_state, + old_dict, + state.obj(), + parent_impl._append_token, + passive=PASSIVE_NO_FETCH) if child is not None: child_state, child_dict = instance_state(child),\ @@ -1120,12 +1164,14 @@ def backref_listeners(attribute, key, uselist): if initiator.parent_token is not parent_token and \ initiator.parent_token is not child_impl.parent_token: _acceptable_key_err(state, initiator, child_impl) - child_impl.append( - child_state, - child_dict, - state.obj(), - initiator, - passive=PASSIVE_NO_FETCH) + elif initiator.impl is not child_impl or \ + initiator.op not in (OP_APPEND, OP_REPLACE): + child_impl.append( + child_state, + child_dict, + state.obj(), + initiator, + passive=PASSIVE_NO_FETCH) return child def emit_backref_from_collection_append_event(state, child, initiator): @@ -1139,7 +1185,9 @@ def backref_listeners(attribute, key, uselist): if initiator.parent_token is not parent_token and \ initiator.parent_token is not child_impl.parent_token: _acceptable_key_err(state, initiator, child_impl) - child_impl.append( + elif initiator.impl is not child_impl or \ + initiator.op not in (OP_APPEND, OP_REPLACE): + child_impl.append( child_state, child_dict, state.obj(), @@ -1152,10 +1200,9 @@ def backref_listeners(attribute, key, uselist): child_state, child_dict = instance_state(child),\ instance_dict(child) child_impl = child_state.manager[key].impl - # can't think of a path that would produce an initiator - # mismatch here, as it would require an existing collection - # mismatch. - child_impl.pop( + if initiator.impl is not child_impl or \ + initiator.op not in (OP_REMOVE, OP_REPLACE): + child_impl.pop( child_state, child_dict, state.obj(), diff --git a/lib/sqlalchemy/orm/dynamic.py b/lib/sqlalchemy/orm/dynamic.py index 5814b47ca..fb46713d0 100644 --- a/lib/sqlalchemy/orm/dynamic.py +++ b/lib/sqlalchemy/orm/dynamic.py @@ -78,6 +78,9 @@ class DynamicAttributeImpl(attributes.AttributeImpl): history = self._get_collection_history(state, passive) return history.added_plus_unchanged + _append_token = attributes.Event._token_gen(attributes.OP_APPEND) + _remove_token = attributes.Event._token_gen(attributes.OP_REMOVE) + def fire_append_event(self, state, dict_, value, initiator, collection_history=None): if collection_history is None: @@ -86,7 +89,7 @@ class DynamicAttributeImpl(attributes.AttributeImpl): collection_history.add_added(value) for fn in self.dispatch.append: - value = fn(state, value, initiator or self) + value = fn(state, value, initiator or self._append_token) if self.trackparent and value is not None: self.sethasparent(attributes.instance_state(value), state, True) @@ -102,7 +105,7 @@ class DynamicAttributeImpl(attributes.AttributeImpl): self.sethasparent(attributes.instance_state(value), state, False) for fn in self.dispatch.remove: - fn(state, value, initiator or self) + fn(state, value, initiator or self._remove_token) def _modified_event(self, state, dict_): diff --git a/lib/sqlalchemy/orm/events.py b/lib/sqlalchemy/orm/events.py index 14b3a770e..9a7190746 100644 --- a/lib/sqlalchemy/orm/events.py +++ b/lib/sqlalchemy/orm/events.py @@ -1561,8 +1561,15 @@ class AttributeEvents(event.Events): is registered with ``retval=True``, the listener function must return this value, or a new value which replaces it. - :param initiator: the attribute implementation object - which initiated this event. + :param initiator: An instance of :class:`.attributes.Event` + representing the initiation of the event. May be modified + from it's original value by backref handlers in order to control + chained event propagation. + + .. versionchanged:: 0.9.0 the ``initiator`` argument is now + passed as a :class:`.attributes.Event` object, and may be modified + by backref handlers within a chain of backref-linked events. + :return: if the event was registered with ``retval=True``, the given value, or a new effective value, should be returned. @@ -1575,8 +1582,15 @@ class AttributeEvents(event.Events): If the listener is registered with ``raw=True``, this will be the :class:`.InstanceState` object. :param value: the value being removed. - :param initiator: the attribute implementation object - which initiated this event. + :param initiator: An instance of :class:`.attributes.Event` + representing the initiation of the event. May be modified + from it's original value by backref handlers in order to control + chained event propagation. + + .. versionchanged:: 0.9.0 the ``initiator`` argument is now + passed as a :class:`.attributes.Event` object, and may be modified + by backref handlers within a chain of backref-linked events. + :return: No return value is defined for this event. """ @@ -1596,8 +1610,15 @@ class AttributeEvents(event.Events): the previous value of the attribute will be loaded from the database if the existing value is currently unloaded or expired. - :param initiator: the attribute implementation object - which initiated this event. + :param initiator: An instance of :class:`.attributes.Event` + representing the initiation of the event. May be modified + from it's original value by backref handlers in order to control + chained event propagation. + + .. versionchanged:: 0.9.0 the ``initiator`` argument is now + passed as a :class:`.attributes.Event` object, and may be modified + by backref handlers within a chain of backref-linked events. + :return: if the event was registered with ``retval=True``, the given value, or a new effective value, should be returned. |