diff options
Diffstat (limited to 'lib/sqlalchemy/ext/mutable.py')
| -rw-r--r-- | lib/sqlalchemy/ext/mutable.py | 35 |
1 files changed, 34 insertions, 1 deletions
diff --git a/lib/sqlalchemy/ext/mutable.py b/lib/sqlalchemy/ext/mutable.py index 24fc37a42..501b18f39 100644 --- a/lib/sqlalchemy/ext/mutable.py +++ b/lib/sqlalchemy/ext/mutable.py @@ -403,6 +403,27 @@ class MutableBase(object): raise ValueError(msg % (key, type(value))) @classmethod + def _get_listen_keys(cls, attribute): + """Given a descriptor attribute, return a ``set()`` of the attribute + keys which indicate a change in the state of this attribute. + + This is normally just ``set([attribute.key])``, but can be overridden + to provide for additional keys. E.g. a :class:`.MutableComposite` + augments this set with the attribute keys associated with the columns + that comprise the composite value. + + This collection is consulted in the case of intercepting the + :meth:`.InstanceEvents.refresh` and + :meth:`.InstanceEvents.refresh_flush` events, which pass along a list + of attribute names that have been refreshed; the list is compared + against this set to determine if action needs to be taken. + + .. versionadded:: 1.0.5 + + """ + return set([attribute.key]) + + @classmethod def _listen_on_attribute(cls, attribute, coerce, parent_cls): """Establish this type as a mutation listener for the given mapped descriptor. @@ -415,6 +436,8 @@ class MutableBase(object): # rely on "propagate" here parent_cls = attribute.class_ + listen_keys = cls._get_listen_keys(attribute) + def load(state, *args): """Listen for objects loaded or refreshed. @@ -429,6 +452,10 @@ class MutableBase(object): state.dict[key] = val val._parents[state.obj()] = key + def load_attrs(state, ctx, attrs): + if not attrs or listen_keys.intersection(attrs): + load(state) + def set(target, value, oldvalue, initiator): """Listen for set/replace events on the target data member. @@ -463,7 +490,9 @@ class MutableBase(object): event.listen(parent_cls, 'load', load, raw=True, propagate=True) - event.listen(parent_cls, 'refresh', load, + event.listen(parent_cls, 'refresh', load_attrs, + raw=True, propagate=True) + event.listen(parent_cls, 'refresh_flush', load_attrs, raw=True, propagate=True) event.listen(attribute, 'set', set, raw=True, retval=True, propagate=True) @@ -574,6 +603,10 @@ class MutableComposite(MutableBase): """ + @classmethod + def _get_listen_keys(cls, attribute): + return set([attribute.key]).union(attribute.property._attribute_keys) + def changed(self): """Subclasses should call this method whenever change events occur.""" |