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Diffstat (limited to 'lib/sqlalchemy/ext/mutable.py')
| -rw-r--r-- | lib/sqlalchemy/ext/mutable.py | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/lib/sqlalchemy/ext/mutable.py b/lib/sqlalchemy/ext/mutable.py index e721397b3..ccaeb6aa3 100644 --- a/lib/sqlalchemy/ext/mutable.py +++ b/lib/sqlalchemy/ext/mutable.py @@ -204,6 +204,28 @@ or more parent objects that are also part of the pickle, the :class:`.Mutable` mixin will re-establish the :attr:`.Mutable._parents` collection on each value object as the owning parents themselves are unpickled. +Receiving Events +---------------- + +The :meth:`.AttributeEvents.modified` event handler may be used to receive +an event when a mutable scalar emits a change event. This event handler +is called when the :func:`.attributes.flag_modified` function is called +from within the mutable extension:: + + from sqlalchemy.ext.declarative import declarative_base + from sqlalchemy import event + + Base = declarative_base() + + class MyDataClass(Base): + __tablename__ = 'my_data' + id = Column(Integer, primary_key=True) + data = Column(MutableDict.as_mutable(JSONEncodedDict)) + + @event.listens_for(MyDataClass.data, "modified") + def modified_json(instance): + print("json value modified:", instance.data) + .. _mutable_composites: Establishing Mutability on Composites |