class MutableComposite(MutableBase):
Mixin that defines transparent propagation of change events on a SQLAlchemy "composite" object to its owning parent or parents.
See the example in :ref:`mutable_composites` for usage information.
| Method | changed |
Subclasses should call this method whenever change events occur. |
| Class Method | _get_listen_keys |
Given a descriptor attribute, return a set() of the attribute keys which indicate a change in the state of this attribute. |
Inherited from MutableBase:
| Class Method | coerce |
Given a value, coerce it into the target type. |
| Class Method | _listen_on_attribute |
Establish this type as a mutation listener for the given mapped descriptor. |
| Property | _parents |
Dictionary of parent object's .InstanceState->attribute name on the parent. |
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 .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
.InstanceEvents.refresh and
.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.