else:
return self
+ .. warning::
+
+ Note that the **behavior of coerce_compared_value is not inherited
+ by default from that of the base type**.
+ If the :class:`.TypeDecorator` is augmenting a
+ type that requires special logic for certain types of operators,
+ this method **must** be overridden. A key example is when decorating
+ the :class:`.postgresql.JSON` and :class:`.postgresql.JSONB` types;
+ the default rules of :meth:`.TypeEngine.coerce_compared_value` should
+ be used in order to deal with operators like index operations::
+
+ class MyJsonType(TypeDecorator):
+ impl = postgresql.JSON
+
+ def coerce_compared_value(self, op, value):
+ return self.impl.coerce_compared_value(op, value)
+
+ Without the above step, index operations such as ``mycol['foo']``
+ will cause the index value ``'foo'`` to be JSON encoded.
+
"""
__visit_name__ = "type_decorator"