Ming MapperExtenstions usage

Question

from ming.odm.mapper import MapperExtension
class MyExtension(MapperExtension):
    def after_insert(self, obj, st):
        print "instance %s after insert !" % obj

class MyMappedClass(MappedClass):
    class __mongometa__:
        session = session
        name = 'my_mapped_class'
        extensions = [ MyExtension ]

    _id = FieldProperty(schema.ObjectId)
    data = FieldProperty(schema.String,if_missing='')

I've tried to use MapperExtension from the official Ming Documentation. and on creating document I'm getting:

t = model.MyMappedClass()
model._session.flush()

TypeError: before_insert() takes exactly 3 arguments (4 given)

Answer 1

It turns out that the MapperExtension base class has a bug which has now been fixed on the master branch and in the docs.