It should be possible for model classes to have abstract methods

[steven_ganz]

This is 'abstract' in terms of ABCMeta and has nothing to do with setting 'abstract = True' (i.e., use of abstract methods should be possible regardless of the setting of 'abstract')

Any attempt to set

__metaclass__ = ABCMeta

gives:

TypeError: Error when calling the metaclass bases
    metaclass conflict: the metaclass of a derived class must be a (non-strict) subclass of the metaclasses of all its bases

Unfortunately, the solution is not as simple as setting this attribute for Model and ModelBase.

[Aymeric Augustin]

In this scenario __metaclass__ must be a subclass of both Model's metaclass (namely ModelBase) and ABCMeta.

I would advise against using metaclasses if the above isn't obvious to you.