def contribute_to_class(self, cls, name, *args, **kwargs):
        @classproperty
        def river(_self):
            return RiverObject(_self)

        self.field_name = name

        self._add_to_class(cls, self.field_name + "_transition_approvals",
                           GenericRelation('%s.%s' % (TransitionApproval._meta.app_label, TransitionApproval._meta.object_name)))
        self._add_to_class(cls, self.field_name + "_transitions", GenericRelation('%s.%s' % (Transition._meta.app_label, Transition._meta.object_name)))

        if id(cls) not in workflow_registry.workflows:
            self._add_to_class(cls, "river", river)

        super(StateField, self).contribute_to_class(cls, name, *args, **kwargs)

        if id(cls) not in workflow_registry.workflows:
            post_save.connect(_on_workflow_object_saved, self.model, False, dispatch_uid='%s_%s_riverstatefield_post' % (self.model, name))
            post_delete.connect(_on_workflow_object_deleted, self.model, False, dispatch_uid='%s_%s_riverstatefield_post' % (self.model, name))

        workflow_registry.add(self.field_name, cls) 

def _register_model(admin, model):
    if not hasattr(admin, 'revision_manager'):
        admin.revision_manager = default_revision_manager
    if not hasattr(admin, 'reversion_format'):
        admin.reversion_format = 'json'

    if not admin.revision_manager.is_registered(model):
        inline_fields = []
        for inline in getattr(admin, 'inlines', []):
            inline_model = inline.model
            if getattr(inline, 'generic_inline', False):
                ct_field = getattr(inline, 'ct_field', 'content_type')
                ct_fk_field = getattr(inline, 'ct_fk_field', 'object_id')
                for field in model._meta.many_to_many:
                    if isinstance(field, GenericRelation) and field.rel.to == inline_model and field.object_id_field_name == ct_fk_field and field.content_type_field_name == ct_field:
                        inline_fields.append(field.name)
                _autoregister(admin, inline_model)
            else:
                fk_name = getattr(inline, 'fk_name', None)
                if not fk_name:
                    for field in inline_model._meta.fields:
                        if isinstance(field, (models.ForeignKey, models.OneToOneField)) and issubclass(model, field.rel.to):
                            fk_name = field.name
                _autoregister(admin, inline_model, follow=[fk_name])
                if not inline_model._meta.get_field(fk_name).rel.is_hidden():
                    accessor = inline_model._meta.get_field(
                        fk_name).related.get_accessor_name()
                    inline_fields.append(accessor)
        _autoregister(admin, model, inline_fields)