Endpoints API - protorpc validation error

Question

I'm getting some weird errors from protorpc when I use endpoints. In this code:

class Application(EndpointsModel):

    _message_fields_schema = ('id', 'name')

    created = ndb.DateTimeProperty(auto_now_add=True)
    name = ndb.StringProperty()
    roles = ndb.IntegerProperty(repeated=True)
    updated = ndb.DateTimeProperty(auto_now=True)
    owner = ndb.KeyProperty(kind='User')

@API.api_class(resource_name="application")
class ApplicationApi(protorpc.remote.Service):

    @Application.method(http_method="GET",
                        request_fields=('id',),
                        name="get",
                        path="applications/{id}")
    def ApplicationGet(self, instance):
        if not instance.from_datastore:
            raise endpoints.NotFoundException("Application not found.")
        return instance

    @Application.query_method(http_method="GET",
                              query_fields=('limit', 'order', 'pageToken'),
                              name="list",
                              path="applications")
    def ApplicationList(self, query):
        return query

when I call application.get() error is as follows: (full trace here):

TypeError: Can only copy from entities of the exact type Application. Received an instance of Application.

and for calling application.list() error is as follows: (full trace here):

ValidationError: Expected type <class '.Application'> for field items, found <Application name: u'test'> (type <class '.Application'>)

What could be causing this? My other models with pretty much the same code (just different properties) work fine.

Ayah

Those traces look like you are using an instance of Application instead of the class(type) object Application. Are you sure you aren't using Application() somewhere in your code? – Infeld

Just double-checked, I'm not using it anywhere - all relevant code is in the question. I am extending a class ApplicationApi(BaseRemoteService), but no mention of Application there, and there's a POST api method (which works...), but even if I remove all that I'm still getting the same errors with just the code from OP. – Ayah

It's a shot in the dark, but prior to subclassing EndpointsModel, did Application subclass ndb.Model? Try looping through all Application entities and doing a put again on them. I'm thinking that the key you pass in fetches the entity but something about the inheritance chain is making the __class__ fields not match. – Infeld

You might be right. The weird thing is Application class didn't subclass anything other then EndpointsModel, but when I subclassed class JsonModel(EndpointsModel) (also did some other things in code, so can't be sure what exactly is happening) it started working. I reverted back to EndpointsModel and it's still workig (; Guess the only way to deal with thiss kind of issues is to turn everything else off and isolate modules with problems... – Ayah

Answer 1

Subclass class JsonModel(EndpointsModel) to make it start working again.

Langtry