Django Tastypie “ToManyField” in “parent” resource seems to break POST to chile resource

Question

I am using Django 1.4.3 and TastyPie 0.9.11.

I have the following two django models:

class Event(models.Model):
    organizer = models.ForeignKey(User, related_name='Organizador')
    store = models.ForeignKey(Store, related_name='Tienda')
    name = models.CharField('Titulo', max_length=50)
    event_time = models.DateTimeField('Fecha y Hora del Evento')
    creation_date = models.DateTimeField('Fecha de Creación', auto_now_add=True)
    requires_confirmation = models.BooleanField('Require Confirmación')

    class Meta:
        verbose_name = "Encuentro"
        verbose_name_plural = "Encuentros"


class EventInvitees(models.Model):
    event = models.ForeignKey(Event, related_name='invitees')
    invitee = models.ForeignKey(User, verbose_name='Invitado')
    confirmed = models.BooleanField('Confirmado')
    confirmation_date = models.DateTimeField('Fecha de Confirmación', null=True, auto_now=True)

    class Meta:
        verbose_name = "Invitados"
        verbose_name_plural = "Invitados"

Then I have the following API Resources:

class EventInviteesResource(ModelResource):
    user = fields.ForeignKey(UserResource, 'invitee', full=True)
    event = fields.ForeignKey('bbservices.api.EventResource', 'event')

    class Meta:
        queryset = EventInvitees.objects.all()
        authentication = ApiKeyAuthentication()
        authorization = Authorization()


class EventResource(ModelResource):
    invitees = fields.ToManyField('bbservices.api.EventInviteesResource', 'invitees', full=True)
    store = fields.ForeignKey(StoreResource, 'store', full=True)

    class Meta:
        #default_format = 'application/json'

        queryset = Event.objects.all()

        fields = ['organizer_id', 'store', 'name', 'event_time', 'requires_confirmation']
        include_resource_uri = False
        #list_allowed_methods = ['get', 'post']
        authentication = ApiKeyAuthentication()
        authorization = Authorization()
        filtering = {
            #'user': ALL_WITH_RELATIONS
            'event_time': ['exact', 'range', 'gt', 'gte', 'lt', 'lte'],
        }

    def dehydrate_event_time(self, bundle):
        return bundle.data['event_time']

    def obj_create(self, bundle, request=None, **kwargs):
        return super(EventResource, self).obj_create(bundle, request, organizer_id=request.user.pk, store_id=bundle.data['store_id'])

As you can see, I have set up a "ToManyField" relation ship in order to have Event Invitees to show up in GET lists of the Events resource. This works Correctly. Please note that there is also an FK relationship to a "store" and this also works.

The error comes when POSTing the following to "EventInviteesResource" to create and EventInvitee:

POST http://X.X.X.X:8000/api/v1/eventinvitees/?username=user&api_key=XXXXXXX

{
  "event" : {"pk" : 30},
  "invitee" : 2,
  "confirmed" : true
}

The error returned is:

"The 'invitees' field has no data and doesn't allow a null value."

Note that "invitees" does NOT exist in the "EventInviteesResource" but instead in the "parent" resource "EventResource". So I dont understand how this can even be an error. If I comment out the this line:

invitees = fields.ToManyField('bbservices.api.EventInviteesResource', 'invitees', full=True)

the resource "EventResource" the "invitees" error goes away and the error becomes:

{"error_message": "", "traceback": "Traceback (most recent call last):\n\n File \"/Library/Python/2.7/site-packages/tastypie/resources.py\", line 192, in wrapper\n response = callback(request, *args, **kwargs)\n\n File \"/Library/Python/2.7/site-packages/tastypie/resources.py\", line 397, in dispatch_list\n return self.dispatch('list', request, **kwargs)\n\n File \"/Library/Python/2.7/site-packages/tastypie/resources.py\", line 427, in dispatch\n response = method(request, **kwargs)\n\n File \"/Library/Python/2.7/site-packages/tastypie/resources.py\", line 1165, in post_list\n updated_bundle = self.obj_create(bundle, request=request, **self.remove_api_resource_names(kwargs))\n\n File \"/Library/Python/2.7/site-packages/tastypie/resources.py\", line 1774, in obj_create\n bundle = self.full_hydrate(bundle)\n\n File \"/Library/Python/2.7/site-packages/tastypie/resources.py\", line 698, in full_hydrate\n value = field_object.hydrate(bundle)\n\n File \"/Library/Python/2.7/site-packages/tastypie/fields.py\", line 636, in hydrate\n value = super(ToOneField, self).hydrate(bundle)\n\n File \"/Library/Python/2.7/site-packages/tastypie/fields.py\", line 154, in hydrate\n elif self.attribute and getattr(bundle.obj, self.attribute, None):\n\n File \"/Library/Python/2.7/site-packages/django/db/models/fields/related.py\", line 343, in __get__\n raise self.field.rel.to.DoesNotExist\n\nDoesNotExist\n"}

If I try to POST this:

{
    "store_id" : 1, 
    "name" : "With Invitees", 
    "event_time" : "2013-02-06T18:30-3:00",
    "requires_confirmation" : true,
    "invitees" : [
                    {
                      "invitee": {"pk" : 1}
                    }
                ]
}

to the resource EventResource, with the 'invitees' relationship intact, the error is:

{"error_message": "int() argument must be a string or a number, not 'dict'", "traceback": "Traceback (most recent call last):\n\n File \"/Library/Python/2.7/site-packages/tastypie/resources.py\", line 192, in wrapper\n response = callback(request, *args, **kwargs)\n\n File \"/Library/Python/2.7/site-packages/tastypie/resources.py\", line 397, in dispatch_list\n return self.dispatch('list', request, **kwargs)\n\n File \"/Library/Python/2.7/site-packages/tastypie/resources.py\", line 427, in dispatch\n response = method(request, **kwargs)\n\n File \"/Library/Python/2.7/site-packages/tastypie/resources.py\", line 1165, in post_list\n updated_bundle = self.obj_create(bundle, request=request, **self.remove_api_resource_names(kwargs))\n\n File \"/Users/jleidigh/Documents/Starbucks - In Office/trunk/backend/bbservices/api.py\", line 234, in obj_create\n return super(EventResource, self).obj_create(bundle, request, organizer_id=request.user.pk, store_id=bundle.data['store_id'])\n\n File \"/Library/Python/2.7/site-packages/tastypie/resources.py\", line 1783, in obj_create\n m2m_bundle = self.hydrate_m2m(bundle)\n\n File \"/Library/Python/2.7/site-packages/tastypie/resources.py\", line 743, in hydrate_m2m\n bundle.data[field_name] = field_object.hydrate_m2m(bundle)\n\n File \"/Library/Python/2.7/site-packages/tastypie/fields.py\", line 742, in hydrate_m2m\n m2m_hydrated.append(self.build_related_resource(value, **kwargs))\n\n File \"/Library/Python/2.7/site-packages/tastypie/fields.py\", line 593, in build_related_resource\n return self.resource_from_data(self.fk_resource, value, **kwargs)\n\n File \"/Library/Python/2.7/site-packages/tastypie/fields.py\", line 548, in resource_from_data\n return fk_resource.obj_update(fk_bundle, **data)\n\n File \"/Library/Python/2.7/site-packages/tastypie/resources.py\", line 1814, in obj_update\n bundle.obj = self.obj_get(request, **lookup_kwargs)\n\n File \"/Library/Python/2.7/site-packages/tastypie/resources.py\", line 1752, in obj_get\n base_object_list = self.get_object_list(request).filter(**kwargs)\n\n File \"/Library/Python/2.7/site-packages/django/db/models/query.py\", line 624, in filter\n return self._filter_or_exclude(False, *args, **kwargs)\n\n File \"/Library/Python/2.7/site-packages/django/db/models/query.py\", line 642, in _filter_or_exclude\n clone.query.add_q(Q(*args, **kwargs))\n\n File \"/Library/Python/2.7/site-packages/django/db/models/sql/query.py\", line 1250, in add_q\n can_reuse=used_aliases, force_having=force_having)\n\n File \"/Library/Python/2.7/site-packages/django/db/models/sql/query.py\", line 1185, in add_filter\n connector)\n\n File \"/Library/Python/2.7/site-packages/django/db/models/sql/where.py\", line 69, in add\n value = obj.prepare(lookup_type, value)\n\n File \"/Library/Python/2.7/site-packages/django/db/models/sql/where.py\", line 320, in prepare\n return self.field.get_prep_lookup(lookup_type, value)\n\n File \"/Library/Python/2.7/site-packages/django/db/models/fields/related.py\", line 137, in get_prep_lookup\n return self._pk_trace(value, 'get_prep_lookup', lookup_type)\n\n File \"/Library/Python/2.7/site-packages/django/db/models/fields/related.py\", line 210, in _pk_trace\n v = getattr(field, prep_func)(lookup_type, v, **kwargs)\n\n File \"/Library/Python/2.7/site-packages/django/db/models/fields/__init__.py\", line 310, in get_prep_lookup\n return self.get_prep_value(value)\n\n File \"/Library/Python/2.7/site-packages/django/db/models/fields/__init__.py\", line 537, in get_prep_value\n return int(value)\n\nTypeError: int() argument must be a string or a number, not 'dict'\n"}

I believe this error is documented here:

https://github.com/toastdriven/django-tastypie/issues/307

If I comment the "invitees" line and POST to EventResource the error disappears but of course the invitees are not created.

So........any one have any ideas? Is this just another error associated with issue 307 (link above) or am I doing something wrong??

Thanks very much in advance!!!!

Answer 1

OK, I found my own answer. In EventInviteesResource

user = fields.ForeignKey(UserResource, 'invitee', full=True)

Needs to be the following in order to mirror my Django Model:

invitee = fields.ForeignKey(UserResource, 'invitee', full=True)

While this DOES seem logical, I must say that the "invitees" (notice the "s") error I was getting does NOT but oh well...

Bonus Answer, in EventResource, update:

invitees = fields.ToManyField('bbservices.api.EventInviteesResource', 'invitees', full=True)

To:

invitees = fields.ToManyField('bbservices.api.EventInviteesResource', 'invitees', related_name='event', full=True)

An now you can post to EventResource with invitees and have those created automatically as well. The post data would look like this:

{
    "store" : "/api/v1/store/2/", 
    "name" : "Yes again?", 
    "event_time" : "2013-02-06T18:30-3:00",
    "requires_confirmation" : true,
    "invitees" : [
                    {
                      "invitee" : "/api/v1/user/1/",
                      "confirmed" : true
                    }
                ]
}

So now my only doubt is...can anyone tell me why I cant use the PK syntax for FKs:

{ "store" : {"pk" : 2}, ...

This results in errors stating that fields for the Store object cannot be null as if it was try to create a new store object. If I use the URI path as below it works fine:

{ "store" : "/api/v1/store/2/", ...

But I would prefer not to have to pass back the full URI and I should have to. That is why I'm using the store_id trick in obj_create but its VERY kludgy...

Any ideas?

Answer 2

When you provide {"store":"/api/v1/store/2/"} you only specify the store value of an EventResource. But when you provide {"store": {"pk":2}} you do not only specify the value of store but also edit the store (save the related object). That is tastypie "style".

What we can do is to build a set of Javascript function that automatically convert from/to resource uri. Using existing Javascript MVC Frameworks like AgularJS or Backbone as Front End and Django Tastypie as Back End are very powerful.