Django-Rest-Framework updating a foreign key BY Id

Question

I am using django-rest-framework to build out the back end. I have the list running fine, but (using the django-rest-framework admin screen) I cannot create an object by just using the Id fields of the foreign key objects. I hope I have this configured incorrectly, but I am open to writing some code if i have to :) I am learning django/python from a .NET and Java background and may have become a touch spoiled by this new stack.

Edit: I am trying not to use two different Model classes- I shouldn't have to right?

Thanks in advance.

From Chrome - the key bits of the request

Request URL:http://127.0.0.1:8000/rest/favorite_industries/ 
Request Method:POST 
_content_type:application/json
_content:{
    "user_id": 804    ,"industry_id": 20 }

The response

HTTP 400 BAD REQUEST
Vary: Accept
Content-Type: text/html; charset=utf-8
Allow: GET, POST, HEAD, OPTIONS

{
    "user": [
        "This field is required."
    ]
}

Ugh. Here are the key classes from django:

class FavoriteIndustry(models.Model):
    id = models.AutoField(primary_key=True)
    user = models.ForeignKey(User, related_name='favorite_industries')
    industry = models.ForeignKey(Industry)

    class Meta:
        db_table = 'favorites_mas_industry'

class FavoriteIndustrySerializer(WithPkMixin, serializers.HyperlinkedModelSerializer):
    class Meta:
        model = myModels.FavoriteIndustry
        fields = (
            'id'
            , 'user'
            , 'industry'
        )

Edit Adding the viewset:

class FavoriteIndustriesViewSet(viewsets.ModelViewSet):
    #mixins.CreateModelMixin, viewsets.GenericViewSet):
    paginate_by = 1
    queryset = myModels\
        .FavoriteIndustry\
        .objects\
        .select_related()
    print 'SQL::FavoriteIndustriesViewSet: ' + str(queryset.query)
    serializer_class = mySerializers.FavoriteIndustrySerializer

The get/list functionality generates decent JSON:

{"count": 2, "next": "http://blah.com/rest/favorite_industries/?page=2&format=json", "previous": null, "results": [{"id": 1, "user": "http://blah.com/rest/users/804/", "industry": {"industry_id": 2, "industry_name": "Consumer Discretionary", "parent_industry_name": "Consumer Discretionary", "category_name": "Industries"}}]}

Answer 1

I have created a simplified mock up of your application.

models.py:

from django.db import models
from django.contrib.auth.models import User

class Industry(models.Model):
    name = models.CharField(max_length=128)

class FavoriteIndustry(models.Model):
    user = models.ForeignKey(User, related_name='favorite_industries')
    industry = models.ForeignKey(Industry)

views.py:

from rest_framework import viewsets
from models import FavoriteIndustry
from serializers import FavoriteIndustrySerializer

class FavoriteIndustriesViewSet(viewsets.ModelViewSet):
    queryset = FavoriteIndustry.objects.all()
    serializer_class = FavoriteIndustrySerializer

serializers.py:

from rest_framework import serializers
from models import FavoriteIndustry, Industry

class FavoriteIndustrySerializer(serializers.HyperlinkedModelSerializer):
    class Meta:
        model = FavoriteIndustry
        fields = ('id', 'user', 'industry')

urls.py:

from django.conf.urls import patterns, include, url
from core.api import FavoriteIndustriesViewSet

favorite_industries_list = FavoriteIndustriesViewSet.as_view({
    'get': 'list',
    'post': 'create'
})

urlpatterns = patterns('',
    url(r'^favorite_industries/$', favorite_industries_list, name='favorite-industries-list'),
    url(r'^users/(?P<pk>[0-9]+)/$', favorite_industries_list, name='user-detail'),
    url(r'^industries/(?P<pk>[0-9]+)/$', favorite_industries_list, name='industry-detail'),
)

And here are a few tests:

>>> 
>>> import json
>>> from django.test import Client
>>> from core.models import Industry
>>> 
>>> industry = Industry(name='candy')
>>> industry.save()
>>> 
>>> c = Client()
>>> 
>>> response = c.get('http://localhost:8000/favorite_industries/')
>>> response.content
'[]'
>>> 
>>> data = {
...     'user': 'http://localhost:8000/users/1/',
...     'industry': 'http://localhost:8000/industries/1/'
... }
>>> 
>>> response = c.post('http://localhost:8000/favorite_industries/', json.dumps(data), 'application/json')
>>> response.content
'{"id": 1, "user": "http://testserver/users/1/", "industry": "http://testserver/industries/1/"}'
>>> 
>>> response = c.get('http://localhost:8000/favorite_industries/')
>>> response.content
'[{"id": 1, "user": "http://testserver/users/1/", "industry": "http://testserver/industries/1/"}]'
>>> 

Django REST Framework expects user and industry fields as URLs rather than ids since you are using HyperlinkedModelSerializer.

---

Using IDs

In case you need to use object ids instead of URLs, use ModelSerializer instead of HyperlinkedModelSerializer and pass ids to user and industry:

serializers.py:

from rest_framework import serializers
from models import FavoriteIndustry, Industry

class FavoriteIndustrySerializer(serializers.ModelSerializer):
    class Meta:
        model = FavoriteIndustry
        fields = ('id', 'user', 'industry')

And tests:

>>> 
>>> import json
>>> from django.test import Client
>>> from core.models import Industry
>>> 
>>> #industry = Industry(name='candy')
>>> #industry.save()
>>> 
>>> c = Client()
>>> 
>>> response = c.get('http://localhost:8000/favorite_industries/')
>>> response.content
'[{"id": 1, "user": 1, "industry": 1}, {"id": 2, "user": 1, "industry": 1}]'
>>> 
>>> data = {
...     'user': 1,
...     'industry': 1
... }
>>> 
>>> response = c.post('http://localhost:8000/favorite_industries/', json.dumps(data), 'application/json')
>>> response.content
'{"id": 3, "user": 1, "industry": 1}'
>>> 
>>> response = c.get('http://localhost:8000/favorite_industries/')
>>> response.content
'[{"id": 1, "user": 1, "industry": 1}, {"id": 2, "user": 1, "industry": 1}, {"id": 3, "user": 1, "industry": 1}]'
>>> 

Answer 2

This will do it. But I think the django-rest-framework should provide this plumbing for me, so please follow up with any better answers

class FavoriteIndustriesViewSet(mixins.ListModelMixin, viewsets.GenericViewSet):
    paginate_by = 1
    queryset = myModels\
        .FavoriteIndustry\
        .objects\
        .select_related()
    print 'SQL::FavoriteIndustriesViewSet: ' + str(queryset.query)
    serializer_class = mySerializers.FavoriteIndustrySerializer

    def create(self, request):
        print(request.DATA)
        user_id = request.DATA['user_id']
        industry_id = request.DATA['industry_id']
        favorite = myModels.FavoriteIndustry(user_id=user_id, industry_id=industry_id)
        favorite.save()
        responseData = {
            'user_id': user_id
            , 'industry_id': industry_id
            , 'message': 'FavoriteIndustry saved.'
        }
        return Response(responseData)