title: Django Rest Framework list missing records
body: <p>I have set up a Django Rest Framework (v.1.11.7) Viewset called CustomerViewset. It's as simple as follows:</p>
  
  <pre><code>class CustomerViewSet(viewsets.ModelViewSet):
    queryset = Customer.objects.all()
    serializer_class = CustomerSerializer
  </code></pre>
  
  <p>The serializer looks like:</p>
  
  <pre><code>class CustomerSerializer(serializers.ModelSerializer):
    class Meta:
      model = Customer
      fields = ('id', 'name', 'zone', 'website', 'email', 'slug', 'active', 'description', 'primary_color', 'nif', 'country', 'city', 'zip_code', 'address_1', 'address_2', 'address_3', 'telephone', 'allow_delete')
  </code></pre>
  
  <p>And the model:</p>
  
  <pre><code>class Customer(models.Model):
    name = models.CharField(
      max_length=256
    )
    zone = models.ForeignKey(
      Zone,
      null=True,
      blank=True
    )
    active = models.BooleanField(
      default=True
    )
    allow_delete = models.BooleanField(
      default=True
    )
    logo = models.ImageField(
      null=True,
      blank=True,
      upload_to="customer/logo"
    )
    description = models.TextField(
      blank=True
    )
    website = models.URLField(
      blank=True
    )
    email = models.EmailField(
      blank=True
    )
    telephone = models.CharField(
      max_length=256,
      null=True,
      blank=True
    )
    slug = models.SlugField(unique=True, blank=True, null=True)
    nif = models.CharField(max_length=32, null=True, blank=True)
    country = models.CharField(max_length=128, null=True, blank=True)
    city = models.CharField(max_length=128, null=True, blank=True)
    zip_code = models.CharField(max_length=128, null=True, blank=True)
    address_1 = models.CharField(max_length=256, null=True, blank=True)
    address_2 = models.CharField(max_length=256, null=True, blank=True)
    address_3 = models.CharField(max_length=256, null=True, blank=True)
    primary_color = models.CharField(max_length=7, default="#F8F9FA")
  </code></pre>
  
  <p>This should work with no problem, however after a change (update or partial-update) is made to a Customer object, the particular object that was updated won't be listed again. The update payload that causes the trouble has the next structure:</p>
  
  <pre><code>active  true
  address_1   null
  address_2   null
  address_3   null
  allow_delete    true
  city    null
  country null
  description 
  email   
  id  818
  name    'Name test'
  nif null
  primary_color   '#F8F9FA'
  slug    'name-test'
  telephone   null
  website 
  zip_code    null
  zone    1
  </code></pre>
  
  <p>Not even restarting the server (caché issues). But it still can be retrieved. No errors displayed on console or logs; it simply ignores the record when listing.</p>
  
  <p>By overriding the <code>get_queryset</code> of the Viewset I can do the following:</p>
  
  <pre><code>    def get_queryset(self):
        queryset = Customer.objects.all()
        c = Customer.objects.get(id=818)
        print(c)
        _c = queryset.filter(id=818)
        print(_c)
        return queryset
  </code></pre>
  
  <p>818 is the id of the updated record. It does find the by filtering against  both, the queryset and the Customer model. But still, it's not on the list!</p>
  
  <p>This is really weird and don't know what I'm missing here. Any idea would be appreciated.</p>