title: Django Rest Framework File Upload Says Document Not Submitted
body: <p>When I upload a file through requests module it says no document submitted</p>
  
  <p><em>models.py</em>:</p>
  
  <pre><code>class Apidocument(models.Model):
      iden = models.CharField(max_length=255)
      document = models.FileField(upload_to='media/documents')
      uploaded_at = models.DateTimeField(auto_now_add=True)
  </code></pre>
  
  <p><em>serializer.py</em>:</p>
  
  <pre><code>class DataSerializer(serializers.ModelSerializer):
      document = serializers.FileField(max_length=None,use_url =True)
      class Meta():
          model = Apidocument
          fields = ('uploaded_at','document')
  </code></pre>
  
  <p><em>views.py</em>:</p>
  
  <pre><code>class ApiViewSet(viewsets.ModelViewSet):
      queryset = Apidocument.objects.all().order_by('-uploaded_at')
      serializer_class = DataSerializer
  
  
  files = {"file": ('b839', open('/home/user/b839.jpeg', 'rb'), 'multipart/form-data')}
  resp = requests.post('http://localhost:8000/api/upload/', files=files)
  </code></pre>