title: ReturnDict object not callable Django Rest Framework
body: <p>I am new to both SO and Django DRF. 
  Whenever I try running the code. I get the error "TypeError ReturnDict object not callable". </p>
  
  <p>models.py  </p>
  
  <pre><code>from __future__ import unicode_literals
  
  from django.db import models
  
  # Create your models here.
  
  class Fish(models.Model):
      name=models.CharField(max_length=120)
      created=models.DateTimeField(auto_now_add=True)
      active = models.BooleanField()
  </code></pre>
  
  <p>serializers.py</p>
  
  <pre><code>from  fishes.models import  Fish
  from  rest_framework import  serializers
  
  class FishSerializers(serializers.ModelSerializer):
      success=serializers.SerializerMethodField('is_successful')
  
  
  
      def is_successful(self,obj):
          return self.context.get('value')
  
      class Meta:
          model=Fish
          fields=('name', 'active', 'created','success')
  </code></pre>
  
  <p>views.py</p>
  
  <pre><code>from django.shortcuts import render
  from  rest_framework import viewsets
  from rest_framework import permissions
  from  fishes.serializers import FishSerializers
  from fishes.models import  Fish
  # Create your views here.
  
  class FishViewSets(viewsets.ModelViewSet):
      queryset = Fish.objects.get(id=2)
      serializer_class = FishSerializers(queryset,context={'value':'brother'}).data
  </code></pre>
  
  <p>urls.py</p>
  
  <pre><code>from django.conf.urls import url,include
  from django.contrib import admin
  from rest_framework import  routers
  from fishes import  views
  
  router= routers.DefaultRouter()
  router.register(r'api/fishes',views.FishViewSets,base_name='FishViewSets')
  urlpatterns = [
      url(r'^admin/', admin.site.urls),
      url(r'^',include(router.urls)),
      url(r'^api-auth/', include('rest_framework.urls', namespace='rest_framework'))
  ]
  </code></pre>
  
  <p>error_trace</p>
  
  <pre><code>Traceback (most recent call last):
    File "/usr/local/lib/python2.7/dist-packages/django/core/handlers/base.py", line 149, in get_response
      response = self.process_exception_by_middleware(e, request)
    File "/usr/local/lib/python2.7/dist-packages/django/core/handlers/base.py", line 147, in get_response
      response = wrapped_callback(request, *callback_args, **callback_kwargs)
    File "/usr/local/lib/python2.7/dist-packages/django/views/decorators/csrf.py", line 58, in wrapped_view
      return view_func(*args, **kwargs)
    File "/usr/local/lib/python2.7/dist-packages/rest_framework/viewsets.py", line 87, in view
      return self.dispatch(request, *args, **kwargs)
    File "/usr/local/lib/python2.7/dist-packages/rest_framework/views.py", line 466, in dispatch
      response = self.handle_exception(exc)
    File "/usr/local/lib/python2.7/dist-packages/rest_framework/views.py", line 463, in dispatch
      response = handler(request, *args, **kwargs)
    File "/usr/local/lib/python2.7/dist-packages/rest_framework/mixins.py", line 47, in list
      serializer = self.get_serializer(queryset, many=True)
    File "/usr/local/lib/python2.7/dist-packages/rest_framework/generics.py", line 111, in get_serializer
      return serializer_class(*args, **kwargs)
  TypeError: 'ReturnDict' object is not callable
  </code></pre>
  
  <p>Please help to understand and resolve this error in django rest framework!</p>