title: Django rest framework add more data when serialize many object
body: <p>I would like to add an additional field for user's details. But it has to use another value outside of database fields.
  For more clearly like this</p>
  
  <p><strong>model:</strong></p>
  
  <pre><code>class User(models.Model):
      id= models.AutoField(primary_key=True)
      last_name= models.CharField(max_length=20)
      first_name=models.CharField(max_length=20)
      role_id = models.IntegerField()
  </code></pre>
  
  <p><strong>serializer:</strong></p>
  
  <pre><code>class UserSerializer(serializers.ModelSerializer):
      display_summary = serializers.SerializerMethodField()
      login_user_id = serializers.IntegerField(required=False)
  
      class Meta:
          model = User
          fields = ("id","last_name","first_name", "display_summary", "login_user_id")
  
      def get_display_summary(self, obj):
          login_id    = self.validated_data.get('login_user_id', None)
          login_user  = User.objects.filter(pk=login_id).first()
          if obj.role_id==2 and login_user.role_id==1:
              return 1
  
          return 0
  </code></pre>
  
  <p>So in my views, when getting just one user, it's all ok:</p>
  
  <pre><code>@api_view(['GET'])
  @login_required
  def get_user(request, login_user, user_id):
      serializer = UserSerializer(User.objects.get(pk=user_id), data={'login_user_id': login_user.id})
      if serializer.is_valid():
          result = serializer.data
          return Response(result, status=status.HTTP_200_OK)
  
  #result:
  #{
  #    "id": 2,
  #    "last_name": "V",
  #    "first_name": "Lich",
  #    "role_id": 2,
  #    "display_summary": 1
  #}
  </code></pre>
  
  <p>But when I need to return a list, how can I add additional data (login_user_id)?
  This is not working:</p>
  
  <pre><code>users = User.objects.filter(last_name__icontains='v')
  result_serializer = UserSerializer(users, data={'login_user_id': login_user.id}, many=True)
  return result_serializer.data
  </code></pre>
  
  <p>The error occur say that it's looking for a list, not a dict for inputted param.</p>