Where does the self.get_serializer method come from in the Django REST Framework?

Question

In the DRF source code, there's a get_serializer method. It wasn't inherited from object and it's not a method in the CreateModelMixin class. Where does this method come from?

serializer = self.get_serializer(data=request.data) 

Here's the larger chunk of code for context.

from __future__ import unicode_literals  from rest_framework import status from rest_framework.response import Response from rest_framework.settings import api_settings   class CreateModelMixin(object):     """     Create a model instance.     """     def create(self, request, *args, **kwargs):         serializer = self.get_serializer(data=request.data)         serializer.is_valid(raise_exception=True)         self.perform_create(serializer)         headers = self.get_success_headers(serializer.data)         return Response(serializer.data, status=status.HTTP_201_CREATED, headers=headers)      def perform_create(self, serializer):         serializer.save()      def get_success_headers(self, data):         try:             return {'Location': data[api_settings.URL_FIELD_NAME]}         except (TypeError, KeyError):             return {} 

There are a few SO posts that that also use this method. Like this, this, and this. But I still can't figure out where the implementation is.

Answer 1

CreateModelMixin along with all other mixin classes (Eg. ListModelMixin, UpdateModelMixin etc) are defined in rest_framework/mixins.py file.

These mixin classes provide all the basic CRUD operations on a model. You just need to define a serializer_class and queryset in your generic view to perform all these operations. DRF has separated out these common functionality in separate mixin classes so that they can be injected/mixed-in in a view and used as and when required.

In the DRF source code, there's a get_serializer method. It wasn't inherited from object and it's not a method in the CreateModelMixin class. Where does this method come from?

In the GenericAPIView, get_serializer method is defined. The combination of different mixin classes along with GenericAPIView class provide us different generic views for different use cases.

class GenericAPIView(views.APIView):     """     Base class for all other generic views.     """      def get_serializer(self, *args, **kwargs):         """         Return the serializer instance that should be used for validating and         deserializing input, and for serializing output.         """         serializer_class = self.get_serializer_class()         kwargs['context'] = self.get_serializer_context()         return serializer_class(*args, **kwargs) 

Other generic views then inherit the relevant mixin along with GenericAPIView.

Eg. CreateAPIView inherit the CreateModelMixin along with GenericAPIView to provide create-only endpoints.

# rest_framework/generics.py class CreateAPIView(mixins.CreateModelMixin,                     GenericAPIView):     ...