[Fixed]-Django rest framework model serializers – read nested, write flat

Thanks to previous posts, I went with a similar solution based off get_serializer_class for this.

I also wanted to be able to change the serializer class depending on method.

First, I added an attribute to the view class with a dictionary mapping request methods to serializer classes.

 serializer_classes = {
     'GET': NestedSerializer,
     'POST': FlatSerializer
 }

Then, I defined a mixin to use where I want this behavior.

class SwappableSerializerMixin(object):
    def get_serializer_class(self):
        try:
            return self.serializer_classes[self.request.method]
        except AttributeError:
            logger.debug('%(cls)s does not have the required serializer_classes'
                         'property' % {'cls': self.__class__.__name__})
            raise AttributeError
        except KeyError:
            logger.debug('request method %(method)s is not listed'
                         ' in %(cls)s serializer_classes' %
                         {'cls': self.__class__.__name__,
                          'method': self.request.method})
            # required if you don't include all the methods (option, etc) in your serializer_class
            return super(SwappableSerializerMixin, self).get_serializer_class() es

I had the same problem and it looks like quite a few others have it too. Carlton Gibson answer actually lead me to my hacky solution. I ended up using a ModelSerializer with the depth set and created the following mixin to use in the views.

class ReadNestedWriteFlatMixin(object):
    """
    Mixin that sets the depth of the serializer to 0 (flat) for writing operations.
    For all other operations it keeps the depth specified in the serializer_class
    """
    def get_serializer_class(self, *args, **kwargs):
        serializer_class = super(ReadNestedWriteFlatMixin, self).get_serializer_class(*args, **kwargs)
        if self.request.method in ['PATCH', 'POST', 'PUT']:
            serializer_class.Meta.depth = 0
        return serializer_class

The simplest thing that occurs to me is to override get_serializer_class() on your view for POST/PUT to return a modified serializer not specifying the depth parameter and using a PrimaryKeyRelatedField for your languages field.