6
When passing data to a serializer instance, the unmodified data will be made available as .initial_data. If the data keyword argument is not passed then the .initial_data attribute will not exist.
serializer = MyFooSerializer(data={'foo':'bar'})
print(serializer.initial_data) # this will print {'foo':'bar'}The request.data returns the parsed content of the request body.
3
Requests.data contains the data that comes in from the frontend. Arguably, you should leave requests.data alone and use a serializer to convert said data into more complex types. The use cases for serializers are pretty vast ranging, but the most common is translation of data into database model instances.
Source:stackexchange.com