initial_data
serializer = serializer클래스(data=request.data)
seirlaizer.initial_data('필드') = 값
validated_data
serializer = serializer클래스(data=request.data)
if serializer.is_valid():
serializer.validated_data['필드'] = 값
serializer.save()
data
serializer = serializer클래스(data=request.data)
if serializer.is_valid():
serializer.save()
serializer.data['필드']