A better approach would be to define a hidden field say, my_hidden_field = serializer.HiddenField(default=None) in the Serializer class whose value can be obtained in following ways:

• Passed during instance creation, eg. `serializer = MySerializer(my_hidden_field=val)
• Define a validate_my_hidden_field for it and derive its value based on context.
• If its value depends on other fields, then use validate method to derive its value and assign to it.