Proper Usage Of "callable Default Function" In Django Rest Framework (drf)

Question: How can I access the serializer instance or any relevant arguments in the default callable function of DRF field? Scenario: I have a serializer configuration as below, d

Solution 1:

Update For DRF>=3.12, use this king of default class

classDefaultBarValue:
    requires_context = True

    def __call__(self, serializer_instance):
        if serializer_instance.context['request'].method == 'GET':
            return'return value One'return'return value Two'

---

pass a class instance instead of function to the default argument

# default callable classclassDefaultBarValue:
    """
    "Method `set_context` on defaults is deprecated and will
    no longer be called starting with 3.12. Instead set
    `requires_context = True` on the class, and accept the
    context as an additional argument.
    """
    requires_context = True# for DRF>=3.12
    serializer_instance = None# not required for DRF>=3.12defset_context(self, serializer_instance): # not required for DRF>=3.12
        self.serializer_instance = serializer_instance

    def__call__(self, serializer_instance=None):
        if serializer_instance isNone:  # will be None for older versions of DRFif self.serializer_instance.context['request'].method == 'GET':
                return'return value One'return'return value Two'else:  # for DRF>=3.12if serializer_instance.context['request'].method == 'GET':
                return'return value One'return'return value Two'

# serializerclass FooSerializer(serializers.Serializer):
    bar = serializers.CharField(source='foo.bar', default=DefaultBarValue())