Custom Fields

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The most common way to create a custom field with drf_serpy is to override drf_serpy.Field.to_value. This method is called on the value retrieved from the object being serialized. For example, to create a field that adds 5 to every value it serializes, do:

   class Add5Field(drf_serpy.Field):
      def to_value(self, value):
         return value + 5

Then to use it:

   class Obj(object):
      pass

   class ObjSerializer(drf_serpy.Serializer):
      foo = Add5Field()

   f = Obj()
   f.foo = 9
   ObjSerializer(f).data
   # {'foo': 14}

Another use for custom fields is data validation. For example, to validate that every serialized value has a '.' in it:

   class ValidateDotField(drf_serpy.Field):
      def to_value(self, value):
         if '.' not in value:
            raise ValidationError('no dot!')
         return value

For more control over the behavior of the field, override drf_serpy.Field.as_getter. When the drf_serpy.Serializer class is created, each field will be compiled to a getter, that will be called to get its associated attribute from the object. For an example of this, see the drf_serpy.MethodField implementation.