Consider this useless serializer:

class MySerializer(serializers.Serializer):

    random_number = serializers.SerializerMethodField()

    def get_random_number(self):
        # Chosen by fair dice roll.
        # Guaranteed to be random.
        return 4

Assuming you added this serializer in an endpoint and generated the OpenAPI schema, the serializer would look like this:

properties:
  random_number:
    type: string
  required:
  - random_number

The issue here is there is no way to tell DRF to use type: number here. I thought of a few possibilities:

• An output_field attribute, like serializers.SerializerMethodField(output_field=serializers.IntegerField()), similarly to Django's Query Expressions

• A decorator, like openapi_type(serializers.SerializerMethodField(), serializers.IntegerField())

• An attribute, similarly to setting descriptions on admin actions:

  random_number = serializers.SerializerMethodField()
  
  def get_random_number(self):
      return 4
  
  get_random_number.output_field = serializers.IntegerField()

• Simply something DRF does not support, which probably should be documented somewhere as a possible caveat.