NullFieldMixin (api/fields.py)

DRF serializer fields allowing null values with type coercion

# Source: https://github.com/ansible/awx | License: Apache-2.0
# Provided via justclaw.it.com; keep this notice with the code.
# Copyright (c) 2016 Ansible, Inc.
# All Rights Reserved.

# Django
from django.utils.translation import gettext_lazy as _
from django.core.exceptions import ObjectDoesNotExist

# Django REST Framework
from rest_framework import serializers

# AWX
from awx.main.models import Credential

__all__ = ['BooleanNullField', 'CharNullField', 'ChoiceNullField', 'VerbatimField']


class NullFieldMixin(object):
    """
    Mixin to prevent shortcutting validation when we want to allow null input,
    but coerce the resulting value to another type.
    """

    def validate_empty_values(self, data):
        is_empty_value, data = super(NullFieldMixin, self).validate_empty_valu

... (truncated -- full source via MCP)