DRF Flat Errors Response

flat_errors_response.py

"""
Monkey patch for Response class in Django REST Framework. 
Original response's data will be accessible by key "data" 
and errors have flat format, so it is easier to handle 
errors on client side.
"""


from django.utils import six
from rest_framework.response import Response
from rest_framework.serializers import Serializer


def get_data(data, status_code):

    if status_code < 400:
        return {
            'data': data,
            'success': True,
            'errors': [],
        }

    errors = []

    if not isinstance(data, dict) or not data:
        errors.append({'field': None, 'message': 'Not described error'})
    else:
        for key, error in data.items():
            if key in ('non_field_errors', 'detail'):
                key = None
            if isinstance(error, str):  # for status code in range [401, 500]
                errors.append({'field': key, 'message': error})
            elif isinstance(error, list):  # for status code 400
                for e in error:
                    if isinstance(e, str):
                        errors.append({'field': key, 'message': e})
                    else:
                        errors.append({'field': None, 'message': 'Unknown error'})
            else:
                errors.append({'field': None, 'message': 'Unknown error'})

    return {
        'data': {},
        'success': False,
        'errors': errors,
    }


def __init__(self, data=None, status=None,
             template_name=None, headers=None,
             exception=False, content_type=None):

    super(Response, self).__init__(None, status=status)

    if isinstance(data, Serializer):
        msg = (
            'You passed a Serializer instance as data, but '
            'probably meant to pass serialized `.data` or '
            '`.error`. representation.'
        )
        raise AssertionError(msg)

    self.data = get_data(data, self.status_code)
    self.template_name = template_name
    self.exception = exception
    self.content_type = content_type

    if headers:
        for name, value in six.iteritems(headers):
            self[name] = value

Response.__init__ = __init__