transaction.py

from django.db import transaction
from django.http import HttpResponse


class RollbackAndReport(Exception):
    def __init__(self, error_json_report):
        self.error_json_report = error_json_report

    def __str__(self):
        return self.error_json_report


def reportable_commit_on_success(f):

    @transaction.commit_manually
    def decorated_function(*args, **kwargs):
        try:
            result = f(*args, **kwargs)
        except RollbackAndReport as e:
            transaction.rollback()
            return HttpResponse(e.error_json_report)
        except:
            transaction.rollback()
            raise
        else:
            try:
                transaction.commit()
                return result
            except:
                transaction.rollback()
                raise

    return decorated_function


def test_report_error(self):
    @reportable_commit_on_success
    def insert_user():
        User(name='matri', pwd='boop', longname='Matthieu Ricard').save()
        raise RollbackAndReport(json.dumps({'error': 'catch me if you can'}))
        return HttpResponse(json.dumps({'should not': 'return this'}))

    User.objects.all().delete()
    response = insert_user()
    parsed_response = json.loads(response.content)
    expected_result = {'error': 'catch me if you can'}
    self.assertEqual(response.status_code, 200)
    self.assertEqual(expected_result, parsed_response)
    self.assertEqual(0, User.objects.all().count())