Mongo related issue in Django

[Ashish Khatkar]

Hi,

Today I was trying to do user authentication with Django + MongoDB. I was constantly getting "Metadict object has no attribute pk" error. I searched for the fix but nothing helped. In the end, I read the implementation of login function and changed request.session[SESSION_KEY] = user._meta.pk.value_to_string(user) to request.session[SESSION_KEY] = user.id in django/contrib/auth/__init__.py and correspondingly changed return int(value) line no 947 to return value in django/db/models/fields/__init__.py as automated primary key for mongo db is a hexadecimal string. It worked this way.

Is there any other way to achieve same thing ? If not should I create a PR to fix this.

[Tim Graham]

It's difficult to tell what the issue is without seeing all you code, but "is this is a bug?" questions are more suited for the django-users mailing list. A good first step in testing your "fix" is to see if Django's test suite passes afterwards. I suspect you'll see some test failures with the changes you proposed.

[Ashish Khatkar]

Hi,

This is my settings.py

"""

Django settings for testApp project.

Generated by 'django-admin startproject' using Django 1.8.2.

For more information on this file, see

https://docs.djangoproject.com/en/1.8/topics/settings/

For the full list of settings and their values, see

https://docs.djangoproject.com/en/1.8/ref/settings/

"""

# Build paths inside the project like this: os.path.join(BASE_DIR, ...)

import os

BASE_DIR = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))

# Quick-start development settings - unsuitable for production

# See https://docs.djangoproject.com/en/1.8/howto/deployment/checklist/

# SECURITY WARNING: keep the secret key used in production secret!

SECRET_KEY = ')s&uno-o3x)v^1-2bjt4o8*(sf^8zw42+#tvm(&km&fs+39x!5'

# SECURITY WARNING: don't run with debug turned on in production!

DEBUG = True

ALLOWED_HOSTS = ["localhost"]

# Application definition

INSTALLED_APPS = (

   'django.contrib.admin',

   'django.contrib.auth',

   'django.contrib.contenttypes',

   'django.contrib.sessions',

   'django.contrib.messages',

   'django.contrib.staticfiles',

   'meriApp',

)

MIDDLEWARE_CLASSES = (

   'django.contrib.sessions.middleware.SessionMiddleware',

   'django.middleware.common.CommonMiddleware',

   'django.middleware.csrf.CsrfViewMiddleware',

   'django.contrib.auth.middleware.AuthenticationMiddleware',

   'django.contrib.auth.middleware.SessionAuthenticationMiddleware',

   'django.contrib.messages.middleware.MessageMiddleware',

   'django.middleware.clickjacking.XFrameOptionsMiddleware',

   'django.middleware.security.SecurityMiddleware',

)

ROOT_URLCONF = 'testApp.urls'

TEMPLATES = [

   {

       'BACKEND': 'django.template.backends.django.DjangoTemplates',

       'DIRS': [],

       'APP_DIRS': True,

       'OPTIONS': {

           'context_processors': [

               'django.template.context_processors.debug',

               'django.template.context_processors.request',

               'django.contrib.auth.context_processors.auth',

               'django.contrib.messages.context_processors.messages',

           ],

       },

   },

]

WSGI_APPLICATION = 'testApp.wsgi.application'

# Database

# https://docs.djangoproject.com/en/1.8/ref/settings/#databases

# DATABASES = {

#     'default': {

#         'ENGINE': 'django.db.backends.sqlite3',

#         'NAME': os.path.join(BASE_DIR, 'db.sqlite3'),

#     }

# }

# Internationalization

# https://docs.djangoproject.com/en/1.8/topics/i18n/

LANGUAGE_CODE = 'en-us'

TIME_ZONE = 'Asia/Kolkata'

USE_I18N = True

USE_L10N = True

USE_TZ = True

# Static files (CSS, JavaScript, Images)

# https://docs.djangoproject.com/en/1.8/howto/static-files/

STATIC_URL = '/static/'

LOGIN_URL = ''

LOGIN_REDIRECT_URL = '/meriApp/'

import mongoengine

DATABASES = {

   'default': {

       'ENGINE': 'django.db.backends.dummy',

   },

}

SESSION_ENGINE = 'mongoengine.django.sessions' # optional

# _MONGODB_USER = ''

# _MONGODB_PASSWD = ''

# _MONGODB_HOST = ''

_MONGODB_NAME = 'test'

# _MONGODB_DATABASE_HOST = \

#     'mongodb://%s:%s@%s/%s' \

#     % (_MONGODB_USER, _MONGODB_PASSWD, _MONGODB_HOST, _MONGODB_NAME)

# mongoengine.connect(_MONGODB_NAME, host=_MONGODB_DATABASE_HOST)

mongoengine.connect(_MONGODB_NAME)

AUTHENTICATION_BACKENDS = (

   'mongoengine.django.auth.MongoEngineBackend',

)

This is the view with which I am authenticating :

@csrf_protect

def login_view(request):

  if request.method == 'GET':

            return render_to_response('index.html', context_instance=RequestContext(request))

      elif request.method == 'POST':

         try:

                   username = request.POST['email']

                       password = request.POST['password']

                    user = User.objects.get(username=username)

                     if user.check_password(password):

                              user.backend = 'mongoengine.django.auth.MongoEngineBackend'

                            user = authenticate(username=username, password=password)

                                login(request, user)

                           return HttpResponseRedirect('/meriApp/dashboard')

                      else:

                          return render_to_response('index.html', {'msg' : "Invalid Email/Password"}, context_instance=RequestContext(request))

          except DoesNotExist:

                   return render_to_response('index.html', {'msg' : "This user doesn't exist"}, context_instance=RequestContext(request))

Changes I did in django/contrib/auth/__init__.py

try:

           return int(value)

       except ValueError:

           return value

       except TypeError:

           raise exceptions.ValidationError(

               self.error_messages['invalid'],

               code='invalid',

               params={'value': value},

           )

Changes I did in django/db/models/fields/__init__.py

try:

       request.session[SESSION_KEY] = user._meta.pk.value_to_string(user)

   except Exception:

       request.session[SESSION_KEY] = user.id

Now if I don't perform these changes, I get metadict object has no attribute pk. Which i resolved by adding try except. Similarly to resolve validation error i added try except block there.

[Tim Graham]

Sorry, but that doesn't help as I have no experience with mongoengine. As I said, if you want further help, you might find it on the django-users mailing list but I would  check mongoengine support for Django. It's not so clear they are working on it now.

https://github.com/MongoEngine/mongoengine/blob/master/docs/django.rst

On Tuesday, June 23, 2015 at 2:53:45 PM UTC-4, Ashish Khatkar wrote:

Hi,

...

[Ashish Khatkar]

Sure, I will ask this question in Django users also. Though I ran the test suite after fixing this and all tests passed without any error.