Category: Geek

A Django project I’m working on defines two databases in its config: The standard/default internal db as well as a remote legacy read-only database belonging to my organization. Models for the read-only db were generated by inspectdb, and naturally have managed = False in their Meta class, which prevents Django from attempting any form of migration on them.

Unfortunately, that also prevents the Django test runner from trying to create a schema mirror of it during test runs. But what if you want to stub out some sample data from the read-only database into a fixture that can be loaded and accessed during unit tests? You’ll need to do the following:

• Tell Django to create the second test database locally rather than on the remote host
• Disable any routers you have that route queries for certain models through the remote db
• Tell Django to override the Managed = False attribute in the Meta class during the test run

Putting that all together turned out to be a bit tricky, but it’s not bad once you understand how and why you need to take these steps. Because you’ll need to override a few settings during test runs only, it makes sense to create a separate test_settings.py to keep everything together:

from project.local_settings import *
from django.test.runner import DiscoverRunner


class UnManagedModelTestRunner(DiscoverRunner):
    '''
    Test runner that automatically makes all unmanaged models in your Django
    project managed for the duration of the test run.
    Many thanks to the Caktus Group: http://bit.ly/1N8TcHW
    '''

    def setup_test_environment(self, *args, **kwargs):
        from django.db.models.loading import get_models
        self.unmanaged_models = [m for m in get_models() if not m._meta.managed]
        for m in self.unmanaged_models:
            m._meta.managed = True
        super(UnManagedModelTestRunner, self).setup_test_environment(*args, **kwargs)

    def teardown_test_environment(self, *args, **kwargs):
        super(UnManagedModelTestRunner, self).teardown_test_environment(*args, **kwargs)
        # reset unmanaged models
        for m in self.unmanaged_models:
            m._meta.managed = False

# Since we can't create a test db on the read-only host, and we
# want our test dbs created with postgres rather than the default, override
# some of the global db settings, only to be in effect when "test" is present
# in the command line arguments:

if 'test' in sys.argv or 'test_coverage' in sys.argv:  # Covers regular testing and django-coverage

    DATABASES['default']['ENGINE'] = 'django.db.backends.postgresql_psycopg2'
    DATABASES['default']['HOST'] = '127.0.0.1'
    DATABASES['default']['USER'] = 'username'
    DATABASES['default']['PASSWORD'] = 'secret'

    DATABASES['tmi']['ENGINE'] = 'django.db.backends.postgresql_psycopg2'
    DATABASES['tmi']['HOST'] = '127.0.0.1'
    DATABASES['tmi']['USER'] = 'username'
    DATABASES['tmi']['PASSWORD'] = 'secret'


# The custom routers we're using to route certain ORM queries
# to the remote host conflict with our overridden db settings.
# Set DATABASE_ROUTERS to an empty list to return to the defaults
# during the test run.

DATABASE_ROUTERS = []

# Set Django's test runner to the custom class defined above
TEST_RUNNER = 'project.test_settings.UnManagedModelTestRunner'

With that in place, you can now run your tests with:

./manage.py test --settings=project.test_settings

… leaving settings untouched during normal site operations. You can now serialize some data from your read-only host and load it as a fixture in your tests:

class DirappTests(TestCase):

    # Load test data into both dbs:
    fixtures = ['auth_group.json', 'sample_people.json']

    ...

    def test_stub_data(self):
        # Guarantees that our sample data is being loaded in the test suite
        person = Foo.objects.get(id=7000533)
        self.assertEqual(person.first_name, "Quillen")

Of the several libraries/packages available for setting up social network logins for Django projects, I currently find django-allauth the most complete, with the best docs and the most active development. Doesn’t hurt that the lead dev on the project is super friendly and responsive on StackOverflow!

But not everything about it is intuitive. After wiring up Twitter, Facebook and Google as login providers, I found that first and last names were not being retrieved from the remote services when an account was successfully created. I also, frustratingly, could find only the most oblique references online to how to accomplish this.

There are a couple of ways to go about it – you can either receive and handle the allauth.account.signals.user_signed_up signal that allauth emits on success, or set up allauth.socialaccount.adapter.DefaultSocialAccountAdapter, which is also unfortunately barely documented.

I decided to go the signals route. The key to making this work is in intercepting the sociallogin parameter your signal handler will receive when an account is successfully created. I then installed a breakpoint with import pdb; pdb.set_trace() to inspect the contents of sociallogin. Once I had access to those goodies, I was able to post-populate the corresponding User objects in the database.

This sample code grabs First/Last names from Twitter, Facebook or Google; season to taste:

# When account is created via social, fire django-allauth signal to populate Django User record.
from allauth.account.signals import user_signed_up
from django.dispatch import receiver

@receiver(user_signed_up)
def user_signed_up_(request, user, sociallogin=None, **kwargs):
    '''
    When a social account is created successfully and this signal is received,
    django-allauth passes in the sociallogin param, giving access to metadata on the remote account, e.g.:

    sociallogin.account.provider  # e.g. 'twitter' 
    sociallogin.account.get_avatar_url()
    sociallogin.account.get_profile_url()
    sociallogin.account.extra_data['screen_name']

    See the socialaccount_socialaccount table for more in the 'extra_data' field.
    '''

    if sociallogin:
        # Extract first / last names from social nets and store on User record
        if sociallogin.account.provider == 'twitter':
            name = sociallogin.account.extra_data['name']
            user.first_name = name.split()[0]
            user.last_name = name.split()[1]

        if sociallogin.account.provider == 'facebook':
            user.first_name = sociallogin.account.extra_data['first_name']
            user.last_name = sociallogin.account.extra_data['last_name']

        if sociallogin.account.provider == 'google':
            user.first_name = sociallogin.account.extra_data['given_name']
            user.last_name = sociallogin.account.extra_data['family_name']

        user.save()