Add docs: how to use migrations on dango>1.7 with a custom application

[synasius]

When using a custom application model migrations don't work out of the box.
The makemigrations command should fail with an error like:

ValueError: Lookup failed for model referenced by field oauth2_provider.Grant.application: foo.MyApp 

Let's say you have your custom user model in foo.MyApp, follow these steps to correctly create migrations for your app:

1. Check you DON'T have OAUTH2_PROVIDER_APPLICATION_MODEL in your settings or it is commented out.
2. Check both oauth2_provider and foo are listed in INSTALLED_APPS.
3. Run makemigrations command
4. Now add or uncomment OAUTH2_PROVIDER_APPLICATION_MODEL\
5. Run migrate command.

[dustinfarris]

Is this for someone who is a first-time user, or someone upgrading from Django < 1.7, or someone upgrading from DOT < 0.8?

[synasius]

You can reproduce the error with django>=1.7 and the current DOT master branch.

Create a new project, add an app with the custom application model and set the OAUTH2_PROVIDER_APPLICATION_MODEL in the settings.
Then try to run makemigrations and you'll get the error.

The steps above are the only workaround I'm aware of.

[femesq]

@synasius Is the equivalent process necessary for those still using Django 1.6+South, or this issue is Django Migration (>1.7) issue?

[synasius]

the issue occurs on a new Django>=1.7 project when using a custom application model.

Please note that changing the Application Model has the same effect of changing user model, so the same warnings applies. Please read https://docs.djangoproject.com/en/1.8/topics/auth/customizing/#substituting-a-custom-user-model carefully!!

[mitchellrj]

It may be useful for people adding Django-OAuth-Toolkit to an existing project to be aware of run_before:

https://docs.djangoproject.com/en/1.9/howto/writing-migrations/#controlling-the-order-of-migrations

Any migration that adds a swappable application model should have:

run_before = [
    ('oauth2_provider', '0001_initial'),
]

specified in it.

[jleclanche]

Closing this as 1.11 is the minimum version supported and it's been too long.