Refactor to take advantage of get_app_paths()

[Aymeric Augustin]

b55624a0263e31be80fbe7bb51e47ccd253e7a5d added a get_app_paths() method in the app cache to simplify fixture loading.

This method could be reused to simplify other code that discovers files at conventional locations inside apps (templates, translations, etc.)

[Jaap Roes]

I've identified two locations that were fairly easy to convert:

• ​django/template/loaders/app_directories.py
• ​django/utils/translation/trans_real.py (Had to modify AppResolutionOrderI18NTests so it used @override_settings)

[Jaap Roes]

I've also looked at the get_javascript_catalog view as it also traverses app directories, but I'm confused by its behavior. It takes a packages param and then re-declares it in a strange conditional list comprehension. It also doesn't reverse the packages list, is it's behavior different from trans_real? I'm not sure if get_app_paths can work there...

​django/views/i18n.py

I also thought that contrib.staticfiles would be a good candidate (the ​docstring for get_app_paths mentions it), but it doesn't seem feasible without changing the current AppDirectoriesFinder/AppStaticStorage API.

​django/contrib/staticfiles/finders.py
​django/contrib/staticfiles/storage.py

Is changing the first two code paths an acceptable fix for this ticket? Do you know of more places where get_app_paths should be used?

One last note: get_app_paths actually returns paths to models.pyc, that was not what I expected. In loaddata's fixture_dirs there's some calls to os.path.abspath, os.path.realpath and os.path.dirname, maybe this should all be done in get_app_paths itself?

[Jaap Roes]

Mmmm, running the tests again and AppResolutionOrderI18NTests still fails, thought I fixed it but apparently not. Not sure what causes the failure though...

[Aymeric Augustin]

I didn't work on this ticket because I noticed that most places that could take advantage of get_app_paths actually depend on the list of applications in INSTALLED_APPS, and not on the list of applications in the app cache.

And it's currently possible for the app cache to contain applications that aren't in INSTALLED_APPS. Switching to get_app_paths could change the results of the lookups by adding more applications to the search list.

Until app loading is in a better shape, I'm not sure we can move on with this.

[Jaap Roes]

Cool, was thinking this would be an easy one ;) Not going to put more time into this then.

[Aymeric Augustin]

get_app_paths() was deprecated during the app-loading refactor. This isn't relevant any more.