contentypes generic module has core functionality plus admins-specific one

[Ramiro Morales]

(Copied and adapted from https://code.djangoproject.com/ticket/16368#comment:16)

Consider a project with a foo and a bar apps listed on INSTALLED_APPS:

• foo uses generic foreign keys, with the following models.py:

  from django.db import models
  from django.contrib.contenttypes.models import ContentType
  from django.contrib.contenttypes import generic
  
  class TaggedItem(models.Model):
      tag = models.SlugField()
      content_type = models.ForeignKey(ContentType)
      object_id = models.PositiveIntegerField()
      content_object = generic.GenericForeignKey()
  

• bar has a Site model:

  from django.db import models
  
  class Site(models.Model):
      name = models.CharField(...
      # ...
  

• Neither the admin nor sites Django apps are being used.

This causes the user's Site model to be overridden and masked by Django sites framework's one.

This is because the django/contrib/contenttypes/generic.py module contain both the definitions of the model-related generic stuff (GenericForeignKey, etc.) AND the admin app-related specialized inlines (GenericInlineModelAdmin, GenericStackedInline, GenericTabularInline.)

Maybe it's time we move the latter ones from django.contrib.contenttypes.generic to, say, a new generic_admin (or admin_tools?) on django.contrib.contenttypes?. Of course this would need a deprecation process.

[Simon Charette]

As discussed on IRC with ramiro and loic splitting the generic module into fields and admin and deprecating the former should fix the issue.

I couldn't reproduce the Site cloaking with you described example against 1.6 and master. The only way I managed to reproduce is by having a sites app, just like it's described in #16368.

[Simon Charette]

@ramiro, I created a ​PR missing release notes and documentation adjustment. I'll try to work on it in the new few days but if you want to pick it up from here feel free to do it.

[Simon Charette]

I adjusted the documentation and added a release note. The PR should be ready for review.

[loic84]

Looks good to me, I'm pretty happy with the forms.py, fields.py, admin.py split up.

[Carl Meyer]

Looks good to me; good idea to remove everything from that module and just deprecate the module, that's a lot simpler than the previous approach.

I won't claim to have reviewed all the minor changes to docs and tests in detail, but I assume if you've run the tests and they are warning-free that that was all done correctly. Looks good to me!

[Carl Meyer]

(I did make a couple comments on wording of docs and error messages.)

[Ramiro Morales]

Simon,

I had some unfinished work in that direction and was a bit uncomfortable about still having the formset definition in the new fields module. Good call on creating forms.py

Please go ahead, my review didn't find anything.

[Simon Charette <charette.s@…>]

In 10e3faf191d8f230dde8534d1c8fad8c8717816e:

Fixed #19774 -- Deprecated the contenttypes.generic module.

It contained models, forms and admin objects causing undesirable
import side effects. Refs #16368.

Thanks to Ramiro, Carl and Loïc for the review.

[Tim Graham <timograham@…>]

In 3b89d2d540a96ffd33c294b576147ff800b16632:

Removed contrib.contenttypes.generic per deprecation timeline; refs #19774.

[Tim Graham <timograham@…>]

In 737cd4ff3decfd3e709885d219e70d8395305965:

[1.8.x] Clarified contrib.contenttypes.generic deprecation; refs #19774.

[Tim Graham <timograham@…>]

In 4df91d05e8ffca15f58d09d9fd0f0ae16891565b:

[1.7.x] Clarified contrib.contenttypes.generic deprecation; refs #19774.

Backport of 737cd4ff3decfd3e709885d219e70d8395305965 from stable/1.7.x