Legacy Table Creation Methods Not Properly Deprecated

[Mark Lavin]

As noted in ​https://github.com/django/django/commit/1cb6729f58ef14c2042373d8bd61fa264a955705 and ​https://groups.google.com/d/msg/django-developers/PWPj3etj3-U/vH4DjnVttIUJ the DB backend DatabaseCreation class and the legacy path for table creating in the migrate command are being removed. DatabaseCreation is a documented part of the API in ​https://docs.djangoproject.com/en/1.6/topics/testing/advanced/#django-db-connection-creation and is still actively used in Django's code and test suite. For this to be deprecated per Django's published policy these should raise a deprecation warning when used prior to removal and currently neither do.

[Tim Graham]

I'm going to change the version of this to master so we don't consider it a release blocker for 1.7. from Andrew in the ​django-dev thread:

"Yes, the test suite is basically the biggest obstacle to full usage of migrations - I've tried to make it see sense, but given my limited time at the moment and the fact that it's a tortuous mess of hacks in places it means that I can't see that happening before the RC.

I'd like to have started the Creation deprecation cycle this release, but it's probably fine if we let that slip a release (it's going to be harder to remove than many other features). Migrations will hopefully drive the adoption of SchemaEditor by developers and third-party backends anyway."

We'll need to update the deprecation timeline and 1.7 release at some point once this punt is confirmed for sure.

[Andrew Godwin <andrew@…>]

In 61da5f3f02f34810aaa6fcddac3808318a5b95c4:

Bump DatabaseCreation deprecation to 2.0 (refs #22340)

[Tim Graham <timograham@…>]

In 10327be1f3f9fed5dc40f6fe42e5494afcf7aa76:

[1.7.x] Bump DatabaseCreation deprecation to 2.0 (refs #22340)

Backport of 61da5f3f02 from master

[Tim Graham <timograham@…>]

In a2e3c9694823d6d451d6dd234e9d416600aacc68:

Updated some docs for the delayed deprecation of legacy table creation; refs #22340.

[Tim Graham <timograham@…>]

In af06203cead2968f4d58a718100dedc0faa7c619:

[1.7.x] Updated some docs for the delayed deprecation of legacy table creation; refs #22340.

Backport of a2e3c96948 from master

[Markus Amalthea Magnuson]

I gather this ticket should be unmarked as release blocker for now, no?

[Tim Graham]

The Trac UI isn't very intuitive, but it's a release blocker for 1.8 (currently master) as indicated by the "Version" flag.

[Claude Paroz]

This pull request is aiming to move more DDL instructions go through schema editors, mainly migrate in sync_apps.
We'll also see what's the CI server thinks about that...
​https://github.com/django/django/pull/3220

[Claude Paroz <claude@…>]

In 30cbd5d360a2b8becdef7c6a0c939e0633a5468e:

Replaced DatabaseCreation sql methods by schema editor equivalents

Also used schema editor in migrate to sync unmigrated apps (sync_apps).
Refs #22340. Thanks Tim Graham for the review.

[Tim Graham]

The remaining work for this ticket seems to be to replace the documented django.db.connection.creation methods (create_test_db() and destroy_test_db()) with a SchemaEditor equivalent. I think all of the DatabaseCreation methods that deal with generating SQL don't need to go through a deprecation cycle as they will be unused in Django 1.9 when support for apps without migrations is removed.

[Tim Graham <timograham@…>]

In d7fc6eb8ca67a6a628e8c7ce669731cf563606e7:

Revert "Updated some docs for the delayed deprecation of legacy table creation; refs #22340."

This reverts commit a2e3c9694823d6d451d6dd234e9d416600aacc68.

The deprecation was moved back to 1.9 in
61da5f3f02f34810aaa6fcddac3808318a5b95c4.

[Tim Graham <timograham@…>]

In 9311a94ca50ac86f9c945922c212c6e605d2d90a:

[1.7.x] Revert "Updated some docs for the delayed deprecation of legacy table creation; refs #22340."

The deprecation was moved back to 1.9 in
61da5f3f02f34810aaa6fcddac3808318a5b95c4.

Backport of d7fc6eb8ca67a6a628e8c7ce669731cf563606e7 from master

[Tim Graham]

After looking at this some more, I am not sure there is an actual benefit or need to move the code that deals with test database creation and to remove the DatabaseCreation class. It seems to me to be a clear separation of concerns to keep this code where it is (after all, it deals with database creation).

If that rationale is accepted, the remaining cleanups are:

1. Move the DatabaseCreation.data_types properties to DatabaseWrapper as proposed in ​pull request 3810.
2. Remove the legacy SQL generation methods when support for apps without migrations is dropped in Django 1.9 (done in the commit "Removed obsolete SQL generation methods." commit of ​pull request 3791).
3. Remove the note about DatabaseCreation from the deprecation timeline.

This will leave create_test_db(), destroy_test_db(), and their helper methods as the only functionality remaining on the DatabaseCreation class.

[Tim Graham <timograham@…>]

In 93d73dac91104fd82d44b0dd4521cfa4f31e02aa:

Moved DatabaseCreation.data_types properties to DatabaseWrapper.

refs #22340.

[Tim Graham <timograham@…>]

In 478d6a950361ef541ff40b51b7c04439647e0492:

Copied BaseDatabaseCreation._digest() to SchemaEditor to remove dependency.

refs #22340.

[Claude Paroz]

OK with the plan. I'm just not sure if we really have to drop support for apps without migrations, but that's not the subject of this ticket.

[Tim Graham <timograham@…>]

In 09bce0b2cb6813e1b7acf184a1e26402736618a0:

Fixed #22340 -- Removed DatabaseCreation deprecation from timeline.