#25313: Document how to migrate from a built-in User model to a custom User 
model
-------------------------------+------------------------------------
     Reporter:  Carl Meyer     |                    Owner:  nobody
         Type:  New feature    |                   Status:  new
    Component:  Documentation  |                  Version:  1.8
     Severity:  Normal         |               Resolution:
     Keywords:                 |             Triage Stage:  Accepted
    Has patch:  0              |      Needs documentation:  0
  Needs tests:  0              |  Patch needs improvement:  0
Easy pickings:  0              |                    UI/UX:  0
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Comment (by dustingtorres):

 Replying to [comment:2 Aymeric Augustin]:
 > I did it at least twice. Unfortunately I don't remember all the details.
 >
 > I think a reasonable procedure is:
 >
 > 1. Create a custom user model identical to `auth.User`, call it `User`
 (so many-to-many tables keep the same name) and set `db_table='auth_user'`
 (so it uses the same table)
 > 2. Throw away all your migrations
 > 3. Recreate a fresh set of migrations
 > 4. Sacrifice a chicken, perhaps two if you're anxious; also make a
 backup of your database
 > 5. Truncate the `django_migrations` table
 > 6. Fake-apply the new set of migrations
 > 7. Unset `db_table`, make other changes to the custom model, generate
 migrations, apply them
 >
 > It is highly recommended to do this on a database that enforces foreign
 key constraints. Don't try this on SQLite on your laptop and expect it to
 work on Postgres on the servers!

 Thanks for this, I followed your steps and Justin Smith's notes and want
 to add one more:

 6b. Any model that has a link to ContentType may be linked to the now
 stale auth.User content type. I went through and updated all models that
 were pointing to auth.User content type to my new User model. You can find
 out what type of objects would be removed due to cascading delete of the
 stale auth.User content type by running `manage.py
 remove_stale_contenttypes` **and make sure to answer NO** when asked if
 you want to proceed.

 If you don't unset `db_table` the above step may be optional since the
 content type lookup will use auth.User model which will still have a valid
 database table (although I don't recommend relying on this).

-- 
Ticket URL: <https://code.djangoproject.com/ticket/25313#comment:12>
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