[Django] #30035: many to many through table not recognisable in custom migration

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Django

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Dec 12, 2018, 7:28:07 AM12/12/18
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#30035: many to many through table not recognisable in custom migration
-------------------------------------+-------------------------------------
Reporter: | Owner: nobody
jainmickey |
Type: Bug | Status: new
Component: | Version: 2.0
Migrations | Keywords: many to many,
Severity: Normal | through
Triage Stage: | Has patch: 0
Unreviewed |
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
-------------------------------------+-------------------------------------
I have a model `A` having field `b` as many to many. I wanted to make `b`
default through table's default id field to be UUID.
If I do that using through table, the admin interface changes to Inline
and I don't want that. So, I tried writing a custom migration to do that.

If I am checking the default intermediate table using `apps.get_model` it
exists but when I use the same table in migrations it gives me error:

```
File "./manage.py", line 19, in <module>
execute_from_command_line(sys.argv)
File "/Users/mj/.virtualenvs/proj/lib/python3.6/site-
packages/django/core/management/__init__.py", line 371, in
execute_from_command_line
utility.execute()
File "/Users/mj/.virtualenvs/
proj/lib/python3.6/site-packages/django/core/management/__init__.py", line
365, in execute
self.fetch_command(subcommand).run_from_argv(self.argv)
File "/Users/mj/.virtualenvs/proj/lib/python3.6/site-
packages/django/core/management/base.py", line 288, in run_from_argv
self.execute(*args, **cmd_options)
File "/Users/mj/.virtualenvs/proj/lib/python3.6/site-
packages/django/core/management/base.py", line 335, in execute
output = self.handle(*args, **options)
File "/Users/mj/.virtualenvs/proj/lib/python3.6/site-
packages/django/core/management/commands/migrate.py", line 200, in handle
fake_initial=fake_initial,
File "/Users/mj/.virtualenvs/proj/lib/python3.6/site-
packages/django/db/migrations/executor.py", line 117, in migrate
state = self._migrate_all_forwards(state, plan, full_plan, fake=fake,
fake_initial=fake_initial)
File "/Users/mj/.virtualenvs/proj/lib/python3.6/site-
packages/django/db/migrations/executor.py", line 147, in
_migrate_all_forwards
state = self.apply_migration(state, migration, fake=fake,
fake_initial=fake_initial)
File "/Users/mj/.virtualenvs/proj/lib/python3.6/site-
packages/django/db/migrations/executor.py", line 244, in apply_migration
state = migration.apply(state, schema_editor)
File "/Users/mj/.virtualenvs/proj/lib/python3.6/site-
packages/django/db/migrations/migration.py", line 112, in apply
operation.state_forwards(self.app_label, project_state)
File "/Users/mj/.virtualenvs/proj/lib/python3.6/site-
packages/django/db/migrations/operations/fields.py", line 70, in
state_forwards
state.models[app_label,
self.model_name_lower].fields.append((self.name, field))
KeyError: ('app', 'A_b')
```

--
Ticket URL: <https://code.djangoproject.com/ticket/30035>
Django <https://code.djangoproject.com/>
The Web framework for perfectionists with deadlines.

Django

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Dec 12, 2018, 7:30:11 AM12/12/18
to django-...@googlegroups.com
#30035: many to many through table not recognisable in custom migration
-------------------------------------+-------------------------------------
Reporter: jainmickey | Owner: nobody
Type: Bug | Status: new
Component: Migrations | Version: 2.0
Severity: Normal | Resolution:
Keywords: many to many, | Triage Stage:
through | Unreviewed
Has patch: 0 | Needs documentation: 0

Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Description changed by jainmickey:

Old description:

New description:

{{{

--

--
Ticket URL: <https://code.djangoproject.com/ticket/30035#comment:1>

Django

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Dec 12, 2018, 10:33:38 AM12/12/18
to django-...@googlegroups.com
#30035: many to many through table not recognisable in custom migration
-------------------------------------+-------------------------------------
Reporter: jainmickey | Owner: nobody
Type: Bug | Status: closed
Component: Migrations | Version: 2.0
Severity: Normal | Resolution: needsinfo

Keywords: many to many, | Triage Stage:
through | Unreviewed
Has patch: 0 | Needs documentation: 0

Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Changes (by Simon Charette):

* status: new => closed
* resolution: => needsinfo


Comment:

It's unfortunately impossible to determine if Django is at fault with the
little details you provided so far.

The fact that you mention writing a custom migration without providing it
makes it likely that the issue lies there.

Please note that simply adding a `through` to a `ManyToManyField` or
manually adding an `AlterField` to add the through is not working yet
#23034.

If you have any details that proves that Django is at fault and that this
report is not a duplicate of #23034 please provide them and reopen this
issue.

--
Ticket URL: <https://code.djangoproject.com/ticket/30035#comment:2>

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