id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
23556	Allow migrations to depend on a migration only part of a squashed migration	Markus Holtermann	Markus Holtermann	"If a migration depends on another migration that is part of a squashed migration (e.g. `6_auto` depends on `5_auto` which is part of `3_squashed_5`) removing the squashed migration (e.g. `5_auto`) leads to a `KeyError`:

{{{#!python
Traceback (most recent call last):
  File ""/home/markus/Coding/django/django/test/utils.py"", line 216, in inner
    return test_func(*args, **kwargs)
  File ""/home/markus/Coding/django/tests/migrations/test_loader.py"", line 263, in test_loading_squashed_complex2
    loader.build_graph()
  File ""/home/markus/Coding/django/django/db/migrations/loader.py"", line 233, in build_graph
    self.graph.add_dependency(migration, key, parent)
  File ""/home/markus/Coding/django/django/db/migrations/graph.py"", line 42, in add_dependency
    raise KeyError(""Migration %s dependencies reference nonexistent parent node %r"" % (migration, parent))
KeyError: ""Migration migrations.6_auto dependencies reference nonexistent parent node ('migrations', '5_auto')""
}}}

Thus the whole idea of `squashmigrations` to be able to eventually remove old migrations is not really working out since a 3rd party app might depend on a specific migration.

I build a testcase: https://github.com/Markush2010/django/commit/9a983d4fe66c583858eb370497d0b66227690f79"	Bug	new	Migrations	dev	Normal			Markus Holtermann	Accepted	0	0	0	0	0	0