sqlmigrate does not follows replaces in squashed migrations

[NeodymiumFerBore]

Hello!

I actually don't know if this issue will end being a bug, a new feature or a documentation improvement.

The sqlmigrate command does not follow replaces in squashed migration, with original (squashed) migration files deleted. This ticket is roughly the same than #33583. In #31318, the issue is marked as solved with commit ​d883657. Since then, MigrationLoader accepts the argument replace_migrations. However, ​the loader instance here has this option to False. I don't see a command option to set it to True.

Sample error (not mine, but actually the exact same, taken from #33583):

python3 manage.py sqlmigrate beta 0003
Traceback (most recent call last):
  File "/Users/amin/sandbox/mysite/manage.py", line 22, in <module>
    main()
  File "/Users/amin/sandbox/mysite/manage.py", line 18, in main
    execute_from_command_line(sys.argv)
  File "/usr/local/lib/python3.9/site-packages/django/core/management/__init__.py", line 446, in execute_from_command_line
    utility.execute()
  File "/usr/local/lib/python3.9/site-packages/django/core/management/__init__.py", line 440, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/usr/local/lib/python3.9/site-packages/django/core/management/base.py", line 414, in run_from_argv
    self.execute(*args, **cmd_options)
  File "/usr/local/lib/python3.9/site-packages/django/core/management/commands/sqlmigrate.py", line 38, in execute
    return super().execute(*args, **options)
  File "/usr/local/lib/python3.9/site-packages/django/core/management/base.py", line 460, in execute
    output = self.handle(*args, **options)
  File "/usr/local/lib/python3.9/site-packages/django/core/management/commands/sqlmigrate.py", line 46, in handle
    loader = MigrationLoader(connection, replace_migrations=False)
  File "/usr/local/lib/python3.9/site-packages/django/db/migrations/loader.py", line 58, in __init__
    self.build_graph()
  File "/usr/local/lib/python3.9/site-packages/django/db/migrations/loader.py", line 276, in build_graph
    self.graph.validate_consistency()
  File "/usr/local/lib/python3.9/site-packages/django/db/migrations/graph.py", line 198, in validate_consistency
    [n.raise_error() for n in self.node_map.values() if isinstance(n, DummyNode)]
  File "/usr/local/lib/python3.9/site-packages/django/db/migrations/graph.py", line 198, in <listcomp>
    [n.raise_error() for n in self.node_map.values() if isinstance(n, DummyNode)]
  File "/usr/local/lib/python3.9/site-packages/django/db/migrations/graph.py", line 60, in raise_error
    raise NodeNotFoundError(self.error_message, self.key, origin=self.origin)
django.db.migrations.exceptions.NodeNotFoundError: Migration beta.0001_initial dependencies reference nonexistent parent node ('first', '0001_initial')

I tried to set it to True manually in 4.1.7, and it successfully showed SQL queries involved in the migration I wanted to inspect. sqlmigrate.py has not changed between 4.1.7 and 4.2, so I guess it also affects it.

​Link: MigrationLoader instance in 4.1.7 L46
​Link: MigrationLoader instance in 4.2 L46
​Link: MigrationLoader instance in main L46

I see that it always has been like this since commit d883657. Now maybe I don't understand why it works like so. Could you explain why it is set to False with no option to set it to True in sqlmigrate? Is it unreliable? In #33583, someone said:

replaces is documented and supported only for ​squashing migrations so described flow was never officially supported

Why not adding a command option to sqlmigrate to enable following replaces in squashed migration, with a warning like "experimental" or something?

Thank you.

[David Sanders]

Hello,

Sorry I don't think there is any issue here.

The ​documentation states when removing replaced migrations, the replaces attributes must also be removed.

I ran a test to see if there were any issues with sqlmigrate & deleted squashed migrations and it behaves as expected.

Closing as invalid. If there's any extra information that comes to light or if there's something that I'm missing here feel free to add a comment 👍