Add validation on the `--name` argument in makemigrations

[Maxime Lorant]

After creating a new empty migration, I got an error when applying it. The error is pretty clear when you have the context but can be misleading for beginners: I created a migration containing a dot in its name so Django has split the migration and fails to import the module somehow.

$ python manage.py makemigrations myapp --empty -n "remove_foo.bar_thing"
Migrations for 'myapp':
  myproject/myapp/migrations/0085_remove_foo.bar_thing.py
                                            ^ notice the dot here


$ python manage.py migrate
Traceback (most recent call last):
  File "manage.py", line 6, in <module>
    execute_from_command_line(sys.argv)
  File "/data/.virtualenvs/MY_VENV/lib/python3.5/site-packages/django/core/management/__init__.py", line 371, in execute_from_command_line
    utility.execute()
  File "/data/.virtualenvs/MY_VENV/lib/python3.5/site-packages/django/core/management/__init__.py", line 365, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/data/.virtualenvs/MY_VENV/lib/python3.5/site-packages/django/core/management/base.py", line 288, in run_from_argv
    self.execute(*args, **cmd_options)
  File "/data/.virtualenvs/MY_VENV/lib/python3.5/site-packages/django/core/management/base.py", line 335, in execute
    output = self.handle(*args, **options)
  File "/data/.virtualenvs/MY_VENV/lib/python3.5/site-packages/django/core/management/commands/migrate.py", line 79, in handle
    executor = MigrationExecutor(connection, self.migration_progress_callback)
  File "/data/.virtualenvs/MY_VENV/lib/python3.5/site-packages/django/db/migrations/executor.py", line 18, in __init__
    self.loader = MigrationLoader(self.connection)
  File "/data/.virtualenvs/MY_VENV/lib/python3.5/site-packages/django/db/migrations/loader.py", line 49, in __init__
    self.build_graph()
  File "/data/.virtualenvs/MY_VENV/lib/python3.5/site-packages/django/db/migrations/loader.py", line 201, in build_graph
    self.load_disk()
  File "/data/.virtualenvs/MY_VENV/lib/python3.5/site-packages/django/db/migrations/loader.py", line 110, in load_disk
    migration_module = import_module("%s.%s" % (module_name, migration_name))
  File "/data/.virtualenvs/MY_VENV/lib/python3.5/importlib/__init__.py", line 126, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 986, in _gcd_import
  File "<frozen importlib._bootstrap>", line 969, in _find_and_load
  File "<frozen importlib._bootstrap>", line 944, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 222, in _call_with_frames_removed
  File "<frozen importlib._bootstrap>", line 986, in _gcd_import
  File "<frozen importlib._bootstrap>", line 969, in _find_and_load
  File "<frozen importlib._bootstrap>", line 956, in _find_and_load_unlocked
ImportError: No module named 'myproject.myapp.migrations.0085_remove_foo'

I suggest to add a validation step that fails when the migration name supplied with the -n/--name argument contains dots (and why not spaces too?).

To be honest, I only tried this on Django 2.0.x, but I did not see any changes about this problem in Django 2.1 releases notes.

[Herbert Fortes]

Replying to Prabakaran Kumaresshan:

Hi,

How are things going?

My first thought is to edit ​makemigrations and ​test_commands

I am not pushing. Not at all. I am just talking about the ticket. Feel free.

[Prabakaran Kumaresshan]

Replying to Herbert Fortes:

Replying to Prabakaran Kumaresshan:

Hi,

How are things going?

My first thought is to edit ​makemigrations and ​test_commands

I am not pushing. Not at all. I am just talking about the ticket. Feel free.

Hi,

This is my first contribution. I figured the code that needs patch just wondering where to place test scripts, thanks for the link.
I'll do regression and apply patch then let you know.

Much appreciate your help

[Prabakaran Kumaresshan]

​PR

[Tim Graham <timograham@…>]

In 10d82c8:

Fixed #29831 -- Added validation for makemigrations --name.