Misleading migrate "App 'apps.somethings' does not have migrations." error message with nested apps

[oliver]

If you have a couple of nested apps, or apps that are not available directly in the top-level namespace and you use migrate command, and pass the full dotted path to this command, the error message is somewhat misleading:

CommandError: App 'apps.somethings' does not have migrations.

In this case, the somethings app have migrations, but migrate command expecting just app_label.

And there is the other misleading error message.
If you use migrate command and pass nonexistent app in your INSTALLED_APP, the error message is somewhat misleading:

CommandError: App 'nonexistent_app' does not have migrations.

In this case, the nonexistent_app does not exist, but the error message make user think that nonexistent app just don't have migrations.

Currently, makemigrations command check for existence and validity of app. As follows

       # Make sure the app they asked for exists
        app_labels = set(app_labels)
        bad_app_labels = set()
        for app_label in app_labels:
            try:
                apps.get_app_config(app_label)
            except LookupError:
                bad_app_labels.add(app_label)
        if bad_app_labels:
            for app_label in bad_app_labels:
                if '.' in app_label:
                    self.stderr.write(
                        "'%s' is not a valid app label. Did you mean '%s'?" % (
                            app_label,
                            app_label.split('.')[-1],
                        )
                    )
                else:
                    self.stderr.write("App '%s' could not be found. Is it in INSTALLED_APPS?" % app_label)
            sys.exit(2)

How about checking that in migrate command?

This ticket is very similar to https://code.djangoproject.com/ticket/29469.

But it is about migrate not makemigrations.
Please read this ticket.

[oliver]

​https://github.com/django/django/pull/10061

I added code as follows

+        # Make sure the app they asked for exists
+        if options['app_label']:
+            app_label = options['app_label']
+            try:
+                apps.get_app_config(app_label)
+            except LookupError:
+                if '.' in app_label:
+                    raise CommandError(
+                        "'%s' is not a valid app label. Did you mean '%s'?" % (
+                            app_label,
+                            app_label.split('.')[-1],
+                        )
+                    )
+                else:
+                    raise CommandError("App '%s' could not be found. Is it in INSTALLED_APPS?" % app_label)