Add warning if model field has trailing comma.

[Jonas Haag]

If someone types (note the trailing comma):

class MyModel(models.Model):
  trailing_comma = models.IntegerField(),

Django silently ignored the field, possibly leaving you wondering for a very long time what's going on.

I suggest to add a warning to the models checker framework.

If accepted, I'm willing to come up with an initial patch.

[Mariusz Felisiak]

Thanks for this ticket, however we cannot add a system check for tuples defined on models. It's a supported use case.

[Jonas Haag]

What do you mean by “supported use case”? Obviously defining tuples on model classes generally should not raise a warning, but how about the specific case of tuple of size 1 containing a model field instance?

[Jonas Haag]

From a quick Google search, this seems to be a common mistake made by a Django beginners.

​https://stackoverflow.com/questions/7900162/django-error-with-orm/7900323#7900323
​https://stackoverflow.com/questions/26090949/unique-together-refers-to-the-non-existent-field
​https://stackoverflow.com/questions/4389367/django-unique-together-does-not-allow-foreignkey-field-across-applications-when

[Mariusz Felisiak]

It is too specific, we cannot add separate system checks for each kind of typos.