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As someone fairly new to Django, this is confusing me a little bit.

I have a working Django 1.6 app where using a proxy model as a foreign key didn't seem to throw any errors, and the app works.

Testing out Django 1.7a2 however, does not seem to allow this. The Django 1.7 migrations throw an error indicating that the proxy model "cannot be resolved."

For more info on the error I'm getting in 1.7a2, see this post: Possible bug in Django 1.7a2 Migrations?

After some digging around on the net, it seems that allowing proxy models as foreign keys in 1.6 may have been a bug in that some databases will complain, and some will allow it, but you aren't really supposed to be doing it.

Here's one example from South: http://south.aeracode.org/ticket/436 But this SO post seem to indicate it's completely acceptable? Assigning a proxy model instance to foreign key

I can't seem to find any indication in the docs either.

For example:

class Receipt(models.Model):
    date = models.DateField()
    amount = models.DecimalField(max_digits=7, decimal_places=2)


class ReturnReceipt(Receipt)
    class Meta:
        proxy = True

    def return_status(self):
        pass


class ReturnsLedger(modesl.Model):
    return_receipt = models.ForeignKey(ReturnReceipt)

Update: Git repo for the example above for someone to try on 1.7 and confirm https://github.com/cgon/djtester

Thanks!

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Brownbay
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  • This doesn't have anything to do with the database (and neither of those links mention databases). The db is only aware of the table, and the table of ReturnReceipt is the same as the one for Receipt. – Daniel Roseman Mar 17 '14 at 13:38
  • Have you tried to do something similar in 1.7? I just put the code above into a sample project and am greeted with the following error: "ValueError: Related model 'testapp.ReturnReceipt' cannot be resolved" - after trying to run manage.py migrate – Brownbay Mar 17 '14 at 13:59
  • It seems like Sqlite3 does not throw the error, but using Postgres as the backend does. A temporary fix right now would be to NOT use proxy models as foreign keys. Since Django does not natively support polymorphic models, this bug isn't the end of the world. – Brownbay Mar 17 '14 at 16:25

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