get_template_names() does not consider the queryset-only case

[Melvyn Sopacua]

In SingleObjectTemplateResponseMixin candidate names are generated using the model name. This model name is derived either from self.object or self.model but does not consider self.queryset. In the case of "create forms", self.object is unset and if self.model is not provided either, an exception is thrown much later by the template loader in select_template. This exception does not point to this method as it successfully returns an (empty) list.
The test suite kind of contains a test for this (generic_views/edit.py:test_create_without_redirect), but the problem is that the test posts data to the form and does not actually request the form. In the practical case this form could never have been submitted as it wouldn't be rendered.
Patch attached fixes the issue and creates a test.

[Melvyn Sopacua]

Fix and testcase

[Simon Charette]

IMHO replacing the hasattr(self, 'queryset') and self.queryset is not None part by getattr(self, 'queryset', None) is not None would increase readability.

[Melvyn Sopacua]

Replying to charettes:

IMHO replacing the hasattr(self, 'queryset') and self.queryset is not None part by getattr(self, 'queryset', None) is not None would increase readability.

Agreed, but it's inline with the coding style of the file, see line 150 right above. Style fixes are the committers' realm. ;)

[Jason Mayfield]

Patch applies cleanly. Test fails before applying fix. Test passes after applying fix.

[bhuztez]

#16502 is a similar problem. I guess patch there may also fix this problem.

[Tim Graham]

Patch no longer applies cleanly.

[jambonrose]

This is a duplicate of #16502. Please see that issue for resolution of this problem.