Use the primary key in FileField and ImageField filenames
Sometimes it is desirable to use values like the primary key when naming `FileField` and `ImageField` files, but such values are only available after saving the model instance. This abstract class implements a two-phase save in order to make this case easy. See the example in the docstring. Another solution would be to write a `save()` that requires `upload_to` to be a callable that checks for `instance.pk`, then calls it again after saving. However, this would require more work from the developer for simple cases.
- imagefield
- filefield
- rename
- upload_to