* Moved dimension field update logic out of `ImageFileDescriptor.__set__` and into its own method on `ImageField`.
* New `ImageField.update_dimension_fields` method is attached to model instance's `post_init` signal so that:
* Dimension fields are set when defined before the ImageField.
* Dimension fields are set when the field is assigned in the model constructor (fixes#11196), but only if the dimension fields don't already have values, so we avoid updating the dimensions every time an object is loaded from the database (fixes#11084).
* Clear dimension fields when the ImageField is set to None, which also causes dimension fields to be cleared when `ImageFieldFile.delete()` is used.
* Added many more tests for ImageField that test edge cases we weren't testing before, and moved the ImageField tests out of `file_storage` and into their own module within `model_fields`.
git-svn-id: http://code.djangoproject.com/svn/django/trunk@10858 bcc190cf-cafb-0310-a4f2-bffc1f526a37
At the same time, checked all other cases of db_prep_value() to ensure they
aren't making the same mistake.
git-svn-id: http://code.djangoproject.com/svn/django/trunk@8143 bcc190cf-cafb-0310-a4f2-bffc1f526a37
(via a callable). Also updates the documentation of the "default" attribute to
indicate a callable can be used. Thanks, Philipe Raoult.
git-svn-id: http://code.djangoproject.com/svn/django/trunk@7331 bcc190cf-cafb-0310-a4f2-bffc1f526a37
Changed raise to conform to PEP 3109 and wrapped the long line.
Added beginnings of tests for model fields.
git-svn-id: http://code.djangoproject.com/svn/django/trunk@5778 bcc190cf-cafb-0310-a4f2-bffc1f526a37
