问题
Back in previous versions of Django, we all used South to do migrations, and because it wasn't as smart as we might have liked, we sometimes needed to tell it to explicitly ignore some fields because such fields were too complicated for it to handle. We did this with add_ignored_fields and everything pretty much worked.
In our case, we have a "field" on our model that's a subclass of CharField that actually attaches two additional fields to the model via the contribute_to_class method. It's kind of a weird process, but it makes sense for our use case and worked just fine until we upgraded to Django 1.7.
However, with the new migrations system, our use of add_ignored_fields() no longer works and our unit tests are exploding as it tries to create a test database table with these fields. Specifically it says:
django.db.utils.OperationalError: duplicate column name: our_column_name
In this case our_column_name is one of the fields this special CharField subclass creates.
In a perfect world, we could have the migration code handle these fields properly, but I'd settle for the 1.7 version of add_ignored_fields() if it exists.
I should also point out that we've found the explanation for deconstruct in the Django documentation, but I'm afraid that it doesn't make any sense to me. I can't figure out if it applies to this situation or not.
回答1:
We've discovered this Django ticket that pretty much states that this is a design pattern that the devs aren't supporting, so we're just going to have to rewrite the model to explicitly create the other fields on the model and then reference said fields from the "parent" field a la ImageField.
来源：https://stackoverflow.com/questions/27606178/whats-the-django-1-7-equivalent-to-souths-add-ignored-fields