undefined local variable or method `autosave_associated_records_for_book' when saving record

So, I'm at a loss trying to figure out where I screwed something up here.

I've got (what I think should be) a fairly straight-forward record setup, but when I try to create/save a BookEdition record, I get the following error: NameError: undefined local variable or method `autosave_associated_records_for_book_editions_users'

I'm actually getting two slightly different errors, but with almost the exact same output:

So, to answer my own question, and in the hope of saving others the same frustration I went through:

The problem was that as part of the book_editions table, I had a field named 'binding'. This caused ActiveRecord to blow up in very cryptic ways. Renaming 'binding' to 'binding_type' got rid of the errors.