rails/rails — pull request #4856 by ihid (2012-02-02 19:11:02+00:00)
Title: Allow store to be a not null column.

Pull request to fix issue #4840 (cc @tenderlove)

I don't really like the fact it's checking the variable every time the column is accessed, but unless we want to play around with the initialisation of the variable, it seems to be the most robust way.