biola/buweb-content-models — pull request #168 by halloffame (2014-11-25 20:02:28+00:00)
Title: Fixing nil to string error in Attachment#to_s

This was erroring when attachment was nil
(for example, if you just initialized a new Attachment without setting any value, and haven't saved it yet.)
I was getting the following error

TypeError:
no implicit conversion of nil into String

This should fix the tests in this PR https://github.com/biola/academic-publisher/pull/17