Enforcing a Uniqueness Constraint in a Nested Form
- by Euwyn
I'm trying not to fight the defaults here and use Rails built-in support for nested attributes (from http://ryandaigle.com/articles/2009/2/1/what-s-new-in-edge-rails-nested-attributes). I'm labeling Things with Tags, and all works swell, and for each Thing I have a form with a nested field that creates a new Tag by a name. Trouble is, I need to make sure that each Tag has a unique name. Instead of creating a new Tag, if a user enters the name of one that already exists, I need to create the associate with that pre-existing Tag. How do I do this?