Rails 3 app model how ensure only one boolean field set to true at a time

Question

I have a Logo model that has fields of name:string, default:boolean. I want the true value to be unique, so that only one item in the database can be set to true at once. How do

Answer 1

This code is stolen from previous answer and slightly simplified:

def falsify_all_others
  Item.where('id != ?', self.id).update_all("default = 'false'")
end

You can use this method in before_save callback in your model.

Actually, it is better to "falsify" only records which values are 'true', like this:

Item.where('id != ? and default', self.id).update_all("default = 'false'")

UPDATE: to keep code DRY, use self.class instead of Item:

self.class.where('id != ? and default', self.id).update_all("default = 'false'")