On Mon, Dec 1, 2008 at 11:07 AM, Gearóid O'Ceallaigh
<[EMAIL PROTECTED]> wrote:
>
> Hey,
>
> I'm creating an app which has two models - bands and users. A
> relationship between users and bands in many to many.
>
> However, when I'm adding an existing to user to a band (ie. updating
> the bands_users table) how can i check if the relationship between the
> user and the band already exists? For example, if a user with ID of 3
> was already a member of a band with ID 5, and then somebody tried to
> make this connection again - I want to output an error message. Is
> there some special validation I can place in a bands_users.rb that
> validated the uniqueness of the entire record?
There is a :uniq option that will ignore duplicates:
class Band < ActiveRecord::Base
has_and_belongs_to_many :users, :uniq => true
end
This won't raise an error, but it will prevent duplicate associations.
Hope that Helps
Brandon
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