Rails - Oct 2005 - Explanation of how Scope works?

Hello all,

I was wondering if someone could give me a brief explanation of  
how :scope works.  I believe I''ve seen it used with the validation  
helpers in the past.

- Jim

If you have a look at the docs for ''validates_uniqueness_of'',
you''ll
see this example:

  class Person < ActiveRecord::Base
    validates_uniqueness_of :user_name, :scope => "account_id"
  end

Basically, what that means is that the vaildation of user_name will
not just be checked against _all_ other usernames, it will instead be
checked against only those usernames where the account_id is the same
as the model under validation.

HTH,
Dan

Dan Sketcher wrote:
>If you have a look at the docs for
''validates_uniqueness_of'', you''ll
>see this example:
>
>  class Person < ActiveRecord::Base
>    validates_uniqueness_of :user_name, :scope => "account_id"
>  end
>
>Basically, what that means is that the vaildation of user_name will
>not just be checked against _all_ other usernames, it will instead be
>checked against only those usernames where the account_id is the same
>as the model under validation.
>
>HTH,
>Dan
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>
>  
>
Wow, thanks for that. I had written a custom (ugly) validation to do the 
same thing but that is much nicer.

Cheers,
Sam