Validating Uniqueness From Two Database Tables?

rubyonrails-talk
1

Well, I'm working on adding a new type of user (organization) to my application, using a different database table than the standard User table (in the end, I think it works out being easier to deal with than creating another column in the original User table for account type). However, I'm running into a user registration problem. I can register both types of users fine, however, a screen name can be shared between the different tables. For example, a user can register with the screen name "foo", and an organization can also register with the screen name "foo". Obviously, this creates login problems, so I'd like to try to prevent this. Unless theres something I'm missing about "validates_uniqueness_of", that only works within one table. How can I make my program check that the new screen name is unique to both tables?

Thanks for any help :slight_smile:

2

Hi Dan,

One way that springs to mind is:

class Organisation   validate :validates_uniqueness_of_screen_name      def validates_uniqueness_of_screen_name     in_org = Organisation.find(:first, :conditions => ['screen_name
= ?', screen_name])     in_user = in_org ? nil : User.find(:first, :conditions =>
['screen_name = ?', screen_name])     errors.add('screen_name', 'is already taken') if in_org or in_user   end end

class User   validate :validates_uniqueness_of_screen_name      def validates_uniqueness_of_screen_name     in_org = Organisation.find(:first, :conditions => ['screen_name
= ?', screen_name])     in_user = in_org ? nil : User.find(:first, :conditions =>
['screen_name = ?', screen_name])     errors.add('screen_name', 'is already taken') if in_org or in_user   end end

You could even add this in as a mixin if you feel inspired (that way
you don't repeat yourself) :slight_smile:

Julian.

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3

That works absolutely perfectly, thanks a bunch for your help Julian :slight_smile:

4

I have a feeling that this could get very, very messy. IMO you're better off using single table inheritance in the User table.