Is it possible to set default value in a migration based upon another field's value?

rubyonrails-talk
1

I'm familiar with setting a field's default in the create_table within a migration via :default => some value. However, what I'm looking for is to be able to set the default value based upon the value from a different field/column. I'm not sure if this is possible or not, so any help would be greatly appreciated. The exact scenario is that I'm using devise for my authentication and I've extended it to have a login_id field in addition to the email field. I'd like to default it to the value of the email field when the user first creates their account and they can later choose to change its value if they decide they would rather use some value other than their email address. I know I can override the controller that devise uses to set this value, but I'm trying to see if I have any options that will not require me to create an overridden controller.

Thanks in advance for any guidance and help.

Chris

2

Perhaps you can use a before_create callback on the user (account?) model.

class User    before_create :default_login_id

   private    def default_login_id      self.login_id ||= self.email    end end

-Rob

Rob Biedenharn Rob@AgileConsultingLLC.com http://AgileConsultingLLC.com/ rab@GaslightSoftware.com http://GaslightSoftware.com/

3

You can put active record code into a migration:

default = Model.find(:first).name rescue nil

:default => default