Rails - Jul 2005 - RE: Validations and belongs_to: etc - MY SOLUTION

For the record, I ended up coding a validate method on the model like
so:

def validate
  errors.add("", "Group #{self[''group_id'']} Not
Found") unless
Group.exists?(self["group_id"])
end 

I like Ruby and Rails problems often distill down to neat one liners ...


-----Original Message-----
From: rails-bounces-1W37MKcQCpIf0INCOvqR/iCwEArCW2h5@public.gmane.org
[mailto:rails-bounces-1W37MKcQCpIf0INCOvqR/iCwEArCW2h5@public.gmane.org] On
Behalf Of Neville
Burnell
Sent: Monday, 18 July 2005 1:27 PM
To: rails-1W37MKcQCpIf0INCOvqR/iCwEArCW2h5@public.gmane.org
Subject: [Rails] Validations and belongs_to: etc

Hi,

Say I have two models, User and Group whereby each User belongs to a
Group, like so:

  class User < ActiveRecord::Base
    belongs_to :Group
  end

  class Group < ActiveRecord::Base
    has_many :Users
  end

Whats "The Rails Way" TM to add a ''lookup''
validation to the User model
such that Rails will check that the group exists in the DB on saving ?

eg:

  u = User.new
  u[''group_id''] = group_id
  u.save

I''ve looked at the ''validates_...'' helpers, but
couldn''t find what I was
looking for, ie, something like:

  validate_exists :group

At the moment, the way forward seems to be something like:

  u = User.new
  u[''group_id''] = group_id
  if u.group.nil?
  # group_id not valid ... do something
  end
  u.save

But I''d rather code something that fits with the Rails
''validates_''
framework

Any comments welcome

Nev



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