friendly_id gem using associated model fields

Question

What should we do if we have to generate slug for a model when its associated records are updated. For example I am using models User and UserProfile and the slug is user.user_profile.name. When a new user is created the associated user_profile is also saved. The slug is generated for a new user record. But when updating the user_profile and the name is changed, the slug is not updated. Please help.

Answer 1

In a recent version of friendly_id, you can define a method to specify when to regenerate the slug (although this is probably not what you need):

  def should_generate_new_friendly_id?
    name_changed? || super
  end

You could use an after save callback on the UserProfile class to set the slug to nil and force friendly_id to regenerate the slug:

if name_changed?
  user.slug = nil
  user.save
end

That should take care of it according to the docs: http://norman.github.io/friendly_id/

Answer 2

You can override the should_generate_new_friendly_id? method. This way you can control when a new slug is being generated.

You could do something like this

class User < ActiveRecord::Base
  extend FriendlyId
  friendly_id :my_friendly_id_method, :use => :slugged

  def should_generate_new_friendly_id?
    user_profile.changed?
  end
end