Modifying a rails model at runtime

on a previous question, I was searching for a way to dynamic valitating my models.

Advice on "Dynamic" Model validation

The solution that I got working is:

def after_initialize        
  singleton = class << self; self; end

  validations = eval(calendar.cofig)

  validations.each do |val|
    singleton.class_eval(val)
  end
end

On my actual app, I have 2 models

class Calendar < ActiveRecord::Base
  has_many :events
end

class Event < ActiveRecord::Base
  belongs_to :calendar

  def after_initialize        
    singleton = class << self; self; end

    validations = eval(calendar.cofig)

    validations.each do |val|
       singleton.class_eva开发者_如何学JAVAl(val)
    end
 end

end

As you can see, the validation code that should be added to the Event class lies on the Calendar field "config".

Works fine for a existing Event, but doesn't for a new record. That's because, at the time that after_initialize is called, the association doesn't exists yet.

I can't find a way to do that besides putting the config values on Event itself.

Any advices?

Tks!

---

You probably want to run your validation code during the validation phase, not the initialize phase. Try this:

class Calendar < ActiveRecord::Base
  has_many :events
end

class Event < ActiveRecord::Base
  belongs_to :calendar

  validate do |event|
    validations = eval(calendar.cofig)
    validations.each do |val|
      eval(val)
    end
  end
end