Validate presence of polymorphic parent

Question

I am developing a Rails 3.2 application with the following models:

class User < ActiveRecord::Base
  # Associations
  belongs_to :authenticatable, polymorphic         


        

Answer 1

I'm not sure if this solves your problem, but I use something like this when validating that a polymorphic parent exists.

Here is some code that I used in a video model with the parent as the polymorphic association. This went in video.rb.

  validates_presence_of :parent_id, :unless => Proc.new { |p|
      # if it's a new record and parent is nil and addressable_type is set
      # then try to find the parent object in the ObjectSpace
      # if the parent object exists, then we're valid;
      # if not, let validates_presence_of do it's thing
      # Based on http://www.rebeccamiller-webster.com/2011/09/validate-polymorphic/
      if (new_record? && !parent && parent_type)
        parent = nil
        ObjectSpace.each_object(parent_type.constantize) do |o|
          parent = o if o.videos.include?(p) unless parent
        end
      end
      parent
    }