Is it really needed to validate foreign keys?

问题

I am using Ruby on Rails v3.2.2 and, after post my previous question, I would like to know and understand if (or not) to explicitly validate foreign keys related to ActiveRecord::Associations is needed. For example:

class CategoryAssociation < ActiveRecord::Base
  belongs_to :article, :foreign_key => 'article_id'
  belongs_to :category, :foreign_key => 'category_id'

  validates :article_id, :presence => true, :numericality => { :only_integer => true }
  validates :category_id, :presence => true, :numericality => { :only_integer => true }
end

Are above validates methods really needed? Why?

回答1:

I would not do it the way you're doing it, but I would do:

validates_presence_of :article, :category

I'm not sure its absolutely necessary, but this prevents you from being able to save only a partial association. It would be hard to create a partial association in normal rails usage, but this way it would not happen.

Also, you don't need foreign_key on either of those associations, just