Ruby-on-rails – Rails: Overriding ActiveRecord association method

activerecordoverridingrubyruby-on-rails

Is there a way to override one of the methods provided by an ActiveRecord association?

Say for example I have the following typical polymorphic has_many :through association:

class Story < ActiveRecord::Base
    has_many :taggings, :as => :taggable
    has_many :tags, :through => :taggings, :order => :name
end


class Tag < ActiveRecord::Base
    has_many :taggings, :dependent => :destroy
    has_many :stories, :through => :taggings, :source => :taggable, :source_type => "Story"
end

As you probably know this adds a whole slew of associated methods to the Story model like tags, tags<<, tags=, tags.empty?, etc.

How do I go about overriding one of these methods? Specifically the tags<< method. It's pretty easy to override a normal class methods but I can't seem to find any information on how to override association methods. Doing something like

def tags<< *new_tags
    #do stuff
end

produces a syntax error when it's called so it's obviously not that simple.

Best Answer

You can use block with has_many to extend your association with methods. See comment "Use a block to extend your associations" here.
Overriding existing methods also works, don't know whether it is a good idea however.

  has_many :tags, :through => :taggings, :order => :name do
    def << (value)
      "overriden" #your code here
      super value
    end     
  end
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