Override ActiveRecord attribute methods

Question

An example of what I\'m talking about:

class Person < ActiveRecord::Base
  def name=(name)
    super(name.capitalize)
  end
  def name
    super().downcas         


        

Answer 1

Echoing Gareth's comments... your code will not work as written. It should be rewritten this way:

def name=(name)
  write_attribute(:name, name.capitalize)
end

def name
  read_attribute(:name).downcase  # No test for nil?
end

Answer 2

I have a rails plugin that makes attribute overriding work with super as you would expect. You can find it on github.

To install:

./script/plugin install git://github.com/chriseppstein/has_overrides.git

To use:

class Post < ActiveRecord::Base

  has_overrides

  module Overrides
    # put your getter and setter overrides in this module.
    def title=(t)
      super(t.titleize)
    end
  end
end

Once you've done that things just work:

$ ./script/console 
Loading development environment (Rails 2.3.2)
>> post = Post.new(:title => "a simple title")
=> #<Post id: nil, title: "A Simple Title", body: nil, created_at: nil, updated_at: nil>
>> post.title = "another simple title"
=> "another simple title"
>> post.title
=> "Another Simple Title"
>> post.update_attributes(:title => "updated title")
=> true
>> post.title
=> "Updated Title"
>> post.update_attribute(:title, "singly updated title")
=> true
>> post.title
=> "Singly Updated Title"

Answer 3

As an extension to Aaron Longwell's answer, you can also use a "hash notation" to access attributes that have overridden accessors and mutators:

def name=(name)
  self[:name] = name.capitalize
end

def name
  self[:name].downcase
end

Answer 4

There is some great information available on this topic at http://errtheblog.com/posts/18-accessor-missing.

The long and short of it is that ActiveRecord does correctly handle super calls for ActiveRecord attribute accessors.