Snippet: MyModel.options_for_select

How many times have you written a quickie drop-down box to choose one instance of an associated model? Here's a quickie monkey-patch that will help. Put the following in environment.rb (or similar):

class ActiveRecord::Base
  # convenience method for selection boxes of this model
  # Assumes existance of a function "display_name" that will be a
  # displayable name for the select box.
  def self.options_for_select
    self.find(:all).map {|p| [p.display_name, p.id] }
  end
end

Make sure you have a function in your model named "display_name" that returns what you'd like to see in your drop-down, eg:

class Person < ActiveRecord::Base
  has_many :posts

  # convenience method for the person's name
  def display_name
    [first_name, last_name].compact.join(', ')
  end
end
class Post < ActiveRecord::Base
  belongs_to :person

  alias :display_name :title
end

Then use in a view (eg as follows):

<% form_for(@person) do |f| %>
<p>Pick a post: <%= f.select :post_id, Post.options_for_select -%><%= f.submit 'Go!' -%></p>
<% end %>