rails-plugins.md

   1 ---
   2 title: Rails plugins
   3 category: Rails
   4 ---
   5
   6 Generate a plugin
   7 -----------------
   8
   9 Generate a Rails Engine plugin:
  10
  11     rails plugin new myplugin --skip-bundle --full
  12
  13 Initializers
  14 ------------
  15
  16 * [Rails::Railtie](http://edgeapi.rubyonrails.org/classes/Rails/Railtie.html)
  17 * [EngineYard blog
  18   post](http://www.engineyard.com/blog/2010/extending-rails-3-with-railties/)
  19
  20 Subclass Railtie and provide an `initializer` method.
  21
  22     module NewPlugin
  23       class Railtie < Rails::Railtie
  24         initializer "newplugin.initialize" do |app|
  25
  26           # subscribe to all rails notifications: controllers, AR, etc.
  27           ActiveSupport::Notifications.subscribe do |*args|
  28             event = ActiveSupport::Notifications::Event.new(*args)
  29             puts "Got notification: #{event.inspect}"
  30           end
  31
  32         end
  33       end
  34     end
  35
  36 Custom routes
  37 -------------
  38
  39 * [ActionDispatch::Routing::Mapper](http://api.rubyonrails.org/classes/ActionDispatch/Routing/Mapper.html)
  40
  41 To create custom `routes.rb` keywords:
  42
  43     # # routes.rb:
  44     # myplugin_for x
  45     #
  46     class ActionDispatch::Routing
  47       class Mapper
  48         def myplugin_for(*x)
  49         end
  50       end
  51     end
  52
  53 Example with a block:
  54
  55     # authenticated do
  56     #   resources :users
  57     # end
  58     #
  59     def authenticated
  60       constraint = lambda { |request| request... }
  61
  62       constraints(constraint) { yield }
  63     end
  64
  65 Custom generators
  66 -----------------
  67
  68 * [Guide: generators](http://guides.rubyonrails.org/generators.html)
  69 * [ActiveRecord::Generators::Base](http://api.rubyonrails.org/classes/ActiveRecord/Generators/Base.html)
  70
  71 ### Basic
  72
  73     # rails g initializer
  74     # lib/generators/initializer_generator.rb
  75     class InitializerGenerator < Rails::Generators::Base
  76       def create_initializer_file
  77         create_file "config/initializers/initializer.rb", "# Add initialization content here"
  78       end
  79     end
  80
  81  * Extend `Rails::Generators::Base`.
  82  * Each public method in the generator is executed when a generator is invoked.
  83
  84 ### Generating a generator
  85
  86     $ rails generate generator initializer
  87
  88 ### NamedBase
  89
  90 Use `NamedBase` instead if you want to take an argument. It will be available as
  91 `file_name`.
  92
  93     class InitializerGenerator < Rails::Generators::Base
  94       def lol
  95         puts file_name
  96       end
  97     end
  98
  99 ### More
 100
 101     class InitializerGenerator < Rails::Generators::NamedBase
 102       #
 103       source_root File.expand_path("../templates", __FILE__)
 104       desc "Description goes here."
 105     end
 106
 107 ### Generators lookup
 108
 109 When invoking `rails g XXX`:
 110
 111     [rails/]generators/XXX/XXX_generator.rb
 112     [rails/]generators/XXX_generator.rb
 113
 114 When invoking `rails g XXX:YYY`:
 115
 116     [rails/]generators/XXX/YYY_generator.rb
 117
 118 ActiveModel 'acts as'
 119 ---------------------
 120
 121     # yaffle/lib/yaffle/acts_as_yaffle.rb
 122     module Yaffle
 123       module ActsAsYaffle
 124         extend ActiveSupport::Concern
 125
 126         included do
 127         end
 128
 129         module ClassMethods
 130           def acts_as_yaffle(options = {})
 131             # your code will go here
 132           end
 133         end
 134       end
 135     end
 136
 137     ActiveRecord::Base.send :include, Yaffle::ActsAsYaffle
 138