rails-plugins.md

   1 ---
   2 title: Rails plugins
   3 category: Rails
   4 layout: 2017/sheet
   5 ---
   6
   7 ### Generate a plugin
   8
   9 Generate a Rails Engine plugin:
  10
  11     rails plugin new myplugin --skip-bundle --full
  12
  13 Initializers
  14 ------------
  15
  16 ### Initializers
  17
  18 * [Rails::Railtie](http://edgeapi.rubyonrails.org/classes/Rails/Railtie.html)
  19 * [EngineYard blog
  20   post](http://www.engineyard.com/blog/2010/extending-rails-3-with-railties/)
  21
  22 ### Initializer method
  23
  24 Subclass Railtie and provide an `initializer` method.
  25
  26     module NewPlugin
  27       class Railtie < Rails::Railtie
  28         initializer "newplugin.initialize" do |app|
  29
  30           # subscribe to all rails notifications: controllers, AR, etc.
  31           ActiveSupport::Notifications.subscribe do |*args|
  32             event = ActiveSupport::Notifications::Event.new(*args)
  33             puts "Got notification: #{event.inspect}"
  34           end
  35
  36         end
  37       end
  38     end
  39
  40 Custom routes
  41 -------------
  42
  43 ### Custom routes
  44
  45 * [ActionDispatch::Routing::Mapper](http://api.rubyonrails.org/classes/ActionDispatch/Routing/Mapper.html)
  46
  47 ### Creating routes
  48
  49 To create custom `routes.rb` keywords:
  50
  51     # # routes.rb:
  52     # myplugin_for x
  53     #
  54     class ActionDispatch::Routing
  55       class Mapper
  56         def myplugin_for(*x)
  57         end
  58       end
  59     end
  60
  61 Example with a block:
  62
  63     # authenticated do
  64     #   resources :users
  65     # end
  66     #
  67     def authenticated
  68       constraint = lambda { |request| request... }
  69
  70       constraints(constraint) { yield }
  71     end
  72
  73 Custom generators
  74 -----------------
  75
  76 ### Custom generators
  77
  78 * [Guide: generators](http://guides.rubyonrails.org/generators.html)
  79 * [ActiveRecord::Generators::Base](http://api.rubyonrails.org/classes/ActiveRecord/Generators/Base.html)
  80
  81 ### Basic
  82
  83     # rails g initializer
  84     # lib/generators/initializer_generator.rb
  85     class InitializerGenerator < Rails::Generators::Base
  86       def create_initializer_file
  87         create_file "config/initializers/initializer.rb", "# Add initialization content here"
  88       end
  89     end
  90
  91  * Extend `Rails::Generators::Base`.
  92  * Each public method in the generator is executed when a generator is invoked.
  93
  94 ### Generating a generator
  95
  96     $ rails generate generator initializer
  97
  98 ### NamedBase
  99
 100 Use `NamedBase` instead if you want to take an argument. It will be available as
 101 `file_name`.
 102
 103     class InitializerGenerator < Rails::Generators::Base
 104       def lol
 105         puts file_name
 106       end
 107     end
 108
 109 ### More
 110
 111     class InitializerGenerator < Rails::Generators::NamedBase
 112       #
 113       source_root File.expand_path("../templates", __FILE__)
 114       desc "Description goes here."
 115     end
 116
 117 ### Generators lookup
 118
 119 When invoking `rails g XXX`:
 120
 121     [rails/]generators/XXX/XXX_generator.rb
 122     [rails/]generators/XXX_generator.rb
 123
 124 When invoking `rails g XXX:YYY`:
 125
 126     [rails/]generators/XXX/YYY_generator.rb
 127
 128 ActiveModel 'acts as'
 129 ---------------------
 130
 131 ### acts as
 132
 133     # yaffle/lib/yaffle/acts_as_yaffle.rb
 134     module Yaffle
 135       module ActsAsYaffle
 136         extend ActiveSupport::Concern
 137
 138         included do
 139         end
 140
 141         module ClassMethods
 142           def acts_as_yaffle(options = {})
 143             # your code will go here
 144           end
 145         end
 146       end
 147     end
 148
 149     ActiveRecord::Base.send :include, Yaffle::ActsAsYaffle
 150