Class: Rails::Application

Inherits:
Engine show all
Defined in:
railties/lib/rails/application.rb,
railties/lib/rails/application/finisher.rb,
railties/lib/rails/application/bootstrap.rb,
railties/lib/rails/application/configuration.rb,
railties/lib/rails/application/routes_reloader.rb,
railties/lib/rails/application/default_middleware_stack.rb

Overview

In Rails 3.0, a Rails::Application object was introduced which is nothing more than an Engine but with the responsibility of coordinating the whole boot process.

Initialization

Rails::Application is responsible for executing all railties and engines initializers. It also executes some bootstrap initializers (check Rails::Application::Bootstrap) and finishing initializers, after all the others are executed (check Rails::Application::Finisher).

Configuration

Besides providing the same configuration as Rails::Engine and Rails::Railtie, the application object has several specific configurations, for example “cache_classes”, “consider_all_requests_local”, “filter_parameters”, “logger” and so forth.

Check Rails::Application::Configuration to see them all.

Routes

The application object is also responsible for holding the routes and reloading routes whenever the files change in development.

Middlewares

The Application is also responsible for building the middleware stack.

Booting process

The application is also responsible for setting up and executing the booting process. From the moment you require “config/application.rb” in your app, the booting process goes like this:

1)  require "config/boot.rb" to setup load paths
2)  require railties and engines
3)  Define Rails.application as "class MyApp::Application < Rails::Application"
4)  Run config.before_configuration callbacks
5)  Load config/environments/ENV.rb
6)  Run config.before_initialize callbacks
7)  Run Railtie#initializer defined by railties, engines and application.
    One by one, each engine sets up its load paths, routes and runs its config/initializers/* files.
8)  Custom Railtie#initializers added by railties, engines and applications are executed
9)  Build the middleware stack and run to_prepare callbacks
10) Run config.before_eager_load and eager_load! if eager_load is true
11) Run config.after_initialize callbacks

Multiple Applications

If you decide to define multiple applications, then the first application that is initialized will be set to Rails.application, unless you override it with a different application.

To create a new application, you can instantiate a new instance of a class that has already been created:

class Application < Rails::Application
end

first_application  = Application.new
second_application = Application.new(config: first_application.config)

In the above example, the configuration from the first application was used to initialize the second application. You can also use the initialize_copy on one of the applications to create a copy of the application which shares the configuration.

If you decide to define rake tasks, runners, or initializers in an application other than Rails.application, then you must run those these manually.

Defined Under Namespace

Modules: Bootstrap, Finisher Classes: Configuration, DefaultMiddlewareStack, RoutesReloader

Constant Summary collapse

INITIAL_VARIABLES =
[:config, :railties, :routes_reloader, :reloaders,
:routes, :helpers, :app_env_config]

Constants inherited from Railtie

Railtie::ABSTRACT_RAILTIES

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from Engine

#app, #eager_load!, endpoint, #endpoint, find, #helpers, isolate_namespace, #load_console, #load_generators, #load_runner, #load_seed, #load_tasks, #railties, #routes, #routes?

Methods inherited from Railtie

abstract_railtie?, #configure, configure, console, generators, instance, railtie_name, #railtie_namespace, rake_tasks, respond_to_missing?, runner, subclasses

Methods included from Initializable

included, #run_initializers

Constructor Details

#initialize(initial_variable_values = {}, &block) ⇒ Application


108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
# File 'railties/lib/rails/application.rb', line 108

def initialize(initial_variable_values = {}, &block)
  super()
  @initialized      = false
  @reloaders        = []
  @routes_reloader  = nil
  @app_env_config   = nil
  @ordered_railties = nil
  @railties         = nil

  add_lib_to_load_path!
  ActiveSupport.run_load_hooks(:before_configuration, self)

  initial_variable_values.each do |variable_name, value|
    if INITIAL_VARIABLES.include?(variable_name)
      instance_variable_set("@#{variable_name}", value)
    end
  end

  instance_eval(&block) if block_given?
end

Instance Attribute Details

#assetsObject

Returns the value of attribute assets


99
100
101
# File 'railties/lib/rails/application.rb', line 99

def assets
  @assets
end

#reloadersObject (readonly)

Returns the value of attribute reloaders


101
102
103
# File 'railties/lib/rails/application.rb', line 101

def reloaders
  @reloaders
end

#sandboxObject Also known as: sandbox?

Returns the value of attribute sandbox


99
100
101
# File 'railties/lib/rails/application.rb', line 99

def sandbox
  @sandbox
end

Class Method Details

.inherited(base) ⇒ Object


86
87
88
89
# File 'railties/lib/rails/application.rb', line 86

def inherited(base)
  super
  Rails.application ||= base.instance
end

Instance Method Details

#add_lib_to_load_path!Object

This method is called just after an application inherits from Rails::Application, allowing the developer to load classes in lib and use them during application configuration.

class MyApplication < Rails::Application
  require "my_backend" # in lib/my_backend
  config.i18n.backend = MyBackend
end

Notice this method takes into consideration the default root path. So if you are changing config.root inside your application definition or having a custom Rails application, you will need to add lib to $LOAD_PATH on your own in case you need to load files in lib/ during the application configuration as well.


224
225
226
227
228
229
# File 'railties/lib/rails/application.rb', line 224

def add_lib_to_load_path! #:nodoc:
  path = File.join config.root, 'lib'
  if File.exists?(path) && !$LOAD_PATH.include?(path)
    $LOAD_PATH.unshift(path)
  end
end

#call(env) ⇒ Object

Implements call according to the Rack API. It simply dispatches the request to the underlying middleware stack.


136
137
138
139
140
# File 'railties/lib/rails/application.rb', line 136

def call(env)
  env["ORIGINAL_FULLPATH"] = build_original_fullpath(env)
  env["ORIGINAL_SCRIPT_NAME"] = env["SCRIPT_NAME"]
  super(env)
end

#configObject

:nodoc:


268
269
270
# File 'railties/lib/rails/application.rb', line 268

def config #:nodoc:
  @config ||= Application::Configuration.new(find_root_with_flag("config.ru", Dir.pwd))
end

#config=(configuration) ⇒ Object

:nodoc:


272
273
274
# File 'railties/lib/rails/application.rb', line 272

def config=(configuration) #:nodoc:
  @config = configuration
end

#env_configObject

Stores some of the Rails initial environment parameters which will be used by middlewares and engines to configure themselves.


163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
# File 'railties/lib/rails/application.rb', line 163

def env_config
  @app_env_config ||= begin
    validate_secret_key_config!

    super.merge({
      "action_dispatch.parameter_filter" => config.filter_parameters,
      "action_dispatch.redirect_filter" => config.filter_redirect,
      "action_dispatch.secret_token" => config.secret_token,
      "action_dispatch.secret_key_base" => config.secret_key_base,
      "action_dispatch.show_exceptions" => config.action_dispatch.show_exceptions,
      "action_dispatch.show_detailed_exceptions" => config.consider_all_requests_local,
      "action_dispatch.logger" => Rails.logger,
      "action_dispatch.backtrace_cleaner" => Rails.backtrace_cleaner,
      "action_dispatch.key_generator" => key_generator,
      "action_dispatch.http_auth_salt" => config.action_dispatch.http_auth_salt,
      "action_dispatch.signed_cookie_salt" => config.action_dispatch.signed_cookie_salt,
      "action_dispatch.encrypted_cookie_salt" => config.action_dispatch.encrypted_cookie_salt,
      "action_dispatch.encrypted_signed_cookie_salt" => config.action_dispatch.encrypted_signed_cookie_salt
    })
  end
end

#helpers_pathsObject

:nodoc:


280
281
282
# File 'railties/lib/rails/application.rb', line 280

def helpers_paths #:nodoc:
  config.helpers_paths
end

#initialize!(group = :default) ⇒ Object

Initialize the application passing the given group. By default, the group is :default


255
256
257
258
259
260
# File 'railties/lib/rails/application.rb', line 255

def initialize!(group=:default) #:nodoc:
  raise "Application has been already initialized." if @initialized
  run_initializers(group, self)
  @initialized = true
  self
end

#initialized?Boolean

Returns true if the application is initialized.


130
131
132
# File 'railties/lib/rails/application.rb', line 130

def initialized?
  @initialized
end

#initializer(name, opts = {}, &block) ⇒ Object

Sends the initializers to the initializer method defined in the Rails::Initializable module. Each Rails::Application class has its own set of initializers, as defined by the Initializable module.


194
195
196
# File 'railties/lib/rails/application.rb', line 194

def initializer(name, opts={}, &block)
  self.class.initializer(name, opts, &block)
end

#initializersObject

:nodoc:


262
263
264
265
266
# File 'railties/lib/rails/application.rb', line 262

def initializers #:nodoc:
  Bootstrap.initializers_for(self) +
  railties_initializers(super) +
  Finisher.initializers_for(self)
end

#isolate_namespace(mod) ⇒ Object

Sends the isolate_namespace method up to the class method.


205
206
207
# File 'railties/lib/rails/application.rb', line 205

def isolate_namespace(mod)
  self.class.isolate_namespace(mod)
end

#key_generatorObject

Return the application's KeyGenerator


148
149
150
151
152
153
154
155
156
157
158
159
# File 'railties/lib/rails/application.rb', line 148

def key_generator
  # number of iterations selected based on consultation with the google security
  # team. Details at https://github.com/rails/rails/pull/6952#issuecomment-7661220
  @caching_key_generator ||= begin
    if config.secret_key_base
      key_generator = ActiveSupport::KeyGenerator.new(config.secret_key_base, iterations: 1000)
      ActiveSupport::CachingKeyGenerator.new(key_generator)
    else
      ActiveSupport::LegacyKeyGenerator.new(config.secret_token)
    end
  end
end

#rake_tasks(&block) ⇒ Object

If you try to define a set of rake tasks on the instance, these will get passed up to the rake tasks defined on the application's class.


187
188
189
# File 'railties/lib/rails/application.rb', line 187

def rake_tasks(&block)
  self.class.rake_tasks(&block)
end

#reload_routes!Object

Reload application routes regardless if they changed or not.


143
144
145
# File 'railties/lib/rails/application.rb', line 143

def reload_routes!
  routes_reloader.reload!
end

#require_environment!Object

:nodoc:


231
232
233
234
# File 'railties/lib/rails/application.rb', line 231

def require_environment! #:nodoc:
  environment = paths["config/environment"].existent.first
  require environment if environment
end

#routes_reloaderObject

:nodoc:


236
237
238
# File 'railties/lib/rails/application.rb', line 236

def routes_reloader #:nodoc:
  @routes_reloader ||= RoutesReloader.new
end

#runner(&blk) ⇒ Object

Sends any runner called in the instance of a new application up to the runner method defined in Rails::Railtie.


200
201
202
# File 'railties/lib/rails/application.rb', line 200

def runner(&blk)
  self.class.runner(&blk)
end

#to_appObject

:nodoc:


276
277
278
# File 'railties/lib/rails/application.rb', line 276

def to_app #:nodoc:
  self
end

#watchable_argsObject

Returns an array of file paths appended with a hash of directories-extensions suitable for ActiveSupport::FileUpdateChecker API.


243
244
245
246
247
248
249
250
251
# File 'railties/lib/rails/application.rb', line 243

def watchable_args #:nodoc:
  files, dirs = config.watchable_files.dup, config.watchable_dirs.dup

  ActiveSupport::Dependencies.autoload_paths.each do |path|
    dirs[path.to_s] = [:rb]
  end

  [files, dirs]
end