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, :secrets]

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, 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

Returns a new instance of Application.


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# File 'railties/lib/rails/application.rb', line 125

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

  # are these actually used?
  @initial_variable_values = initial_variable_values
  @block = block
end

Instance Attribute Details

#assetsObject

Returns the value of attribute assets


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# File 'railties/lib/rails/application.rb', line 116

def assets
  @assets
end

#reloadersObject (readonly)

Returns the value of attribute reloaders


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# File 'railties/lib/rails/application.rb', line 118

def reloaders
  @reloaders
end

#sandboxObject Also known as: sandbox?

Returns the value of attribute sandbox


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# File 'railties/lib/rails/application.rb', line 116

def sandbox
  @sandbox
end

Class Method Details

.add_lib_to_load_path!(root) ⇒ 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.


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# File 'railties/lib/rails/application.rb', line 319

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

.create(initial_variable_values = {}, &block) ⇒ Object


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

def create(initial_variable_values = {}, &block)
  new(initial_variable_values, &block).run_load_hooks!
end

.find_root(from) ⇒ Object


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# File 'railties/lib/rails/application.rb', line 104

def find_root(from)
  find_root_with_flag "config.ru", from, Dir.pwd
end

.inherited(base) ⇒ Object


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

def inherited(base)
  super
  Rails.app_class = base
  add_lib_to_load_path!(find_root(base.called_from))
  ActiveSupport.run_load_hooks(:before_configuration, base)
end

.instanceObject


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# File 'railties/lib/rails/application.rb', line 96

def instance
  super.run_load_hooks!
end

Instance Method Details

#call(env) ⇒ Object

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


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# File 'railties/lib/rails/application.rb', line 162

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

#configObject

:nodoc:


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# File 'railties/lib/rails/application.rb', line 363

def config #:nodoc:
  @config ||= Application::Configuration.new(self.class.find_root(self.class.called_from))
end

#config=(configuration) ⇒ Object

:nodoc:


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# File 'railties/lib/rails/application.rb', line 367

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

#config_for(name) ⇒ Object

Convenience for loading config/foo.yml for the current Rails env.

Example:

# config/exception_notification.yml:
production:
  url: http://127.0.0.1:8080
  namespace: my_app_production
development:
  url: http://localhost:3001
  namespace: my_app_development

# config/production.rb
Rails.application.configure do
  config.middleware.use ExceptionNotifier, config_for(:exception_notification)
end

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# File 'railties/lib/rails/application.rb', line 227

def config_for(name)
  yaml = Pathname.new("#{paths["config"].existent.first}/#{name}.yml")

  if yaml.exist?
    require "erb"
    (YAML.load(ERB.new(yaml.read).result) || {})[Rails.env] || {}
  else
    raise "Could not load configuration. No such file - #{yaml}"
  end
rescue Psych::SyntaxError => e
  raise "YAML syntax error occurred while parsing #{yaml}. " \
    "Please note that YAML must be consistently indented using spaces. Tabs are not allowed. " \
    "Error: #{e.message}"
end

#console(&blk) ⇒ Object

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


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# File 'railties/lib/rails/application.rb', line 289

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

#env_configObject

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


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# File 'railties/lib/rails/application.rb', line 244

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" => secrets.secret_token,
      "action_dispatch.secret_key_base" => secrets.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,
      "action_dispatch.cookies_serializer" => config.action_dispatch.cookies_serializer,
      "action_dispatch.cookies_digest" => config.action_dispatch.cookies_digest
    })
  end
end

#generators(&blk) ⇒ Object

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


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# File 'railties/lib/rails/application.rb', line 295

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

#helpers_pathsObject

:nodoc:


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# File 'railties/lib/rails/application.rb', line 413

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


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# File 'railties/lib/rails/application.rb', line 350

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.

Returns:

  • (Boolean)

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# File 'railties/lib/rails/application.rb', line 142

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.


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

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

#initializersObject

:nodoc:


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# File 'railties/lib/rails/application.rb', line 357

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.


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# File 'railties/lib/rails/application.rb', line 300

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

#key_generatorObject

Return the application's KeyGenerator


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# File 'railties/lib/rails/application.rb', line 174

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 ||=
    if secrets.secret_key_base
      key_generator = ActiveSupport::KeyGenerator.new(secrets.secret_key_base, iterations: 1000)
      ActiveSupport::CachingKeyGenerator.new(key_generator)
    else
      ActiveSupport::LegacyKeyGenerator.new(secrets.secret_token)
    end
end

#message_verifier(verifier_name) ⇒ Object

Returns a message verifier object.

This verifier can be used to generate and verify signed messages in the application.

It is recommended not to use the same verifier for different things, so you can get different verifiers passing the verifier_name argument.

Parameters

  • verifier_name - the name of the message verifier.

Examples

message = Rails.application.message_verifier('sensitive_data').generate('my sensible data')
Rails.application.message_verifier('sensitive_data').verify(message)# => 'my sensible data'

See the ActiveSupport::MessageVerifier documentation for more information.


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# File 'railties/lib/rails/application.rb', line 204

def message_verifier(verifier_name)
  @message_verifiers[verifier_name] ||= begin
    secret = key_generator.generate_key(verifier_name.to_s)
    ActiveSupport::MessageVerifier.new(secret)
  end
end

#migration_railtiesObject

Return an array of railties respecting the order they're loaded and the order specified by the railties_order config.

While when running initializers we need engines in reverse order here when copying migrations from railties we need then in the same order as given by railties_order


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# File 'railties/lib/rails/application.rb', line 442

def migration_railties # :nodoc:
  ordered_railties.flatten - [self]
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.


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

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

#reload_routes!Object

Reload application routes regardless if they changed or not.


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# File 'railties/lib/rails/application.rb', line 169

def reload_routes!
  routes_reloader.reload!
end

#require_environment!Object

:nodoc:


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# File 'railties/lib/rails/application.rb', line 326

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

#routes_reloaderObject

:nodoc:


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# File 'railties/lib/rails/application.rb', line 331

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

#run_load_hooks!Object

:nodoc:


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# File 'railties/lib/rails/application.rb', line 146

def run_load_hooks! # :nodoc:
  return self if @ran_load_hooks
  @ran_load_hooks = true

  @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
  self
end

#runner(&blk) ⇒ Object

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


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# File 'railties/lib/rails/application.rb', line 283

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

#secretsObject

Returns secrets added to config/secrets.yml.

Example:

development:
  secret_key_base: 836fa3665997a860728bcb9e9a1e704d427cfc920e79d847d79c8a9a907b9e965defa4154b2b86bdec6930adbe33f21364523a6f6ce363865724549fdfc08553
test:
  secret_key_base: 5a37811464e7d378488b0f073e2193b093682e4e21f5d6f3ae0a4e1781e61a351fdc878a843424e81c73fb484a40d23f92c8dafac4870e74ede6e5e174423010
production:
  secret_key_base: <%= ENV["SECRET_KEY_BASE"] %>
  namespace: my_app_production

Rails.application.secrets.namespace returns my_app_production in the production environment.


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# File 'railties/lib/rails/application.rb', line 385

def secrets
  @secrets ||= begin
    secrets = ActiveSupport::OrderedOptions.new
    yaml = config.paths["config/secrets"].first
    if File.exist?(yaml)
      require "erb"
      all_secrets = YAML.load(ERB.new(IO.read(yaml)).result) || {}
      env_secrets = all_secrets[Rails.env]
      secrets.merge!(env_secrets.symbolize_keys) if env_secrets
    end

    # Fallback to config.secret_key_base if secrets.secret_key_base isn't set
    secrets.secret_key_base ||= config.secret_key_base    # Fallback to config.secret_token if secrets.secret_token isn't set

    secrets.secret_token ||= config.secret_token

    secrets
  end
end

#secrets=(secrets) ⇒ Object

:nodoc:


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# File 'railties/lib/rails/application.rb', line 405

def secrets=(secrets) #:nodoc:
  @secrets = secrets
end

#to_appObject

:nodoc:


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# File 'railties/lib/rails/application.rb', line 409

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.


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# File 'railties/lib/rails/application.rb', line 338

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