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Class: Rails::Application

Overview

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

Initialization

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

Configuration

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

Check 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 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 application, then you must run those these manually.

Constant Summary

Railtie - Inherited

ABSTRACT_RAILTIES

Class Attribute Summary

Engine - Inherited

.called_from,
.isolated?

Alias for Engine.isolated.

Railtie - Inherited

.abstract_railtie?

Class Method Summary

Engine - Inherited

.endpoint, .engine_name,
.find

Finds engine with given path.
.find_root, .inherited, .isolate_namespace, .isolated, .new

Railtie - Inherited

.configure

Allows you to configure the railtie.
.console, .generators, .inherited,
.instance

Since Railtie cannot be instantiated, any methods that call instance are intended to be called only on subclasses of a Railtie.
.new, .railtie_name, .rake_tasks, .respond_to_missing?, .runner, .subclasses

Instance Attribute Summary

Engine - Inherited

#engine_name, #middleware, #paths, #root,
#routes

Defines the routes for this engine.

Railtie - Inherited

#config, #railtie_name

Instance Method Summary

Engine - Inherited

#app

Returns the underlying rack application for this engine.
#call

Define the Rack API for this engine.
#config

Define the configuration object for the engine.
#eager_load!

Eager load the application by loading all ruby files inside eager_load paths.
#endpoint

Returns the endpoint for this engine.
#env_config

Defines additional Rack env configuration that is added on each call.
#helpers

Returns a module with all the helpers defined for the engine.
#helpers_paths

Returns all registered helpers paths.
#isolated?,
#load_console

Load console and invoke the registered hooks.
#load_generators

Load Rails generators and invoke the registered hooks.
#load_runner

Load Rails runner and invoke the registered hooks.
#load_seed

Load data from db/seeds.rb file.
#load_tasks

Load Rake, railties tasks and invoke the registered hooks.
#railties

Railtie - Inherited

#configure, #railtie_namespace

Initializable - Included

#initializers, #run_initializers

Constructor Details

.new(initial_variable_values = {}, &block) ⇒ Application

[ GitHub ] 

  


# 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


  







Class Method Details



  

    .create(initial_variable_values = {}, &block)  
  

  [ GitHub ]


  

  


# 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)  
  

  [ GitHub ]


  

  


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



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


  








  

    .inherited(base)  
  

  [ GitHub ]


  

  


# 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


  








  

    .instance  
  

  [ GitHub ]


  

  


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



def instance
  super.run_load_hooks!
end


  







Instance Attribute Details



  

    #assets   (rw)
  

  [ GitHub ]


  

  


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



attr_accessor :assets, :sandbox


  








  

    #default_url_options   (rw)
  

  [ GitHub ]


  

  


# File 'railties/lib/rails/application.rb', line 120



delegate :default_url_options, :default_url_options=, to: :routes


  








  

    #initialized?  ⇒ Boolean  (readonly)
  



  

    

Returns true if the application is initialized.


  





  


  [ GitHub ]


  

  


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



def initialized?
  @initialized
end


  








  

    #reloaders   (readonly)
  

  [ GitHub ]


  

  


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



attr_reader :reloaders


  








  

    #sandbox?   (rw)
  



  

    

Alias for #sandbox.


  



  [ GitHub ]


  

  


# File 'railties/lib/rails/application.rb', line 117



alias_method :sandbox?, :sandbox


  








  

    #secrets   (rw)
  



  

    

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.


  



  [ GitHub ]


  

  


# 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


  







Instance Method Details



  

    #call(env)  
  



  

    

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


  



  [ GitHub ]


  

  


# 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


  








  

    #config_for(name)  
  



  

    

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


  



  [ GitHub ]


  

  


# 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)  
  



  

    

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


  



  [ GitHub ]


  

  


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



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


  








  

    #env_config  
  



  

    

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


  



  [ GitHub ]


  

  


# 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)  
  



  

    

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


  



  [ GitHub ]


  

  


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



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


  








  

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



  

    

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


  



  [ GitHub ]


  

  


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



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


  








  

    #isolate_namespace(mod)  
  



  

    

Sends the isolate_namespace method up to the class method.


  



  [ GitHub ]


  

  


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



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


  








  

    #key_generator  
  



  

    

Return the application's KeyGenerator


  



  [ GitHub ]


  

  


# 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)  
  



  

    

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.


  



  [ GitHub ]


  

  


# 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


  








  

    #rake_tasks(&block)  
  



  

    

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.


  



  [ GitHub ]


  

  


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



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


  








  

    #reload_routes!  
  



  

    

Reload application routes regardless if they changed or not.


  



  [ GitHub ]


  

  


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



def reload_routes!
  routes_reloader.reload!
end


  








  

    #runner(&blk)  
  



  

    

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


  



  [ GitHub ]


  

  


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



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


  








  

    #sandbox   (rw)
    Also known as: #sandbox?
  

  [ GitHub ]


  

  


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



attr_accessor :assets, :sandbox