The application builder allows you to override elements of the application generator without being forced to reverse the operations of the default generator.

This allows you to override entire operations, like the creation of the Gemfile, README, or JavaScript files, without needing to know exactly what those operations do so you can create another template action.

class CustomAppBuilder < Rails::AppBuilder
  def test
    @generator.gem "rspec-rails", group: [:development, :test]
    run "bundle install"
    generate "rspec:install"
  end
end
Methods
A
B
C
D
G
L
P
R
S
T
V
Instance Public methods
app()
# File rails/railties/lib/rails/generators/rails/app/app_generator.rb, line 70
def app
  directory "app"

  keep_file "app/assets/images"
  empty_directory_with_keep_file "app/assets/javascripts/channels" unless options[:skip_action_cable]

  keep_file  "app/controllers/concerns"
  keep_file  "app/models/concerns"
end
bin()
# File rails/railties/lib/rails/generators/rails/app/app_generator.rb, line 80
def bin
  directory "bin" do |content|
    "#{shebang}\n" + content
  end
  chmod "bin", 0755 & ~File.umask, verbose: false
end
bin_when_updating()
# File rails/railties/lib/rails/generators/rails/app/app_generator.rb, line 87
def bin_when_updating
  bin_yarn_exist = File.exist?("bin/yarn")

  bin

  if options[:api] && !bin_yarn_exist
    remove_file "bin/yarn"
  end
end
config()
# File rails/railties/lib/rails/generators/rails/app/app_generator.rb, line 97
def config
  empty_directory "config"

  inside "config" do
    template "routes.rb"
    template "application.rb"
    template "environment.rb"
    template "secrets.yml"
    template "cable.yml" unless options[:skip_action_cable]
    template "puma.rb"   unless options[:skip_puma]
    template "spring.rb" if spring_install?

    directory "environments"
    directory "initializers"
    directory "locales"
  end
end
config_when_updating()
# File rails/railties/lib/rails/generators/rails/app/app_generator.rb, line 115
def config_when_updating
  cookie_serializer_config_exist = File.exist?("config/initializers/cookies_serializer.rb")
  action_cable_config_exist = File.exist?("config/cable.yml")
  rack_cors_config_exist = File.exist?("config/initializers/cors.rb")
  assets_config_exist = File.exist?("config/initializers/assets.rb")
  new_framework_defaults_5_1_exist = File.exist?("config/initializers/new_framework_defaults_5_1.rb")

  config

  unless cookie_serializer_config_exist
    gsub_file "config/initializers/cookies_serializer.rb", /json(?!,)/, "marshal"
  end

  unless action_cable_config_exist
    template "config/cable.yml"
  end

  unless rack_cors_config_exist
    remove_file "config/initializers/cors.rb"
  end

  if options[:api]
    unless cookie_serializer_config_exist
      remove_file "config/initializers/cookies_serializer.rb"
    end

    unless assets_config_exist
      remove_file "config/initializers/assets.rb"
    end

    # Sprockets owns the only new default for 5.1:
    # In API-only Applications, we don't want the file.
    unless new_framework_defaults_5_1_exist
      remove_file "config/initializers/new_framework_defaults_5_1.rb"
    end
  end
end
configru()
# File rails/railties/lib/rails/generators/rails/app/app_generator.rb, line 56
def configru
  template "config.ru"
end
database_yml()
# File rails/railties/lib/rails/generators/rails/app/app_generator.rb, line 153
def database_yml
  template "config/databases/#{options[:database]}.yml", "config/database.yml"
end
db()
# File rails/railties/lib/rails/generators/rails/app/app_generator.rb, line 157
def db
  directory "db"
end
gemfile()
# File rails/railties/lib/rails/generators/rails/app/app_generator.rb, line 52
def gemfile
  template "Gemfile"
end
gitignore()
# File rails/railties/lib/rails/generators/rails/app/app_generator.rb, line 60
def gitignore
  template "gitignore", ".gitignore"
end
lib()
# File rails/railties/lib/rails/generators/rails/app/app_generator.rb, line 161
def lib
  empty_directory "lib"
  empty_directory_with_keep_file "lib/tasks"
  empty_directory_with_keep_file "lib/assets"
end
log()
# File rails/railties/lib/rails/generators/rails/app/app_generator.rb, line 167
def log
  empty_directory_with_keep_file "log"
end
public_directory()
# File rails/railties/lib/rails/generators/rails/app/app_generator.rb, line 171
def public_directory
  directory "public", "public", recursive: false
end
rakefile()
# File rails/railties/lib/rails/generators/rails/app/app_generator.rb, line 44
def rakefile
  template "Rakefile"
end
readme()
# File rails/railties/lib/rails/generators/rails/app/app_generator.rb, line 48
def readme
  copy_file "README.md", "README.md"
end
system_test()
# File rails/railties/lib/rails/generators/rails/app/app_generator.rb, line 187
def system_test
  empty_directory_with_keep_file "test/system"

  template "test/application_system_test_case.rb"
end
test()
# File rails/railties/lib/rails/generators/rails/app/app_generator.rb, line 175
def test
  empty_directory_with_keep_file "test/fixtures"
  empty_directory_with_keep_file "test/fixtures/files"
  empty_directory_with_keep_file "test/controllers"
  empty_directory_with_keep_file "test/mailers"
  empty_directory_with_keep_file "test/models"
  empty_directory_with_keep_file "test/helpers"
  empty_directory_with_keep_file "test/integration"

  template "test/test_helper.rb"
end
tmp()
# File rails/railties/lib/rails/generators/rails/app/app_generator.rb, line 193
def tmp
  empty_directory_with_keep_file "tmp"
  empty_directory "tmp/cache"
  empty_directory "tmp/cache/assets"
end
vendor()
# File rails/railties/lib/rails/generators/rails/app/app_generator.rb, line 199
def vendor
  empty_directory_with_keep_file "vendor"

  unless options[:skip_yarn]
    template "package.json"
  end
end
version_control()
# File rails/railties/lib/rails/generators/rails/app/app_generator.rb, line 64
def version_control
  if !options[:skip_git] && !options[:pretend]
    run "git init"
  end
end