This middleware rescues any exception returned by the application and calls an exceptions app that will wrap it in a format for the end user.

The exceptions app should be passed as parameter on initialization of ShowExceptions. Every time there is an exception, ShowExceptions will store the exception in env, rewrite the PATH_INFO to the exception status code and call the Rack app.

If the application returns a “X-Cascade” pass response, this middleware will send an empty response as result with the correct status code. If any exception happens inside the exceptions app, this middleware catches the exceptions and returns a failsafe response.

Methods

Class Public methods

new(app, exceptions_app)

# File actionpack/lib/action_dispatch/middleware/show_exceptions.rb, line 19
def initialize(app, exceptions_app)
  @app = app
  @exceptions_app = exceptions_app
end

Instance Public methods

call(env)

# File actionpack/lib/action_dispatch/middleware/show_exceptions.rb, line 24
def call(env)
  request = ActionDispatch::Request.new env
  @app.call(env)
rescue Exception => exception
  if request.show_exceptions?
    render_exception(request, exception)
  else
    raise exception
  end
end