class ActionDispatch::ShowExceptions

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.

Constants

FAILSAFE_RESPONSE

Public Class Methods

new(app, exceptions_app) click to toggle source
# File lib/action_dispatch/middleware/show_exceptions.rb, line 26
def initialize(app, exceptions_app)
  @app = app
  @exceptions_app = exceptions_app
end

Public Instance Methods

call(env) click to toggle source
# File lib/action_dispatch/middleware/show_exceptions.rb, line 31
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

Private Instance Methods

pass_response(status) click to toggle source
# File lib/action_dispatch/middleware/show_exceptions.rb, line 59
def pass_response(status)
  [status, { "Content-Type" => "text/html; charset=#{Response.default_charset}", "Content-Length" => "0" }, []]
end
render_exception(request, exception) click to toggle source
# File lib/action_dispatch/middleware/show_exceptions.rb, line 43
def render_exception(request, exception)
  backtrace_cleaner = request.get_header "action_dispatch.backtrace_cleaner"
  wrapper = ExceptionWrapper.new(backtrace_cleaner, exception)
  status  = wrapper.status_code
  request.set_header "action_dispatch.exception", wrapper.unwrapped_exception
  request.set_header "action_dispatch.original_path", request.path_info
  request.set_header "action_dispatch.original_request_method", request.raw_request_method
  request.path_info = "/#{status}"
  request.request_method = "GET"
  response = @exceptions_app.call(request.env)
  response[1]["X-Cascade"] == "pass" ? pass_response(status) : response
rescue Exception => failsafe_error
  $stderr.puts "Error during failsafe response: #{failsafe_error}\n  #{failsafe_error.backtrace * "\n  "}"
  FAILSAFE_RESPONSE
end