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 a parameter on initialization of ShowExceptions. Every time there is an exception, ShowExceptions will store the exception in env["action_dispatch.exception"], rewrite the PATH_INFO to the exception status code and call the Rack app.
In Rails applications, the exceptions app can be configured with config.exceptions_app, which defaults to ActionDispatch::PublicExceptions.
If the application returns an "X-Cascade" => "pass" response, this middleware will send an empty response as a 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)
📝 Source code
# File actionpack/lib/action_dispatch/middleware/show_exceptions.rb, line 22
def initialize(app, exceptions_app)
@app = app
@exceptions_app = exceptions_app
endInstance Public methods
call(env)
📝 Source code
# File actionpack/lib/action_dispatch/middleware/show_exceptions.rb, line 27
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