V2.2: Rendering errors

When running your app in production mode, error views will be rendered for any uncaught exceptions. This allows you to present a helpful error screen to your users while also hiding any technical details of the error.

These error views are static HTML only. You can find them in your app’s public/ directory, at 404.html and 500.html.

You can customize these views however you wish, though you should be mindful to keep their content static and self-contained to the HTML file as much as possible.

Customizing error views

You can enable or disable these error views using the config.render_errors app setting. This defaults to true when your app is in production mode, and false for all other modes.

To configure which error views show for which exceptions, use the config.render_error_responses setting. This is a hash that maps string representations of Ruby exception classes to the symbolized form (downcased, underscored) of Rack’s list of HTTP error names. These names are then mapped to the equivalent status codes and used to locate the HTML files in public/.

# config/app.rb

module Bookshelf
  class App < Hanami::App
    config.render_error_responses.merge!(
      "ROM::TupleCountMismatchError" => :not_found
    )
  end
end