WebfactoryExceptionsBundle

A bundle to simplify development of your custom, user-friendly Symfony error pages.

Why?

By default, you would need to switch kernel.debug to false (most probably by using the app.php front controller and/or using the prod environment) in order to see the user-facing error pages. But this also requires you to clear the template cache every time you make a change to your error page template. Additionally, you won't get helpful error messages in case something goes wrong.

This bundle provides a simple way to view error pages for different HTTP status codes also in kernel.debug mode, so you can easily design them. It also contains some building blocks to help you get the job done.

Follow the installation steps, view your error pages in action and then learn about the predefined Twig blocks for more user-friendly error pages.

Installation

Step 1) Get the bundle via Composer

Add the following to composer.json (see http://getcomposer.org/):

"require-dev" :  {
    // ...
    "webfactory/exceptions-bundle": "@stable"
}

If you don't have a require-dev key in your composer.json file, just add one! You can alternatively add this to your require key and things will work just fine. Confused about the difference? See: GetComposer.org: require-dev.

Step 2) Enable the bundle in app/AppKernel.php:

<?php
// app/AppKernel.php

public function registerBundles()
{
    // ...
    if (in_array($this->getEnvironment(), array('dev', 'test'))) {
        $bundles[] = new Webfactory\Bundle\ExceptionsBundle\WebfactoryExceptionsBundle();
    }
    // ...
}

Step 3) Import the routing into app/config/routing_dev.yml:

# app/config/routing_dev.yml
webfactory_exceptions:
    resource: "@WebfactoryExceptionsBundle/Resources/config/routing.yml"
    prefix: /_error

Great - now let's have a look at your error pages.

Viewing Your Error Pages

Have you read the Symfony Cookbook section on customizing the 404 page and other error pages? Great! Then you know you should place your custom error page templates in app/Resources/TwigBundle/views/Exception/errorX.html.twig and how Symfony determines which template to use.

Suppose you've just created an error404.html.twig template. To view this error page, go to:

http://localhost/app_dev.php/_error/404

Of course, change http://localhost to the local URL of your app. In fact, you can see the error page for any HTTP status code in any format, thanks to the URL that this bundle gives you:

/_error/{statuscode}/{format}

Predefined Twig Blocks

WebfactoryExceptionsBundle also contains some Twig blocks we find useful to quickly create helpful, user friendly error pages.

Let's say your generic error page extends the base layout of MyWebsiteBundle. Then you may want to have your error.html.twig to look something like this:

{# error.html.twig #}
{% extends 'MyWebsiteBundle:Layout:base.html.twig' %}

{% block myMainContentContainer %}
    {{ block('webfactory_exceptions_standardExceptionPage') }}
{% endblock %}

The webfactory_exceptions_standardExceptionPage block has headings, the translated exception description and provides the user with a list of alternatives what they can do next: get back (simulating a browser back), get to the homepage, get to the contact page or google the domain. It may look like this:

Links to homepage and contact page

A default block in the bundle provides a link to the homepage with the default target /. If your application does not start at /, you need to set the variable homepageUrl.

Also, you may want to set the variable contactUrl to get a link to your contact page in the listed alternatives.

{# error.html.twig #}
{% extends 'MeineWebsiteBundle:Layout:base.html.twig' %}

{% set homepageUrl = "http://www.webfactory.de" %}
{% set contactUrl = path('name_of_a_route') %}

{# your blocks and definitions... #}

Filling in blocks of base layouts

If your base layout already features blocks you need to fill with exception specific content, you can do it this way:

{# error.html.twig #}
{% extends 'MyWebsiteBundle:Layout:base.html.twig' %}

{% use "WebfactoryExceptionsBundle:Exception:blocks.html.twig" with
        webfactory_exceptions_error_title as title,
        webfactory_exceptions_error_headline as stage_headline
%}

This loads the webfactory_exceptions_error_title block directly into the title block of your base layout, as well as the webfactory_exceptions_error_headline block into the stage_headline block.

Happy error-styling!

Credits, Copyright and License

This bundle was started at webfactory GmbH, Bonn. It was inspired by the blog post How Symfony2 turns exceptions into error pages and how to customize those.

• http://www.webfactory.de
• http://twitter.com/webfactory

Copyright 2012-2014 webfactory GmbH, Bonn. Code released under the MIT license.