Refactoring a PHP application, part 1

29 Jun 2014

This is the first post in the series. The second post is available here.

There's been a refreshing wave of change in the way we build web applications in PHP over the last few years. The advent of Composer and the wave of modular, reusable components it's brought us have dramatically improved the architecture of new applications. Unfortunately for the developers forced to maintain them, not all applications are taking advantage of these new and powerful tools. In this series I'll be discussing the process of upgrading and refactoring a typical "old school" site built with PHP into a solid, well tested application.

Let's first discuss what we're working with. I'm assuming a multipage site with multiple entry points. The ones I've seen and worked with tend to have lines like include "inc/header.php". There's frequently code that's been copied and pasted in multiple places, and these snippets often have minute and unmarked differences. There's rarely any form of testing or build process, and the business login is often intertwined with the display login.

Note: this process is not specific to PHP or even to sites structured like this, but for simplicity's sake (and because of how often I see sites like this in the wild) this is the base we'll be working from.

Now that we know what we're working with, let's establish what we'd like to end up with:

• A single entry point (index.php) in the public web directory

• A full set of tests, both unit and functional, that insure the site is functioning correctly at all times

• A modern deployment process, using Docker, Nginx, and PHP-FPM

• A way of interacting with the code from the command line effectively. Any HTTP request should be able to be perfectly simulated from any SAPI (cli, phpdbg, etc.)

Let's begin.