What are some of the best patterns and practices for PHP development? [closed]

Question

I am mainly looking for good development practices specially when working in conjunction with mysql. I searched through the questions but could not find any related questions. I would appreciate if some one share their practices and wisdom gained through experience.

Apart from some coding standards, I am also looking for design standards and common architectural practices.

Background: I started my career with Java, and over the years I moved to C#/.NET space. I have been practicing architect for over 3 years now. Just added this to give some idea to people.

Answer 1

I would suggest that you familiarize yourself with the history of PHP, I know that doing so has given me a much greater appreciation of what PHP is today and where it has come from.

In short, PHP was written by Rasmus Lerdorf to provide simple wrapper functions for the C code that was actually doing the heavy-lifting so that he could have a simpler language / syntax for writing templates that needed to behave dynamically. The growth of PHP and the community which surrounds it is best described as organic. And much like other things that grow organically, its more than a little messy, asymmetrical, and downright non-congruent.

Once you understand PHP and its community, you need to embrace PHP for everything that it is and everything that it is not. This idea was best presented by Terry Chay in his article PHP without PHP. He's specifically talking about the concept of funky caching, but he captures the concept of coding for PHP as if it were PHP and not (insert favorite language here) better than anyone I've ever seen. In other words, don't try to make PHP into Java, C#, Ruby, etc because if you do you'll fail and you'll hate your life.

Take a look at How is PHP Done the Right Way?.

I must say that you must first, last, and always avoid the tendency of most beginning PHP developers to use the spaghetti-code anti-pattern. In other words, if you find that you're writing code that contains sql queries, manipulation of data, validation of data, and html output all in a single php script, then you're doing it wrong.

In order to avoid this, it will be helpful to learn something about the nature of web-oriented design patterns. This of course precludes a familiarity with object-oriented programming. But once you've learned the basics of object-oriented programming in PHP, study the MVC design pattern. You don't have to implement this exactly but using the basic ideas of Model-View-Controller will allow you to avoid the blob script problem that most newbies tend to create.

On this point, I would strongly recommend that you take any code snippets you find on the web with a grain of salt. And even if you find it in a book you'll have to consider how old the book is. PHP as a language has advanced quite a long ways and you can't just take code samples at face value because, depending on their age, they may be using workarounds that were valid in 3.x or 4.x but simply are no longer necessary with newer features.

One great thing to do is to study the various frameworks out there. Evaluate what you like and what you don't. Maybe even work up each of the quickstarts that are provided with the framework documentation so that you can start to get an idea of what you like and don't like. And I would strongly recommend that you review the code from the frameworks as well as several other open-source projects so that you can get a feel for how others do things in PHP. Again, take it all with a grain of salt because every PHP developer has their own pet peeves and nuances and none of us is right all the time. In fact, most of the time with PHP there are going to be several pretty good ways to do something.

If you want to get a better understanding of the patterns that are being implemented by the frameworks and are commonly thrown around in the common vernacular on SO, I would suggest that you read Fowler and GoF. They'll teach all about the basic design patterns you'll use in your development efforts.

Specifically watch for the following:

• Function files that contain LOTS of functions. This is most likely representative of a need to either put functions directly in the scripts that need them or it may also indicate an opportunity to create some more generic functions that can be made to fulfill the roles of a couple of highly specific functions. Of course, if you're building cohesive, well-encapsulated classes you shouldn't run into this problem.
• The do everything class. This is a blob anti-pattern and is really nasty. In this case you need to identify where cohesion and encapsulation are breaking down and use those points as opportunities to break up the class into several smaller, more maintainable classes.
• SQL queries that don't use parameterized queries or at least escaped parameters. Very, very, very bad.
• Any instance where validation is not being performed or is only performed client-side. When developing for the web, the only way to keep your site and your users safe is to assume that everyone else is a black hat.
• A sudden obsessive desire to use a template engine. PHP is a templating language. Make certain that you have clear reasons for adding another layer onto your website before using a template engine.

For further reading please look at the following:

PHP Application Design Patterns
Defend PHP -- useful to give you an idea of the most common criticisms.
Security of strip_tags and mysqlirealescapestring
What should Every PHP Programmer Know
How to Structure an ORM
Best Way to Organize Class Hierarchy
Main Components / Layers of PHP App
Why use Framework for PHP
Recommended Security Training for PHP

Answer 2

• Use a coding standard.
• Use unit testing. PHPUnit and SimpleTest are the major xUnit systems in PHP.
• Be object oriented.
• Use version control. Any version control, just use it.
• If applicable, use a framework. Zend, CodeIgniter, Symfony, and CakePHP are the major ones.
• If no framework, at least use an ORM. Propel and Doctrine are the major ones.
• Document. Heavily. Use PHPdoc or similar.

There are a wealth of tools out there for PHP. Please use them, and write good maintainable code. You'll make everyone happier.