If you can write WordPress plug-ins, you can make WordPress do just about anything. From making the site easier to administer, to adding the odd tweak or new feature, to completely changing the way your blog works, plug-ins are the method WordPress offers to customize and extend its functionality. This book will show you how to build all sorts of WordPress plug-ins: admin plug-ins, Widgets, plug-ins that alter your post output, present custom "views" of your blog, and more.

WordPress Plug-in Development (Beginner's Guide) focuses on teaching you all aspects of modern WordPress development. The book uses real and published WordPress plug-ins and follows their creation from the idea to the finishing touches, in a series of carefully picked, easy-to-follow tutorials. You will discover how to use the WordPress API in all typical situations, from displaying output on the site in the beginning to turning WordPress into a CMS in the last chapter. In Chapters 2 to 7 you will develop six concrete plug-ins and conquer all aspects of WordPress development.

Each new chapter and each new plug-in introduces different features of WordPress and how to put them to good use, allowing you to gradually advance your knowledge. This book is written as a guide to take your WordPress skills from the very beginning to the level where you are able to completely understand how WordPress works and how you can use it to your advantage.

What you will learn from this book

• Get to know the WordPress code base, WordPress's plug-in architecture, and the plug-in application programming interface (API) and learn how to hack it
• Master the WordPress database and the API - access and manipulate data, handle user roles and permissions, posts, and so on
• Hook into the rest of WordPress using actions and filters
• Change the way your WordPress backend looks by customizing menus, submenus, and the plug-in admin panel
• Integrate AJAX and jQuery into your plug-ins to dynamically generate content
• Hook directly to WordPress edit pages and use AJAX to generate fast searches
• Integrate your plug-in with WordPress panels and the tinyMCE editor
• Access and work with third-party APIs like Flickr
• Implement localization support for users of other languages
• Maintain and manage your plug-in using SVN and publish it to the WordPress Plugin Repository
• Handle security issues and make your plug-ins safer to use

We cover the development of six plug-ins from start to finish:

• Digg-this: Adds a Digg This button to each post.
• Live Blogroll: Adds a recent posts popup for each blog in your blogroll.
• The Wall widget: Displays comments on the sidebar without reloading the page.
• Snazzy Archives: Presents your site archives in a unique visual way.
• Insights: Access your articles and Flickr images from within the WordPress edit page.
• Post Types: Provides pre-defined post templates to quickly add a photo or a link to your blog.

This is a Packt Beginners Guide, which means it focuses on practical examples and has a fast-paced but friendly approach, with the opportunity to learn by experiment and play. Each chapter builds a practical plug-in from the ground up using step-by-step instructions. Individual sections show you how to code some functionality into your plug-in and follow up with a discussion of concepts.

Who this book is written for

This book is for programmers working with WordPress, who want to develop custom plug-ins and to hack the code base. You need to be familiar with the basics of WordPress and PHP programming and believe that code is poetry, this book will handle the rest.