Book Image

WordPress Plugin Development Cookbook - Second Edition

By : Yannick Lefebvre
Book Image

WordPress Plugin Development Cookbook - Second Edition

By: Yannick Lefebvre

Overview of this book

WordPress is a popular, powerful, and open Content Management System. Learning how to extend its capabilities allows you to unleash its full potential, whether you're an administrator trying to find the right extension, a developer with a great idea to enhance the platform for the community, or a website developer working to fulfill a client's needs. This book shows readers how to navigate WordPress' vast set of API functions to create high-quality plugins with easy-to-configure administration interfaces. With new recipes and materials updated for the latest versions of WordPress 4.x, this second edition teaches you how to create plugins of varying complexity ranging from a few lines of code to complex extensions that provide intricate new capabilities. You'll start by using the basic mechanisms provided in WordPress to create plugins and execute custom user code. You will then see how to design administration panels, enhance the post editor with custom fields, store custom data, and modify site behavior based on the value of custom fields. You'll safely incorporate dynamic elements on web pages using scripting languages, and build new widgets that users will be able to add to WordPress sidebars and widget areas. By the end of this book, you will be able to create WordPress plugins to perform any task you can imagine.
Table of Contents (20 chapters)
Title Page
Credits
About the Author
About the Reviewers
www.PacktPub.com
Customer Feedback
Dedication
Preface

Troubleshooting coding errors and printing variable content


As you transcribe code segments from the pages of this book or start writing your own plugins, there is a strong chance that you will have to troubleshoot problems with your code or have trouble working with data that your plugin is meant to manipulate. This recipe shows the basic techniques to identify and quickly resolve these errors while creating a plugin that will hide an item from the navigation menu for users who are not logged in to your site.

How to do it...

  1. Navigate to the WordPress plugin directory of your development installation.
  2. Create a new directory called ch2-nav-menu-filter.
  3. Navigate to this directory and create a new text file called ch2-nav-menu-filter.php.
  4. Open the new file in a code editor and add an appropriate header at the top of the plugin file, naming the plugin Chapter 2 - Nav Menu Filter.

 

  1. Add the following line of code to register a function that will be called when WordPress is preparing data to display...