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
About the Author
About the Reviewers
Customer Feedback

Displaying custom post data using filter functions

Once we have captured additional data in the post editor, the next logical step will be to add code to display it when visitors view posts and pages. In the case of our source link data, the most logical place to show this link is after each post's content, which can easily be accomplished by assigning a function to the filter the_content.

This recipe explains how to create a filter function to display the source data associated with a post or page item as a clean link.

Getting ready

You should have already followed the Capturing and displaying information using custom meta boxes recipe to have a starting point for this recipe and the resulting plugin should still be active in your development site. Alternatively, you can get the resulting code (Chapter 5/ch5-post-source-link/ch5-post-source-link-v1.php) from the code bundle you downloaded from the Packt Publishing website ( and rename the file as ch5-post-source...