Creating a new widget in WordPress
The first step in creating a custom widget is to define its name and indicate the class that contains all of its implementation functions. We also need to specify a function to render the widget's contents. Once the new element has been registered with the system, it will immediately appear in the widget list, where users will be able to drag and drop it to their widget areas.
You should have already followed the Updating the page title to include custom post data using plugin filters recipe in Chapter 4, The Power of Custom Post Types, to have a starting point for this recipe. Alternatively, you can get the resulting code (
/ch4-book-reviews/ch4-book-reviews-v12.php) from the book's GitHub page and make sure that the Chapter 4 - Book Reviews plugin is activated.
How to do it...
Follow these steps to define a new widget that displays recent book reviews from the custom post type created in Chapter 4, The Power...