The first step in creating a custom widget is to define its name and indicate which class contains all of its implementation functions. 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 sidebars.
This recipe defines a new widget that displays recent book reviews from the custom post type category created in Chapter 4, The Power of Custom Post Types.
You should have already followed the Updating page title to include custom post data using plugin filters recipe from Chapter 4, The Power of Custom Post Types, to have a starting point for this recipe. Alternatively, you can get the resulting code (
Chapter 4/ch4-book-reviews/ch4-book-reviews-v11.php) from the code bundle and activate the
Chapter 4 - Book Reviews plugin.