WordPress 5 Cookbook

Understanding the functionality of the update function

In step 5 of this recipe, we implemented the update function. The update function has two parameters, called $new_instance and $old_instance. Once the options of a widget have been updated, this function will be called with modified values in $new_instance. $old_instance contains the values before the widget options were updated. First, we assign $old_instance to a new variable called $instance. Then, we retrieve the modified values from $new_instance and assign it to $instance with necessary filtering. Finally, we return the modified $instance variable and the data will be saved automatically to the database.

At this stage, the widget's functionality is completed and the widget has been ...