Jump to the code if you’re not interested in the backstory.
I recently had to investigate how to customize the “meta” widget provided by WordPress.
I maintain the Wikimedia Blog, and we wanted to include a link to our posting guidelines to the “meta” section of our sidebar.
There is no straightforward way to do this; the widget can’t be edited from within the admin area.
One possibility was to replace the standard meta widget by a custom text widget, with the same content and links, and to add our guidelines to the mix. But this meant losing the nice context-aware links (e.g. “Register” vs. “Site admin”, and “Log in” vs. “Log out”, respectively for logged-out and logged-in users) provided by built-in WordPress functions (wp_register and wp_loginout): widget text can’t embed PHP code.
Another possibility was to install a third-party plugin to customize the meta widget (or allow PHP code in widget text). I’m usually reluctant to using plugins for simple changes like the one we wanted to do. Both our Operations staff and I prefer to keep the amount of third-party plugins installed on the blog to a minimum, for various reasons (security, maintenance, maintainability, etc.)
Because there are no hooks to plug into the widget’s behavior, most of the solutions I’ve seen online consist either of using a third-party plugin, or messing with WordPress core files, which is a no-go for me.
The third possibility, which is the one I went for, was to create our own meta widget. This is what the code below does.
Result: Our blog guidelines inserted into the meta widget.
I used the WordPress widgets API to create a widget, as well as the content of the standard meta widget, located in wp-includes/default-widgets.php. The code is located in our WMBlog plugin, a set of customizations specific to our blog that work independently of the theme.
The custom widget replicates the functionality of the standard meta widget (with the handy context-aware links) and also includes the link to our guidelines. It was a bit more work, but it’s cleaner and more robust that way. Once the widget is available, an admin can replace the standard widget with the custom one.
If you want to add stuff to the meta widget, or remove some of its standard content, this is probably the Right™ Way to do it. You’ll want to look at lines 42 to 51 in the code below.
Note: The code hasn’t been deployed to production yet; it’ll appear on the Wikimedia blog in a few days.
Code
/* =========================================================
Replicate the default meta widget and extend it to include
a link to the Wikimedia blog guidelines */
class WMBlog_meta_widget extends WP_Widget {
function WMBlog_meta_widget() {
// (constructor) Instantiate the parent object
parent::WP_Widget( /* Base ID */'WMBlog_meta_widget', /* Name */'WMBlog_meta_widget', array( 'description' => 'The default meta widget plus Wikimedia-specific stuff' ) );
}
function form( $instance ) {
// output the options form on admin
// i.e. for now only the widget's title
if ( $instance ) {
$title = esc_attr( $instance[ 'title' ] );
}
else {
$title = __( 'New title', 'text_domain' );
}
?>
<p>
<label for="<?php echo $this->get_field_id('title'); ?>"><?php _e('Title:'); ?></label>
<input class="widefat" id="<?php echo $this->get_field_id('title'); ?>" name="<?php echo $this->get_field_name('title'); ?>" type="text" value="<?php echo $title; ?>" />
</p>
<?php
}
function update( $new_instance, $old_instance ) {
// process widget options to be saved
$instance = $old_instance;
$instance['title'] = strip_tags($new_instance['title']);
return $instance;
}
function widget( $args, $instance ) {
// output the content of the widget
extract( $args );
$title = apply_filters( 'widget_title', $instance['title'] );
echo $before_widget;
if ( !empty( $title ) ) { echo $before_title . $title . $after_title; } ?>
<ul>
<?php wp_register(); ?>
<li><?php wp_loginout(); ?></li>
// Link to our own posting guidelines
<li><a href="//meta.wikimedia.org/wiki/Wikimedia_Blog/Guidelines" title="General contribution guidelines for the Wikimedia blog">Blog guidelines</a></li>
<li><a href="<?php bloginfo('rss2_url'); ?>" title="<?php echo esc_attr(__('Syndicate this site using RSS 2.0')); ?>"><?php _e('Entries <abbr title="Really Simple Syndication">RSS</abbr>'); ?></a></li>
<li><a href="<?php bloginfo('comments_rss2_url'); ?>" title="<?php echo esc_attr(__('The latest comments to all posts in RSS')); ?>"><?php _e('Comments <abbr title="Really Simple Syndication">RSS</abbr>'); ?></a></li>
<li><a href="http://wordpress.org/" title="<?php echo esc_attr(__('Powered by WordPress, state-of-the-art semantic personal publishing platform.')); ?>">WordPress.org</a></li>
<?php wp_meta(); ?>
</ul>
<?php echo $after_widget;
}
}
function WMBlog_register_widgets() {
// register the plugin's available widgets
register_widget( 'WMBlog_meta_widget' );
}
// plug in the widgets registration
add_action( 'widgets_init', 'WMBlog_register_widgets' );
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