New WP_Widget Class In WordPress 2.8

In WordPress 2.8, there is a new WP_Widget class, which personally I like it very much as now the multi-instances of widgets is handled by WordPress, all you need to do is just to extends the WP_Widget class and overwrite 3 of the functions namely widgets(), update() and form();

Below is a sample code taken from my WP-Polls that displays Polls Widget. It is tested and it works perfectly. Hope it is useful for plugin authors.

 __('Put a poll that you have added in WP-Polls on your sidebar', 'wp-polls'));
		$this->WP_Widget('polls', __('Polls'), $widget_ops);
	}

	// Display Widget
	function widget($args, $instance) {
		extract($args);
		$title = esc_attr($instance['title']);
		$poll_id = intval($instance['poll_id']);
		$display_pollarchive = intval($instance['display_pollarchive']);
		echo $before_widget.$before_title.$title.$after_title;
		get_poll($poll_id);
		if($display_pollarchive) {
			display_polls_archive_link();
		}
		echo $after_widget;
	}

	// When Widget Control Form Is Posted
	function update($new_instance, $old_instance) {
		if (!isset($new_instance['submit'])) {
			return false;
		}
		$instance = $old_instance;
		$instance['title'] = strip_tags($new_instance['title']);
		$instance['poll_id'] = intval($new_instance['poll_id']);
		$instance['display_pollarchive'] = intval($new_instance['display_pollarchive']);
		return $instance;
	}

	// DIsplay Widget Control Form
	function form($instance) {
		global $wpdb;
		$instance = wp_parse_args((array) $instance, array('title' => __('Polls', 'wp-polls'), 'poll_id' => 0, 'display_pollarchive' => 1));
		$title = esc_attr($instance['title']);
		$poll_id = intval($instance['poll_id']);
		$display_pollarchive = intval($instance['display_pollarchive']);
?>

25 thoughts on “New WP_Widget Class In WordPress 2.8”

Brian Meagher 17th March 2009 at 18:30

Lester, can you explain what the new WP_widget class means to us non-developers?
What can the end user expect to see when this class gets implemented?

Lester Chan Post author17th March 2009 at 21:31

For non-developers using WP, you can except multi-instances of all widgets even those plugin that has widgets provided that the plugin author has updated the code.

Taking WP-Polls as an example, you can have 10 Polls Widget now instead of the usual 1.

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Fitline 24th March 2009 at 18:34

Thanks for the really helpful info. That’s a 5 stars for sure.

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Harsh Agrawal 18th May 2009 at 03:58

Just saw this update on Twitter and seems like wordpress is keeping up its promise by giving the best of feature with every new release.

Oyun Hileleri 24th May 2009 at 01:26

Thank you. This worked perfectly. =]

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Leon 8th June 2009 at 02:43

Hi
Thanks for your guide. I have followed your guide and managed to create multiple instances of the plug-in and had then displayed them on different sidebars.
But when I try to change the options on one widget on a sidebar … the changes will automatically apply to all the instances of widgets on all other sidebars!?
Do you have an idea on how to allow the plug-in handle multiple instances of widgets? Or …
Anyway, I have learnt a lot for the first time about Widget once read this guide. Thanks again
Leon

Lester Chan Post author8th June 2009 at 08:53

Could you try on my wp-polls2.50 on WP2.8 Beta/RC1, http://downloads.wordpress.org/plugin/wp-polls.zip and see if the same happens as well?

Romain 15th June 2009 at 20:12

You should change `$title = attr($instance['title']);` into `$title = esc_attr($instance['title']);` on line 13.

This issue could confuse some plugin developer.

Lester Chan Post author16th June 2009 at 12:10

Thanks updated. This post is posted before the esc_* function takes place.

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Randy 14th July 2009 at 03:31

Lester,

I’ve zipped the file and uploaded it using the 2.8.1 plugin page on my site. It says it uploaded successfully but I’m getting the error ‘plugin does not have a valid header’ when I try to activate it. Do you know what this is?

Lester Chan Post author14th July 2009 at 09:08

Erm this is not a full plugin code, it is just a snippet

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Jodi 5th August 2009 at 07:57

Lester — thank you!! I have been all over the Internet and tried many tutorials for adding a WP2.8 widget to my plugin and nothing worked until I found your post. Thank you for sharing your code. It has helped me tremendously!

Lester Chan Post author5th August 2009 at 11:58

No problem Jodi! Glad it has help you =)

mewebhost 14th August 2009 at 18:39

Lester, thanks! This was just what I was looking for.

Ahmed 30th August 2009 at 06:56

LC, I am impressed. Speechless for this tutorial, I’ve been able to convert to this method and it saves time and code and gives us developers and blog users great flexibility. Thanks! Searched the whole Google but didnt find something close to this tutorial. Its straightforward and simple.

Lester Chan Post author31st August 2009 at 04:49

Thanks for the kind compliments =)

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