WordPress.org

Writing Logic Code

The text in the 'Widget logic' field can be full PHP code and should return 'true' when you need the widget to appear. Make good use of WP's own conditional tags.

If there is no 'return' in the text, an implicit 'return' is added to the start and a ';' is added on the end.

Examples:

• is_home() -- main blog/home page
• is_page('about') -- WP 'page' with the given URL slug
• !is_category(array(5,9,10,11)) -- category page of one of the given category IDs
• is_single() && in_category('baked-goods') -- single post that's in the category with this slug
• current_user_can('level_10') -- admin only widget!
• strpos($_SERVER['HTTP_REFERER'], "google.com")!=false -- widget to show when clicked through from a google search
• is_category() && in_array($cat, get_term_children( 5, 'category')) -- category page that's a descendent of category 5
• global $post; return (in_array(77,get_post_ancestors($post))); -- WP page that is a child of page 77
• global $post; return (is_page('home') || ($post->post_parent=="13")); -- home page OR the page that's a child of page 13

Note the extra ';' on the end where there is an explicit 'return'.

Build your own

Try variations on the examples above. Use ! (NOT) in front of a conditional tag to reverse the logic, eg !is_home() to show a widget on any page except the home page.

Use || (OR), && (AND) to make more complex conditions. There are lots of great code examples on the WP forums, and on WP sites across the net. But the WP Codex is also full of good examples to adapt, such as Test if post is in a descendent category.

Remember -- the code runs even if the widget doesn't appear. (Even if it never appears!)

The 'widget_content' filter

Once this option is active (tick the option tickbox at the foot of the widget admin page) you can modify the text displayed by ANY widget from your own theme's functions.php file. Hook into the filter with:

add_filter('widget_content', 'your_filter_function', [priority], 2);

where [priority] is the optional priority parameter for the add_filter function. The filter function can take 2 parameters (hence that final 2) like this:

function your_filter_function($content='', $widget_id='')

The second parameter ($widget_id) can be used to target specific widgets if needed.

Example filters

This adds the widget_id to the foot of every widget:

function reveal_widget_id($content='', $widget_id='')
{   return $content."id=".$widget_id;   }

I was motivated to make this filter in order to render all widget titles with the excellent ttftitles plugin like this:

function ttftext_widget_title($content='', $widget_id='')
{   preg_match("/<h2[^>]*>([^<]+)/",$content, $matches);
    $heading=$matches[1];
    $insert_img=the_ttftext( $heading, false );
    $content=preg_replace("/(<h2[^>]*>)[^<]+/","$1$insert_img",$content,1);
    return $content;
}