plugin-development - Read For Learn

How to add a new plugin page under desired Options page?

Use add_submenu_page instead. <?php add_submenu_page( $parent_slug, $page_title, $menu_title, $capability, $menu_slug, $function ); ?> $parent_slug should be one of the following For Dashboard: add_submenu_page( ‘index.php’, … ); Also see add_dashboard_page() For Posts: add_submenu_page( ‘edit.php’, … ); Also see Also see add_posts_page() For Media: add_submenu_page( ‘upload.php’, … ); Also see add_media_page() For Links: add_submenu_page( ‘link-manager.php’, … ); … Read more

Turn Shortcode Gallery into Carousel in WordPress 4.4

You can piggyback off of the WP Gallery shortcode to render your slider. This example is adapted from the Owl Carousel Demo / Docs. To use it, create a WP Gallery and add the attribute owl=”true”. Obviously there are better ways to enqueue scripts but this can guide you on gallery modifications. NOTE: It’s best … Read more

add_filter OO with parameters

It’s done the same way you would do in procedural, you need to provide the priority and the number of parameters so you would have; add_filter(‘wp_get_attachment_image_src’, array($this, ‘useCDN’), 10, 3); to pass 3 additional parameters to the filter

Notice: _usort_terms_by_ID is deprecated since version 4.7.0! Use wp_list_sort instead

The function wp_list_sort() has been introduced in WordPress 4.7. It wasn’t available before. That’s probably why your plugin isn’t using it. The function _usort_terms_by_ID() is still working, and it is actually much faster than wp_list_sort(). Which makes it hard to understand why it has been deprecated. But in your own code keep in mind that … Read more

Enqueue script only when shortcode is used, with WP Plugin Boilerplate

Why it’s not working: You need to use the wp_enqueue_scripts action hook. You’ve used wp_register_script as an action hook, however, there is no action hook named wp_register_script in WordPress core. If this was just a silly mistake, then you already have the answer. Read on if you need more information regarding the topic: Attaching a … Read more

Check for featured image in WP_Query

Technically featured image is custom field with name _thumbnail_id that holds attachment ID. So you can easily query with something like: $args = array( ‘meta_query’ => array( array( ‘key’ => ‘_thumbnail_id’, ) ) ); $query = new WP_Query( $args ); Size on other hand is attribute of that attachment and not post itself. You will … Read more

jQuery in header or footer

There is a lot of leftovers in script-related articles in Codex that are not entirely correct (putting it mildly). The enqueue should not be done before wp_head(), it should be done on wp_enqueue_scripts. Which is technically early inside wp_head(). It doesn’t harm performance, because registering/enqueueing script is merely explaining to WordPress how it should be … Read more

How to tell if an option has been created vs an empty option?

Options that don’t exist get the fact of their non-existence cached in memory when you attempt to get them. So you can check that cache to determine the difference. $value = get_option(‘example’); $notoptions = wp_cache_get( ‘notoptions’, ‘options’ ); if ( isset( $notoptions[‘example’] ) ) { // option does not exist } else { // option … Read more

Contact Form 7: wp_mail doesn’t work after update to 4.6

The solution has been found here – Make WordPress Core I’ve made changes in wp-includes/pluggable.php on line 352 from $phpmailer->setFrom( $from_email, $from_name ); to $phpmailer->setFrom( $from_email, $from_name, false ); And it works! Thanks to Marius L. J. (Clorith)!

How to Get a List of Sub Blogs without Using get_blog_list()?

Trac has some discussion and code for possible replacement in future version, ticket #14511 new function – wp_get_sites($args).

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