Miscellaneous Developer Updates in 5.2

New wp_body_open Theme Hook

5.2 will introduce a new wp_body_open() function that is used to trigger a wp_body_open action. This action is intended to allow developers to inject code immediately following the opening <body> tag.

Themes are encouraged to begin using this hook as soon as 5.2 is released. The function should be placed just inside the opening <body> tag of the template file. For example:

<body <?php body_class(); ?>>
<?php wp_body_open(); ?>

Usage of this hook should be reserved for output of unseen elements like <script> tags or additional metadata. It should not be used to add arbitrary HTML content to a page that could break layouts or lead to unexpected situations.

Backward Compatibility

In order to support previous versions of WordPress, it is recommended you use a shim in your theme to prevent fatal errors from the undefined function.

<?php
if ( ! function_exists( 'wp_body_open' ) ) {
    function wp_body_open() {
        do_action( 'wp_body_open' );
    }
}

Note that if your theme is going to be submitted to the theme repository, then you won’t be able to use the wp_ prefix, as it will get flagged by the Theme Check. An alternative is to call do_action directly where the wp_body_open() function is placed in the first example, like this:

<body <?php body_class(); ?>>
<?php 
if ( function_exists( 'wp_body_open' ) ) {
    wp_body_open();
} else {
    do_action( 'wp_body_open' );
}

Plugins can detect the use of this function in a theme by calling did_action( 'wp_body_open' ) and falling back to alternative methods if the action has not fired.

See #12563 and #46679 for more information.

Login Header Adjustments

The <h1> on wp-login.php previously used the title attribute inconsistently between multisite and single site. In multisite, the value of this attribute was the title of the network, but on a single site, it merely duplicated the link text. As part of #24766, many of the title attributes throughout core have been removed, as they are often redundant or useless.

In WordPress 5.2, this title attribute has been removed and its associated filter, login_headertitle, has been deprecated. If the deprecated filter is used, it now applies to the link text. A new login_headertext filter has been added in its place.

In addition to the <h1> changes, the link on the WordPress logo now always points to WordPress.org by default. In prior versions, it would point to the primary site of the network on multisite. This URL can still be filtered using login_headerurl.

See: #42537

Editor Image Caption Styles

In the block editor, the font-size and color attributes were removed from the figcaption element unless the active theme has opted into default block styles.

Additionally, a margin: 0; attribute applied to .block-editor-rich-text__editable was removed from the RichText component, so as to allow theme styles to control those margins without high specificity. If your plugin relied on this margin, you’ll need to add this back to the necessary elements.

See: wordpress/gutenberg/pull/14366

Walker_Category HTML Attributes

A new category_list_link_attributes filter has been added to Walker_Category to allow customization of the HTML attributes applied to a category list item’s anchor element.

This complements the page_menu_link_attributes filter in Walker_Page and the nav_menu_link_attributes filter in Walker_Nav_Menu.

See #40666

New Additional Content Filter on User Delete Action

When users are deleted from a site, WordPress checks to confirm that they do not have posts or links assigned to them. However, there are cases where a plugin may have content associated with them outside of a post_author or link_owner relationship.

WordPress 5.2 introduces a new users_have_additional_content filter, which allows plugins to run additional checks for custom content relationships.

Note: This filter specifically doesn’t override the system users_have_content checks to avoid any undesired suppression of the reassign functionality. Instead it enables the ability to flag that a user has additional content.

Developers should note that this filter doesn’t conduct the reassignment operations on the data, this will be done by the delete_user or deleted_user actions which provide the ID of the user as well as the ID of the user for reassignment if selected.

Using the Filter

Below is a simple example of how a plugin could use the filter along with the delete_user action to allow the re-assignment of non-standard content.

First the filter returns true to signify that users have additional content. This triggers the content reassignment UI to appear in the admin for all users being deleted.

It then uses the delete_user action hook to reassign additional content at the same time as any standard core content.

function myplugin_users_have_additional_content( $has_content, $user_ids ) {
	if ( ! $has_content ) {
		// Check if any of the the users being deleted have additional content
		if ( myplugin_check_users_have_content( $user_ids ) ) {
			return true;
		}
	}
	return $has_content;
}
add_filter( ‘users_have_additional_content’, ‘myplugin_users_have_additional_content’, 10, 2 );

function myplugin_reassign_user_content( $deleted_user, $reassigned_user ) {
	if ( $reassigned_user ) {
		// Re-assign the content from the deleted user
		myplugin_reassign_coauthor( $deleted_user, $reassigned_user );
	}
}
add_action( ‘delete_user’, ‘myplugin_reassign_user_content’, 10, 2 );

See: #36860

Other Updates of Note:

  • As part of the 2019 focus of improving automatic updates, the sodium_compat library will now be included in WordPress. Sodium Compat is a polyfill for the Sodium cryptography library for PHP versions <7.2. Including this will facilitate security enhancements, with the initial focus of enabling more secure signing and verification of update packages. See: #45806
  • Twemoji is now updated to version 12.0.1. See: #46805
  • Fixed a bug where an Allow header was not being returned for OPTIONS requests to the REST API. See: #45753
  • A $domain parameter has been added to translate_user_role(). This will allow translations of custom user roles added in plugins. See: #38736

#5-2, #dev-notes, #editor, #themes