LIKE support for meta keys in 5.1

WordPress 5.1 introduces limited LIKEsupport for metaMeta Meta is a term that refers to the inside workings of a group. For us, this is the team that works on internal WordPress sites like WordCamp Central and Make WordPress. keys when using WP_Meta_Query. The new compare_key parameter (meta_compare_key as a top-level WP_Query query arg) accepts a value of LIKE in addition to the default =. See #42409 and [42768]. Here’s an example of how the new parameter is used:

$q = new WP_Query(
  array(
    'post_type'  => 'my_custom_post_type',
    'meta_query' => array(
      array(
        'compare_key' => 'LIKE',
        'key'         => 'foo',
      ),
    ),
  )
);

This will generate a query of the form ... AND meta_key LIKE '%foo%' ....

This enhancementenhancement Enhancements are simple improvements to WordPress, such as the addition of a hook, a new feature, or an improvement to an existing feature. follows from changes in WordPress 4.8.3 to the way that MySQLMySQL MySQL is a relational database management system. A database is a structured collection of data where content, configuration and other options are stored. https://www.mysql.com wildcard characters are handled when building queries. The changes in 4.8.3 broke compatibility for some plugins that passed wildcards into the key parameter of meta queries. The new compare_keyfeature in WP 5.1 is not a full replacement for the previous behavior, but it should allow for most use cases. See #43445 for discussion.

#5-1, #dev-notes, #query