Custom Taxonomies for Blocks

Custom taxonomies that were developed prior to the release of WordPress 5.0 (the Gutenberg release) may not be compatible with the WordPress block editor.

Custom taxonomies require that the “show_in_rest” property be set to “true” in order to work with the block editor. “show_in_rest” was added with WordPress 4.7 and the integration of the WordPress JSON REST API. Sites using custom taxonomies that were created prior to this likely do not have this property set. Additionally, the default value for “show_in_rest” is “false” (this is poorly documented), ergo older custom taxonomies will not appear in the WordPress block editor interface.

This plugin will take any custom taxonomy where the “show_in_rest” feature is set to “false” and change it to “true”. It will not add any additional REST properties, such as “rest_base” or “rest_controller_class”. If you need those properties set for any reason, you will need to update your custom taxonomy where it is being registered.