yoren

Yoren Chang

Try it live in your browser — <a href="https://playground.wordpress.net/?blueprint-url=https://raw.githubusercontent.com/1fixdotio/categories-metabox-enhanced/master/blueprint/playground.blueprint.json" rel="nofollow ugc">launch the WordPress Playground demo</a>. Boots a WordPress instance with this plugin active, the Category taxonomy pre-configured as radio buttons, and seeded posts you can edit in the Block Editor or run through Quick Edit / Bulk Edit immediately.
Thanks to <a href="https://github.com/WebDevStudios/Taxonomy_Single_Term" rel="nofollow ugc">Taxonomy_Single_Term</a>, a library created by <a href="http://webdevstudios.com/" rel="nofollow ugc">WebDevStudios</a>, it made my work much easier on creating this plugin.
With Categories Metabox Enhanced, you can:
<ul>
<li>Change the built-in Categories metabox/panel to a single term UI, which means replacing the checkboxes with radio buttons or a select drop-down.</li>
<li>Apply the single term UI to other hierarchical taxonomies from the plugin’s Settings page.</li>
<li>Configure each hierarchical taxonomy independently — the same install can keep one taxonomy as checkboxes while another is forced to radio.</li>
<li>Customize the single term UI by setting these options:
<ul>
<li>Option type (checkbox, radio, or select).</li>
<li>Priority and position (context) of the metabox placement. Classic editor only.</li>
<li>Title of the metabox / Block Editor panel.</li>
<li>Whether child-terms should be indented.</li>
<li>Whether adding new terms from the metabox is enabled.</li>
<li>Whether a term selection is required (Force selection). When on, the classic metabox hides the “None” option, the Block Editor sidebar drops the “— Select —” entry once a term is chosen, and an empty save is substituted with a default term server-side so REST and programmatic callers can’t bypass it.</li>
</ul>
</li>
</ul>
The single-term invariant is enforced everywhere posts can be saved: the Classic Editor metabox, the Block Editor sidebar panel, Quick Edit, Bulk Edit, the REST API, WP-CLI, and any code that calls <code>wp_set_object_terms()</code> directly. The classic-editor and Block Editor surfaces enforce in the UI; everything else is enforced on the server via the <code>set_object_terms</code> action, which coerces multi-term submissions to the last term and substitutes the default term on empty submissions when Force selection is on.
The substituted default term resolves in this order: the <code>default_<taxonomy></code> option (e.g. <code>default_category</code>) → the <code>default_term_<taxonomy></code> option populated by <code>register_taxonomy()</code> <code>default_term</code> arg (WP 5.5+) → the first term ordered by name. Override per taxonomy with the <code>of_cme_force_selection_default_term</code> filter.
The Block Editor sidebar panel is rendered for taxonomies registered with <code>show_in_rest = true</code>. Hierarchical taxonomies that opt out of REST fall back to the Classic Editor metabox path.

Categories Metabox Enhanced

Replace the checkboxes with radio buttons or a select drop-down in the built-in Categories metabox and the Block Editor sidebar panel.

Ben Balter

This plugin will work, “as is”, out of the box, but assumes some level of CSS and developer customization to adapt to your site’s specific needs.
Styles can be overridden via your theme’s style.css
Functionality can be overridden via your theme’s functions.php
”Examples”
Don’t display metabox on “product” post type:
<pre><code>add_filter( 'display_custom_fields', 'bb_no_product_metabox' ); function bb_no_product_metabox( $true, $post ) { if ( $post->post_type == 'product' ) return false; return true; } </code></pre>
Don’t display the product_id metakey
<pre><code>add_filter( 'dcf_postmeta', 'bb_no_product_id' ); function bb_no_product_id( $postmeta ) { unset( $postmeta['product_id'] ); return $postmeta; } </code></pre>
Don’t display metabox title
<pre><code>add_filter( 'dcf_heading', '__return_false' ); </code></pre>
Display metabox below content (rather than floated to the right)
<pre><code>add_filter( 'dcf_before_content', '__return_false' ); </code></pre>

Display Custom Fields

Inserts a Wikipedia-like metabox into posts with all the post's associated custom fields and taxonomy terms.

Categories Metabox Enhanced vs Display Custom Fields