I have solved the problem myself, but it is not a pretty one.
With the function attached to the add_meta_boxes
action hook, I change the callback function that builds the category box. It replaces this function with the customized function post_categories_meta_box_custom
.
post_categories_meta_box_custom
is a copy of post_categories_meta_box
from wp-admin/includes/meta-boxes.php
. With the help of simple-html-dom the <li>...</li>
with the specified id is removed.
<?php
function terms_meta_boxes($post_type, $post) {
global $wp_meta_boxes;
foreach ($wp_meta_boxes[$post_type] as $context => $priorities) {
foreach ($priorities as $priority => $ids) {
foreach ($ids as $id => $meta_box) {
$tax = get_taxonomy( $meta_box['args']['taxonomy'] );
if ( $tax->hierarchical ) {
$wp_meta_boxes[$post_type][$context][$priority][$id]['callback'] = 'post_categories_meta_box_custom';
}
}
}
}
}
add_action('add_meta_boxes', 'terms_meta_boxes', 10, 2);
/**
* Custom function to display post categories form fields.
* Original wp function: post_categories_meta_box.
*
* @param object $post
*/
function post_categories_meta_box_custom( $post, $box ) {
$defaults = array('taxonomy' => 'category');
if ( !isset($box['args']) || !is_array($box['args']) )
$args = array();
else
$args = $box['args'];
extract( wp_parse_args($args, $defaults), EXTR_SKIP );
$tax = get_taxonomy($taxonomy);
?>
<div id="taxonomy-<?php echo $taxonomy; ?>" class="categorydiv">
<ul id="<?php echo $taxonomy; ?>-tabs" class="category-tabs">
<li class="tabs"><a href="#<?php echo $taxonomy; ?>-all" tabindex="3"><?php echo $tax->labels->all_items; ?></a></li>
<li class="hide-if-no-js"><a href="#<?php echo $taxonomy; ?>-pop" tabindex="3"><?php _e( 'Most Used' ); ?></a></li>
</ul>
<div id="<?php echo $taxonomy; ?>-pop" class="tabs-panel" style="display: none;">
<ul id="<?php echo $taxonomy; ?>checklist-pop" class="categorychecklist form-no-clear" >
<?php $popular_ids = wp_popular_terms_checklist($taxonomy); ?>
</ul>
</div>
<div id="<?php echo $taxonomy; ?>-all" class="tabs-panel">
<?php
$name = ( $taxonomy == 'category' ) ? 'post_category' : 'tax_input[' . $taxonomy . ']';
echo "<input type="hidden" name="{$name}[]" value="0" />"; // Allows for an empty term set to be sent. 0 is an invalid Term ID and will be ignored by empty() checks.
?>
<ul id="<?php echo $taxonomy; ?>checklist" class="list:<?php echo $taxonomy?> categorychecklist form-no-clear">
<?php
ob_start();
wp_terms_checklist($post->ID, array( 'taxonomy' => $taxonomy, 'popular_cats' => $popular_ids ) );
$html_checklist = str_get_html(ob_get_clean());
$disabled_cats = get_option('disabled_cats', array());
foreach ($disabled_cats[$taxonomy] as $cat) {
$html_checklist->find('li#category-' . $cat, 0)->outertext="";
}
echo $html_checklist->save();
?>
</ul>
</div>
<?php if ( current_user_can($tax->cap->edit_terms) ) : ?>
<div id="<?php echo $taxonomy; ?>-adder" class="wp-hidden-children">
<h4>
<a id="<?php echo $taxonomy; ?>-add-toggle" href="#<?php echo $taxonomy; ?>-add" class="hide-if-no-js" tabindex="3">
<?php
/* translators: %s: add new taxonomy label */
printf( __( '+ %s' ), $tax->labels->add_new_item );
?>
</a>
</h4>
<p id="<?php echo $taxonomy; ?>-add" class="category-add wp-hidden-child">
<label class="screen-reader-text" for="new<?php echo $taxonomy; ?>"><?php echo $tax->labels->add_new_item; ?></label>
<input type="text" name="new<?php echo $taxonomy; ?>" id="new<?php echo $taxonomy; ?>" class="form-required form-input-tip" value="<?php echo esc_attr( $tax->labels->new_item_name ); ?>" tabindex="3" aria-required="true"/>
<label class="screen-reader-text" for="new<?php echo $taxonomy; ?>_parent">
<?php echo $tax->labels->parent_item_colon; ?>
</label>
<?php wp_dropdown_categories( array( 'taxonomy' => $taxonomy, 'hide_empty' => 0, 'name' => 'new'.$taxonomy.'_parent', 'orderby' => 'name', 'hierarchical' => 1, 'show_option_none' => '— ' . $tax->labels->parent_item . ' —', 'tab_index' => 3 ) ); ?>
<input type="button" id="<?php echo $taxonomy; ?>-add-submit" class="add:<?php echo $taxonomy ?>checklist:<?php echo $taxonomy ?>-add button category-add-sumbit" value="<?php echo esc_attr( $tax->labels->add_new_item ); ?>" tabindex="3" />
<?php wp_nonce_field( 'add-'.$taxonomy, '_ajax_nonce-add-'.$taxonomy, false ); ?>
<span id="<?php echo $taxonomy; ?>-ajax-response"></span>
</p>
</div>
<?php endif; ?>
</div>
<?php
}
?>