Taxonomy Advanced

The taxonomy advanced field allows you to select one or multiple taxonomy terms. This field has several settings that can be displayed as a: simple select dropdown, checkbox list, or beautiful select dropdown with select2 library.

If the taxonomy is hierarchical, you can display the field as a select or checkbox tree, e.g. showing children terms when a parent term is selected.

Taxonomy vs. taxonomy advanced

• Taxonomy field doesn't store data. It just sets post terms. Think about it like a replacement of the Category or Tag meta box of WordPress.
• Taxonomy advanced stores terms' IDs and doesn't set post terms.

Screenshots

The taxonomy field default interface

The taxonomy field with checkbox list interface

The taxonomy field with checkbox tree interface

The taxonomy field with select tree interface

The taxonomy field settings

The taxonomy field with radio list interface

The taxonomy field with radio list inline interface

Settings

Besides the common settings, this field has the following specific settings, the keys are for use with code:

Name	Key	Description
Taxonomies	taxonomy	Taxonomy slug(s). Can be a string (for single taxonomy) or an array (for multiple taxonomies). Required.
Query args	query_args	Query arguments for getting taxonomy terms. Uses same arguments as get_terms(). Optional.
Placeholder	placeholder	The placeholder for the select box. The default is "Select a {taxonomy label}". Applied only when the field type is a select field.
Add new	add_new	Allow users to create a new term when submitting the post (true or false).
Remove default meta box	remove_default	Remove the default WordPress taxonomy meta box. Only works with the classic editor.
Field type	field_type	How the terms are displayed? See below.

This field inherits the look and field (and settings) from other fields, depending on the field type, which accepts the following value:

Field type	Description	Settings inherited from
select	Simple select dropdown.	Select
select_advanced	Beautiful select dropdown using the select2 library. This is the default value.	Select advanced
select_tree	Hierarchical list of select boxes which allows to select multiple items (select/deselect parent item will show/hide child items). Applied only when the taxonomy is hierarchical (like category).	Select
checkbox_list	Flatten list of checkboxes which allows to select multiple items.	Checkbox list
checkbox_tree	Hierarchical list of checkboxes which allows to select multiple items (select/deselect parent item will show/hide child items). Applied only when the taxonomy is hierarchical (like category).	Checkbox list
radio_list	Flatten list of radio boxes which allows to select only 1 item.	Radio

This is a sample field settings array when creating this field with code:

[
    'name'       => 'Taxonomy',
    'id'         => 'taxonomy',
    'type'       => 'taxonomy_advanced',
    'taxonomy'   => 'category',
    'field_type' => 'select_advanced',
],

Ajax load

Meta Box uses ajax to increase the performance of the field query. Instead of fetching all terms at once, the plugin now fetches only some terms when the page is loaded, and then it fetches more terms when users scroll down to the list.

See this video for demonstration (made for posts, but works similar for taxonomies, the UI of the Meta Box Builder was from the old version, the new version of Meta Box Builder has a better UI):

info

This feature is available only for fields that set the field type to select advanced. There are some extra parameters for you to disable or customize.

Enable/Disable ajax requests

This feature is enabled by default when you set the field type to "select advanced".

If you're using code to create this field, the settings to enable/disable it is ajax, which accepts a boolean value (and it's true by default):

[
    'id'       => 'project_cat',
    'title'    => 'Project Categories',
    'type'     => 'taxonomy_advanced',
    'taxonomy' => 'project_cat',
    'ajax'     => true,
],

Setting this parameter to false will disable ajax requests.

Limit the number of terms for pagination

The number of terms for pagination is set via the number parameter in the "Query_args" setting:

[
    'id'         => 'project_cat',
    'title'      => 'Project Categories',
    'type'       => 'taxonomy_advanced',
    'taxonomy'   => 'project_cat',
    'ajax'       => true,
    'query_args' => [
        'number' => 10,
    ],
],

When fetching new terms, the new terms will be appended to the list of options in the dropdown, to make the infinite scroll effect.

Initial load

The number of terms doesn't affect the initial load of the field. When the field is loaded, Meta Box only queries for saved terms (which is usually not many). So the initial query is very minimal and doesn't cause any performance problems.

Searching parameters

You probably don't want to perform an ajax request when opening the dropdown at first. You might want to make ajax requests only when users type something and search for that. To do that, you need to set the minimumInputLength for the input, as below:

[
    'id'         => 'project_cat',
    'title'      => 'Project Categories',
    'type'       => 'taxonomy_advanced',
    'taxonomy'   => 'project_cat',
    'ajax'       => true,
    'query_args' => [
        'number' => 10,
    ],
    'js_options' => [
        'minimumInputLength' => 1,
    ],
],

This parameter sets the minimum number of characters required to start a search. It may be good if you don't want users to make too many ajax requests that could harm your server.

Data

Unlike the taxonomy field, this field saves terms' IDs in the database.

If "Multiple" is not set, a single term ID is saved in the database. Otherwise, the field saves multiple term IDs in a single row in the database in the comma-separated strings (e.g. format 1,2,3).

If the field is cloneable, then the value is stored as a serialized array in a single row in the database.

Template usage

Getting selected term object:

<?php $term = rwmb_meta( 'my_field_id' ); ?>
<pre>
    <!-- Show all data from the selected term -->
    <?php print_r( $term ); ?>
</pre>

Displaying selected term name:

<?php $term = rwmb_meta( 'my_field_id' ); ?>
<p><?= $term->name; ?></p>

or simpler:

<p><?php rwmb_the_value( 'my_field_id', ['link' => false] ) ?></p>

Displaying the selected term with link:

<?php $term = rwmb_meta( 'my_field_id' ); ?>
<p><a href="<?= get_term_link( $term ) ?>"><?= $term->name ?></a></p>

or simpler:

<p><?php rwmb_the_value( 'my_field_id' ) ?></p>

Additional options for rwmb_the_value():

Using rwmb_the_value also has some extra options as following:

<!-- Displaying the term without link -->
<?php rwmb_the_value( 'my_field_id', ['link' => false] ) ?>

<!-- Displaying the term with link to view term (default) -->
<?php rwmb_the_value( 'my_field_id' ) ?>
<?php rwmb_the_value( 'my_field_id', ['link' => 'view'] ) ?>

<!-- Displaying the term with link to edit term -->
<?php rwmb_the_value( 'my_field_id', ['link' => 'edit'] ) ?>

Displaying multiple selected terms:

If "Multiple" is set or the field is cloneable, you can loop through the returned values like this:

<?php $terms = rwmb_meta( 'my_field_id' ); ?>
<h3>Project categories</h3>
<ul>
    <?php foreach ( $terms as $term ) : ?>
        <li><a href="<?= get_term_link( $term ) ?>"><?= $term->name ?></a></li>
    <?php endforeach ?>
</ul>

of simpler:

<h3>Project categories</h3>
<?php rwmb_the_value( 'my_field_id' ); ?>

rwmb_the_value() automatically output multiple selected terms as an unordered list with links to each term.

Filters

rwmb_taxonomy_advanced_choice_label and rwmb_{$field_id}_choice_label

These filters allow developers to change the label of taxonomy_advanced fields. The first label applies to all taxonomy_advanced fields, and the second one is for a specific field.

Example: If you are using a field called my_field and you want to change the label in the select box, use this code:

function my_field_filter( $label, $field, $term ) {
    return $label . ' - Custom text';
}
add_filter( 'rwmb_my_field_choice_label', 'my_field_filter', 10, 3 );