Add a Custom Taxonomy to Vendor Products

Let's add a custom taxonomy to products, for example a "Brand" taxonomy, so that vendors can choose which brand each product belongs to.

Step 1: Create a taxonomy

First of all, we need to create the taxonomy itself if it doesn't already exist.

We can install the CPT UI plugin: https://wordpress.org/plugins/custom-post-type-ui/

Then go to CPT UI -> Add/Edit Taxonomies and create a new taxonomy with these settings:

Then, in Products -> Brands, create a few sample options:

Step 2: Add the taxonomy to the vendor dashboard

Add this PHP code snippet to your site:

add_action('marketking_edit_product_after_tags', function($post){
	if (isset($post->ID)){
		?>
		<div class="row">
			<div class="col-xxl-3 col-md-6 marketking_card_gal_cat_tags">
			    <div class="code-block marketking_cattag_card">
			        <h6 class="overline-title title">
			            <?php esc_html_e('Brands','marketking-multivendor-marketplace-for-woocommerce');?>
			        </h6>
			        <div class="form-group">
			            <div class="form-control-wrap">
			                <?php
			                $selected_brands = wp_get_object_terms($post->ID, 'brand', array('fields' => 'ids', 'hide_empty' => false));
			                $brand_args = array(
			                    'taxonomy' => 'brand',
			                    'name'     => 'marketking_select_brand',
			                    'class'    => 'form-select',
			                    'orderby'  => 'name',
			                    'title_li' => '',
			                    'multiple' => 'multiple',
			                    'hide_empty' => false,
			                    'selected' => implode(',',$selected_brands),
			                );
			                wp_dropdown_categories($brand_args);
			                ?>
			            </div>
			        </div>
			    </div>
			</div>
		</div>
		<?php
	}
}, 10, 1);

// save taxonomy
add_action('marketking_after_save_product', function($product_id, $vendor_id){
    // Save "brand" taxonomy
    $brand_values = isset($_POST['marketking_select_brand']) ? $_POST['marketking_select_brand'] : array();
    foreach ($brand_values as $index => $val){
        $brand_values[$index] = intval($val); // transform to INT
    }
    wp_set_object_terms( $product_id, $brand_values, 'brand' );

}, 10, 2);

This code can be added to the functions.php file of your child theme or to any snippets plugin.

Results

Vendors can now set brands for each product (one or multiple per product):