问为产品标签添加产品过滤器

EN

function modify_query($query) {
  if( ! is_admin() && $query->is_main_query() && $query->query_vars['post_type'] == 'product') {

    if( isset( $_GET['tag_product'] ) ) {

      $query->set( 'tax_query', array (
        array(
          'taxonomy' => 'product_tag',
          'field'    => 'term_id',
          'terms'    => absint( $_GET['tag_product'] ),
        )
      ));

    }
  }
}

add_action( 'pre_get_posts', 'modify_query' );

<label><?php _e('Tags'); ?></label>
<form action="<?php bloginfo('url'); ?>/" method="get">
    <div>
        <?php
        $args = array(
            'taxonomy' => 'product_tag', // Taxonomy to return. Valid values are 'category', 'post_tag' or any registered taxonomy.
            'show_option_none' => 'Select tag',
            'show_count' => 1,
            'orderby' => 'name',
            'value_field' => 'slug',
            'echo' => 0,
            'name' => 'tag_product'
        );
        $select = wp_dropdown_categories( $args );
        $select = preg_replace("#<select([^>]*)>#", "<select$1 onchange='return this.form.submit()'>", $select);
        echo $select;
        ?>
        <noscript><div><input type="submit" value="Filter" /></div></noscript>
    </div>
</form>