我目前使用以下表格：

<form role="search" method="get" class="search-form" action="<?php echo home_url( \'/\' ); ?>">

        <input type="search" class="search-field" placeholder="<?php echo esc_attr_x( \'Type Business or Town\', \'placeholder\' ) ?>" value="<?php echo get_search_query() ?>" name="s" title="<?php echo esc_attr_x( \'Search for:\', \'label\' ) ?>" />

        <input type="text" value="<?php echo get_query_var(\'location\'); ?>" name="location" id="location" class="headersearch location" placeholder="<?php esc_attr_e( \'Enter your county..\', \'search-cust\' ); ?>" />

        <input type="hidden" name="post_type" value="business" />
        <input type="submit" class="button radius tiny success" style="width: 100%;" value="<?php esc_attr_e( \'Search...\', \'search-cust\' ); ?>" />
</form>

我在函数中也有这个。php：

    function custom_cpt_search( $query ) {
       if ( is_search() && $query->is_main_query() && $query->get( \'s\' ) ){
            $query->set(\'post_type\', array(\'business\'));
        }
        return $query;
    };
add_filter(\'pre_get_posts\', \'custom_cpt_search\');

理想情况下，我希望将第二个输入作为下拉式分类法列表，而不是输入中的类型，理想情况下，列出分类法中的所有类别，而不是仅列出其中包含帖子的类别。第一个下拉项是占位符，例如“选择您的县”。

编辑以使其更清楚，并删除我已解决的部分问题。

<form role="search" method="get" class="search-form" action="<?php echo home_url( \'/\' ); ?>">

        <input type="search" class="search-field" placeholder="<?php echo esc_attr_x( \'Search Business or Service\', \'placeholder\' ) ?>" value="<?php echo get_query_var(\'business\'); ?>" name="s" title="<?php echo esc_attr_x( \'Search for:\', \'label\' ) ?>" />

            <?php $location_args = array(\'taxonomy\' => \'location\', \'value_field\' => \'slug\', \'name\' => \'location\', \'show_option_none\' => __( \'Select County\' ),\'option_none_value\' => \'0\', \'order\' => \'ASC\', \'hide_empty\' => 0); ?> 
            <?php wp_dropdown_categories($location_args); ?>

   <input type="hidden" name="post_type" value="business" />
    <input type="submit" class="button" style="width: 100%;" value="<?php esc_attr_e( \'Search...\', \'custom\' ); ?>" />

</form>

<select name="yourselect"><option value="1">Value 1</option>

...

</select>

if( !empty( $_GET[\'yourselect\'] ) ) {
    $query->set(\'tax_query\', array(
        array(
            \'taxonomy\' => \'YOUR_TAXONOMY_NAME\',
            \'field\' => \'id\', // or slug if you want
            \'terms\' => $_POST[\'yourselect\']
        )
    );
}