向Wordpress搜索添加自定义输入字段

我的目标是在Wordpress搜索表单中添加两个输入字段，名字和姓氏。每一个都将显示来自帖子类型"服务"的尊重的自定义元字段的帖子结果。但出于某种原因，当我测试它时，它没有显示任何具有自定义元字段的帖子。

这是迄今为止我在searchform.php文件中的代码。

<?php 
$meta_query = array();
if( !empty( $_GET['first_name'] ) ) {
    $meta_query[] = array( 'key' => 'first_name', 'value' => $_GET['first_name'] );
}
if( !empty( $_GET['last_name'] ) ) {
    $meta_query[] = array( 'key' => 'last_name', 'value' => $_GET['last_name'] );
}
$search = new WP_Query( array(
    'post_type' => 'service',
    'meta_query' => $meta_query
) );
?>
<form role="search" method="get" id="searchform" action="<?php echo home_url( '/' ); ?>">
<input type="text" name="s" id="s" <?php if(is_search()) { ?>value="<?php the_search_query(); ?>" <?php } else { ?>value="Enter keywords &hellip;" onfocus="if(this.value==this.defaultValue)this.value='';" onblur="if(this.value=='')this.value=this.defaultValue;"<?php } ?> /><br />
<label>First Name</label><input type="text" name="first_name" />
<br />
<label>Last Name</label><input type="text" name="last_name"/>
<input type="submit" id="searchsubmit" value="Search" />
</form>

以下是我的search.php文件中的所有代码：

<?php
/**
 * @package WordPress
 * @subpackage Law Business
 * @since Law Business 1.0
 * 
 * Search Page Template
 * Created by CMSMasters
 * 
 */
if( $_GET['first_name'] ) {
    $meta_query[] = array( 'key' => 'first_name', 'value' => $_GET['first_name'] );
}
if( $_GET['last_name']  ) {
    $meta_query['relation'] = 'OR';
    $meta_query[] = array( 'key' => 'last_name', 'value' => $_GET['last_name'] );
}
get_header();

$cmsms_option = cmsms_get_global_options();

$cmsms_layout = $cmsms_option[CMSMS_SHORTNAME . '_search_layout'];
if (!$cmsms_layout) { 
    $cmsms_layout = 'r_sidebar'; 
}

echo '<!--_________________________ Start Content _________________________ -->' . "'n";
if ($cmsms_layout == 'r_sidebar') {
    echo '<section id="content" role="main">' . "'n't";
} elseif ($cmsms_layout == 'l_sidebar') {
    echo '<section id="content" class="fr" role="main">' . "'n't";
} else {
    echo '<section id="middle_content" role="main">' . "'n't";
}
?>
    <div class="entry-summary">
        <section class="blog">
<?php 
if (!have_posts()) : 
    echo '<div class="error_block">' . 
        '<h2>' . __('Nothing found. Try another search?', 'cmsmasters') . '</h2>';
    get_search_form();
    echo '</div>';
else : 
    while (have_posts()) : the_post();
        if (get_post_type() == 'post') {
            if (get_post_format() != '') {
                $cmsms_service_format = get_post_meta(get_the_ID(), 'cmsms_service_format', true);
            } 
        } elseif (get_post_type() == 'service') {
            $cmsms_service_format = get_post_meta(get_the_ID(), 'cmsms_service_format', true);
            if (!$cmsms_service_format) { 
                $cmsms_service_format = 'slider'; 
            }
?>
            <article id="post-<?php the_ID(); ?>" <?php post_class('format-' . $cmsms_service_format); ?>>
                <?php 
                    cmsms_heading(get_the_ID(), 'service');
                    if (has_post_thumbnail()) {
                        cmsms_thumb(get_the_ID(), 'post-thumbnail', true, false, true, false, true, true, false);
                    }
                    the_excerpt();
                    cmsms_more(get_the_ID(), 'service');
                ?>
            </article>
            <div class="divider"></div>
<?php 
        } elseif (get_post_type() == 'page') { 
?>
            <article id="post-<?php the_ID(); ?>" <?php post_class('format-page'); ?>>
                <?php 
                    cmsms_heading(get_the_ID());
                    if (has_post_thumbnail()) {
                        cmsms_thumb(get_the_ID(), 'post-thumbnail', true, false, true, false, true, true, false);
                    }
                    the_excerpt();
                ?>
                    <div class="entry-content">
                        <h6><?php _e('This page contains your query', 'cmsmasters'); ?></h6>
                    </div>
                    <footer class="entry-meta">
                    <?php cmsms_more(get_the_ID()); ?>
                    </footer>
            </article>
            <div class="divider"></div>
<?php 
        }
    endwhile;
    pagination();
endif; 
?>
        </section>
    </div>
</section>
<!-- _________________________ Finish Content _________________________ -->
<?php
if ($cmsms_layout == 'r_sidebar') {
    echo "'n" . '<!-- _________________________ Start Sidebar _________________________ -->' . "'n" . 
    '<section id="sidebar" role="complementary">' . "'n";
    get_sidebar();
    echo "'n" . '</section>' . "'n" . 
    '<!-- _________________________ Finish Sidebar _________________________ -->' . "'n";
} elseif ($cmsms_layout == 'l_sidebar') {
    echo "'n" . '<!-- _________________________ Start Sidebar _________________________ -->' . "'n" . 
    '<section id="sidebar" class="fl" role="complementary">' . "'n";
    get_sidebar();
    echo "'n" . '</section>' . "'n" . 
    '<!-- _________________________ Finish Sidebar _________________________ -->' . "'n";
}
get_footer();

如果有任何帮助，我将不胜感激。