WordPress文章增加“历史上的今天”功能

来自柳城博主的一个“历史上的今天”的功能，开发成自己的独立代码版本就是如下代码，添加到主题函数文件即可。

function wp_today(){
	global $wpdb;
	$post_year = get_the_time('Y');
	$post_month = get_the_time('m');
	$post_day = get_the_time('j');
	$sql = "select ID, year(post_date_gmt) as h_year, post_title, comment_count FROM 
			$wpdb->posts WHERE post_password = '' AND post_type = 'post' AND post_status = 'publish'
			AND year(post_date_gmt)!='$post_year' AND month(post_date_gmt)='$post_month' AND day(post_date_gmt)='$post_day'
			order by post_date_gmt DESC limit 5";
	$histtory_post = $wpdb->get_results($sql);
	if( $histtory_post ){
		foreach( $histtory_post as $post ){
			$h_year = $post->h_year;
			$h_post_title = $post->post_title;
			$h_permalink = get_permalink( $post->ID );
			$h_comments = $post->comment_count;
			$h_post .= "<li><strong>$h_year:</strong>&nbsp;&nbsp;<a href='".$h_permalink."' title='".$h_post_title."' target='_blank'>$h_post_title($h_comments)</a></li>";
		}
	}
	if ( $h_post ){
		$result = "<h2>历史上的今天:</h2><ul>".$h_post."</ul>";
	}
	return $result;
}

在文章模板调用函数即可。

<?php echo wp_today(); ?>

以上是手动添加代码到调用位置，想要自动添加到文章底部，在上面的funtions.php函数中继续添加以下代码。

function wp_today_auto($content){
    if( is_single() ){
        $content = $content.wp_today();
    }
    return $content;
}
add_filter('the_content', 'wp_today_auto',9999);

实现功能。