PHP development article comment system

I recently needed to complete a comment function at work, and I searched online for several display styles of the comment system. Finally, with reference to comment systems such as "Duosuo" and "Changyan", I implemented a simple comment system using PHP language. The implementation process of the two methods (recursive and non-recursive) is recorded, and the advantages and disadvantages of the two methods are analyzed, but how the front-end is implemented is not shown.

First design the database as follows:

create table `comments`(
	`id` bigint unsigned not null AUTO_INCREMENT,
	`arc_id` bigint unsigned not null COMMENT '文章id',
	`user_id` bigint unsigned not null COMMENT '用户id',
	`comment_id` bigint unsigned not null DEFAULT '0' COMMENT '回复某个评论的id',
	`content` varchar(255) not null DEFAULT '' COMMENT '评论或回复的内容',
	`add_time` timestamp not null DEFAULT CURRENT_TIMESTAMP COMMENT '添加时间',
	PRIMARY KEY (`id`),
	KEY `arc_id` (`arc_id`)
)ENGINE=InnoDB DEFAULT CHARSET=utf8 COMMENT '文章评论表';

Create test data as follows:

The specific implementation plan is as follows (in Implemented on the ThinkPHP framework):
1. Recursive method
Advantages: The implementation code is simple, and if the level of comments is fixed at five levels or less, it is recommended to use this method, so that the front-end can easily implement this data result .
Disadvantages: If the level of comments is not fixed, the front end will not be able to display the comment information, and if there are too many levels, it will consume a lot of memory. What’s more terrible is that every recursion has to query the database, and the performance will be reduced. Greatly reduced.

/**
 * @param $arc_id   文章id
 * @param int $comm_id   评论id
 * @param array $result
 * @return array
 */
function getCommlist($arc_id, $comm_id = 0, &$result = array()){   //获取评论列表
	if(empty($arc_id)){
		return array();
	}
	$_where = "arc_id = {$arc_id} AND comment_id = {$comm_id}";
	$res = M('comments')->where($_where)->order('add_time DESC')->select();
	if(empty($res)){
		return array();
	}
	foreach ($res as $cm) {
		$thisArr = &$result[];
		$cm["_child"] = getCommlist($arc_id,$cm['id'],$thisArr);
		$thisArr = $cm;
	}

	return $result;
}

Part of the data is displayed as follows:

#2. Non-recursive method (stack method implementation)
Advantages: only query A primary database has better performance. N-level comments can be realized, and the front-end can also display them well.
Disadvantages: The code is slightly complicated. For fixed-level comments, the front-end display of comments is more complicated.

/**
 * @param $arc_id  文章id
 * @return array
 */
public function getCommlist($arc_id){
	if(empty($arc_id)){
		return array();
	}
	$res = M('comments')->where(array('arc_id'=>$arc_id))->order('add_time ASC')->select();
	$dataList = $stack = array();
	if($res){
		foreach($res AS $k=>$v){   //先将评论的数据进行入库（即comment_id=0）
			if($v['comment_id'] == 0){
				$v['_level'] = 0;   //设置层级数
				$v['_root'] = $v['id'];   //标识评论id
				array_push($stack,$v);   //入栈
				unset($res[$k]);
			}
		}

		while(!empty($stack)){
			$node = array_pop($stack);   //出栈
			$dataList[] = $node;
			foreach($res as $_k=>$_v){
				if($_v['comment_id'] == $node['id']){
					$_v['_level'] = $node['_level']+1;   //设置层级数
					$_v['_root'] = $node['_root'];   //标识评论id
					array_push($stack,$_v);   //入栈
					unset($res[$_k]);
				}
			}
		}
	}

	return $dataList;
}

The data display effect is as follows:

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