给帖子发表回复后更新帖子回复总数的5种方式

class Comment extends Model
{
    public static function boot()
    {
        parent::boot();

        static::created(function ($comment) {
            // 这里的$comment->topic是假设模型有关联
            // 这里直接+1， 也可以做count
            // 并发会让这种方式不一定精确，有精确需求的请加锁或者考虑其他方式
            // 有删除帖子功能别忘记一样的操作
            $topic = $comment->topic;
            $topic->comment_count++;
            $topic->save();
        });
    }
}Copy

DELIMITER //
CREATE TRIGGER after_comment_insert
AFTER INSERT ON comment
FOR EACH ROW
BEGIN
    UPDATE topic
    SET comment_count = comment_count + 1
    WHERE id = NEW.topic_id;
END; //
DELIMITER ;Copy

// Event: CommentCreated
class CommentCreated
{
    public $comment;

    public function __construct(Comment $comment)
    {
        $this->comment = $comment;
    }
}

// Listener: UpdateTopicCount
class UpdateTopicCount
{
    public function handle(CommentCreated $event)
    {
        // 同方案1一样，想精确得加锁
        $event->comment->topic->comment_count++;
        $event->comment->topic->save();
    }
}Copy

use App\Events\CommentCreated;

static::created(function ($comment) {
    event(new CommentCreated($comment));
});Copy

ALTER TABLE comment
  ADD CONSTRAINT comment_topic_id_fkey
  FOREIGN KEY (topic_id)
  REFERENCES topic(id)
  ON INSERT UPDATE topic.comment_count;Copy

$comment = new Comment();
// ... 填充 $comment 数据并保存
$topic = Topic::find($comment->topic_id);
$topic->comment_count++;
$topic->save();Copy