Laravel 5.3查询，用于从4个通过外键进行连接的表中获取结果

// 在User模型中定义与其他表的关联
class User extends Model
{
    public function posts()
    {
        return $this->hasMany(Post::class);
    }
}

// 在Post模型中定义与其他表的关联
class Post extends Model
{
    public function user()
    {
        return $this->belongsTo(User::class);
    }

    public function comments()
    {
        return $this->hasMany(Comment::class);
    }

    public function likes()
    {
        return $this->hasMany(Like::class);
    }
}

// 在Comment模型中定义与其他表的关联
class Comment extends Model
{
    public function post()
    {
        return $this->belongsTo(Post::class);
    }
}

// 在Like模型中定义与其他表的关联
class Like extends Model
{
    public function post()
    {
        return $this->belongsTo(Post::class);
    }
}

// 执行查询操作
$users = User::with('posts.comments.likes')->get();

foreach ($users as $user) {
    foreach ($user->posts as $post) {
        foreach ($post->comments as $comment) {
            // 处理评论
        }

        foreach ($post->likes as $like) {
            // 处理点赞
        }
    }
}