Laravel的ORM入门

源码目录在\vendor\laravel\framework\src\Illuminate\Database\Eloquent\Relations下

关系：一对多（One To Many）

场景：每篇博客都有若干条评论，每条评论只属于一篇博客

先定义两个Model，这里为了突出主要矛盾，删除了Model中部分无关代码

namespace App;

use Illuminate\Database\Eloquent\Model;

class Post extends Model
{
        protected $table = 'posts';
        public function Comments()
        {
                return $this->hasMany('App\Comment','PostID','CommentID');
        }
}

以上是博客Post的模型，接下来是评论Comment的模型

namespace App;

use Illuminate\Database\Eloquent\Model;

class Comment extends Model
{
        protected $table = 'comments';
        public function Comment()
        {
                //
        }

        public function Post()
        {
                return $this->belongsTo('App\Post','CommentID','PostID');
        }
}

控制器里：

$articles=Post::where('id','>','50')->where('id','<','52')->get();
foreach($articles as $a){
        //echo $a->id;
        $comments=$a->Comments;
        foreach($comments as $c){
                //echo $c->id;
        }
}