Laravel 多对多自引用表只能以一种方式工作 [英] Laravel Many to many self referencing table only works one way

问题描述

我已经建立了关系和模型如下:

I have set up the relationship and the models as below:

数据透视表架构

Schema::create('friend_user', function(Blueprint $table) {
    $table->increments('id');
    $table->integer('user_id')->unsigned();
    $table->integer('friend_id')->unsigned();
    $table->timestamps();
});

数据透视表播种器(这定义了用户1"所属的两个友谊"，一个是在 user_id 中指定了用户 1，另一个是在朋友 ID 中列出了用户 1):

pivot table seeder (this defines two 'friendships' to which user '1' belongs one where user 1 is specified in the user_id and the second where user 1 is listed in the friend id):

    $friend_user = array(
        array(
            'id' => 1,
            'user_id' => 1,
            'friend_id' => 3,
        ),
        array(
            'id' => 2,
            'user_id' => 4,
            'friend_id' => 1,
        ),

    );

用户模型

public function friends()
{
 return $this->belongsToMany('User', 'friend_user', 'user_id', 'friend_id');
}

这是 Taylor Otwell 在这里建议的:https://github.com/laravel/framework/issues/441

This is as suggested by Taylor Otwell here: https://github.com/laravel/framework/issues/441

这一切都有效，但是当我运行以下命令时，我只得到一个结果:

This all works but when I run the following command I get only one result:

foreach(Auth::user()->friends as $i) {
    var_dump($i->id);
}

这将返回值 '3' 但不是预期的 4.我理解为什么会发生这种情况(因为 user_id 不是friend_id)但是我怎样才能让它返回属于一个用户的所有朋友(即所有朋友)的集合，而不管连接的哪一端(user_id 或friend_id)用户是?

This returns the value '3' but not 4 as expected. I understand why this is happening (as the user_id is not the friend_id) but how can I get this to return a collection of all friends belonging to a user (ie all friendships) regardless of which end of the connection (user_id or friend_id) the user is?

推荐答案

使用新函数代替创建两条记录.

Instead of creating two records use a new function.

public function friends()
{
  return $this->belongsToMany('User', 'friend_user', 'user_id', 'friend_id');
}

// Same table, self referencing, but change the key order
public function theFriends()
{
  return $this->belongsToMany('User', 'friend_user', 'friend_id', 'user_id');
}

//You can then call opposite record(s) using:
foreach( Auth::user()->theFriends as $theFriends )

我在我的项目中使用了这种方法，因此我可以更好地分离组织结果.

I used this approach in my project so I can have better separation for organizing the results.

这篇关于Laravel 多对多自引用表只能以一种方式工作的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！