Laravel许多自我参考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

我已经建立了以下关系和模型：

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();
});

透视表播种器（这定义了用户'1'所属的两个友谊，用户1在user_id中指定，第二个用户1在朋友ID中列出）：

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在这里所建议的： 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);
}

这将按预期的方式返回值3，而不返回4。我明白为什么会发生这种情况（因为user_id不是friend_id），但是如何让这个返回一个属于一个用户的所有朋友的集合（即所有的友谊），无论连接的哪一端（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

而不是创建两个记录使用新功能。

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，所以我可以有更好的分离来组织结果。

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

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