問題描述

我正在嘗試使用 Laravel 創建一個友誼系統(我是從它開始的)，但我被關系阻止了.事情是這樣的:有一張表 Users 和一張表 Friends ，其中包含以下列:

I'm trying to create a Friendship system with Laravel (I'm starting with it) but I'm blocked with relationships. Here's the thing : there is one table Users and one table Friends which contains the following columns :

friends: id, user_id, friend_id, accepted.

它看起來像多對多，所以這是我在用戶類上設置的:

It looks like a Many to Many so here's what I set on User class :

class User extends Eloquent {
    function friends()
    {
        return $this->belongsToMany('User');
    }
}

但是當我嘗試:

$friends = User::find($id)->friends()->get()

我有這個錯誤:

Base table or view not found: 1146 Table 'base.user_user' doesn't exist

我想獲取一個用戶的好友列表，無論用戶是發送邀請還是收到邀請.因此，用戶可以根據 user_id 或friend_id 獲取數據，然后根據該列檢索其他用戶的數據.

I would like to get a list of the Friends of a user, no matters if the user sent the invitation or received it. So the user can ba on user_id or on friend_id and then I retrieve the data of the other user depending of that column.

有什么想法嗎?謝謝！

這是我使用的代碼:

$usersWithFriends = User::with('friendsOfMine', 'friendOf')->get();
$user = User::find(Auth::id())->friends;

foreach($user as $item) {
    echo $item->first()->pivot->accepted;
} 

推薦答案

tldr;您需要 2 個反向關系才能使其工作，請檢查下面的 SETUP 和 USAGE

首先是錯誤 - 這就是你的關系應該是什么樣子:

tldr; you need 2 inverted relationships to make it work, check SETUP and USAGE below

First off the error - this is how your relation should look like:

function friends()
{
  return $this->belongsToMany('User', 'friends', 'user_id', 'friend_id')
    // if you want to rely on accepted field, then add this:
    ->wherePivot('accepted', '=', 1);
}

然后它就會正常工作:

$user->friends; // collection of User models, returns the same as:
$user->friends()->get();

<小時>

設置

但是您希望關系以兩種方式工作.Eloquent 不提供這種關系，因此您可以改為使用 2 個反向關系并合并結果:

SETUP

However you would like the relation to work in both ways. Eloquent doesn't provide a relation of that kind, so you can instead use 2 inverted relationships and merge the results:

// friendship that I started
function friendsOfMine()
{
  return $this->belongsToMany('User', 'friends', 'user_id', 'friend_id')
     ->wherePivot('accepted', '=', 1) // to filter only accepted
     ->withPivot('accepted'); // or to fetch accepted value
}

// friendship that I was invited to 
function friendOf()
{
  return $this->belongsToMany('User', 'friends', 'friend_id', 'user_id')
     ->wherePivot('accepted', '=', 1)
     ->withPivot('accepted');
}

// accessor allowing you call $user->friends
public function getFriendsAttribute()
{
    if ( ! array_key_exists('friends', $this->relations)) $this->loadFriends();

    return $this->getRelation('friends');
}

protected function loadFriends()
{
    if ( ! array_key_exists('friends', $this->relations))
    {
        $friends = $this->mergeFriends();

        $this->setRelation('friends', $friends);
    }
}

protected function mergeFriends()
{
    return $this->friendsOfMine->merge($this->friendOf);
}

用法

通過這樣的設置，您可以做到:

USAGE

With such setup you can do this:

// access all friends
$user->friends; // collection of unique User model instances

// access friends a user invited
$user->friendsOfMine; // collection

// access friends that a user was invited by
$user->friendOf; // collection

// and eager load all friends with 2 queries
$usersWithFriends = User::with('friendsOfMine', 'friendOf')->get();

// then
$users->first()->friends; // collection

// Check the accepted value:
$user->friends->first()->pivot->accepted;

這篇關于與 Laravel 的友誼系統:多對多關系的文章就介紹到這了，希望我們推薦的答案對大家有所幫助，也希望大家多多支持html5模板網！