我收到兩次訊息，重復

我正在開發一個Laravel聊天應用程式，我有一個問題，每條訊息都收到兩次（重復）

這是我的代碼：

return Chat::join('users',  function ($join) {
                $join->on('chats.from_id', '=', 'users.id')
                    ->orOn('chats.to_id', '=', 'users.id');
            })->where(function ($q) {
                $q->where('chats.from_id', Auth::id())->orWhere('chats.to_id', Auth::id());
            })
            ->orderBy('chats.created_at', 'desc')->select('users.id as user_id', 'chats.id as chat_id', 'message')->get();

uj5u.com熱心網友回復：

這是因為您要加入chats并參加users兩次會議。一次from_id又一次，to_id所以它會導致重復的結果。要修復它，您可以通過 php 代碼或 mysql 查詢獲得唯一的行或聯合兩個單獨的查詢。

uj5u.com熱心網友回復：

正如@mohammad-mirsafaei 在他的回答中所說：

這是因為您要加入chats并參加users兩次會議。

1. 要解決此問題：

代替...

->orOn('chats.to_id', '=', 'users.id');

用這個...

->orWhere('chats.to_id', '=', 'users.id');

2. 更完整的答案是：

2a)。將這兩種“關系”方法添加到您的Chat.php模型中。

// ...
    public function from() {
        return $this->belongsTo(User::class, "from_id");
    }
    public function to() {
        return $this->belongsTo(User::class, "to_id");
    }
// ...

2b)。將負責執行查詢的方法添加到Chat.php模型中。

// ...
    public static function chats() {
        return Chat::join('users',  function ($join) {
            $join->on('chats.from_id', '=', 'users.id')
                ->orWhere('chats.to_id', '=', 'users.id');
        })->where(function ($q) {
            $q->where('chats.from_id', Auth::id())->orWhere('chats.to_id', Auth::id());
        })
            ->with(["from" => function($query) {
                return $query->select(["id", "name"]);
            }])
            ->with(["to" => function($query) {
                return $query->select(["id", "name"]);
            }])
            ->orderBy('chats.created_at', 'desc')->select('from_id', 'to_id', 'chats.id as chat_id', 'message')->get();
    }
// ...

樣本輸出：

Ivan@DESKTOP-LQIK691 MINGW64 /c/xampp/htdocs/breezep (master)
$ php artisan tinker
Psy Shell v0.10.6 (PHP 8.0.2 — cli) by Justin Hileman
>>> App\Models\Chat::chats()
=> Illuminate\Database\Eloquent\Collection {#4387
     all: [
       App\Models\Chat {#4381
         from_id: 2,
         to_id: 3,
         chat_id: 5,
         message: "No, I didn't!",
         from: App\Models\User {#4388
           id: 2,
           name: "stevenmwesigwa",
         },
         to: App\Models\User {#4393
           id: 3,
           name: "john ripper",
         },
       },
       App\Models\Chat {#4382
         from_id: 3,
         to_id: 2,
         chat_id: 4,
         message: "The day went well. Did you go to the supermarket today?",
         from: App\Models\User {#4390
           id: 3,
           name: "john ripper",
         },
         to: App\Models\User {#4391
           id: 2,
           name: "stevenmwesigwa",
         },
       },
       App\Models\Chat {#4383
         from_id: 3,
         to_id: 2,
         chat_id: 3,
         message: "I'm fine  how're you?",
         from: App\Models\User {#4390},
         to: App\Models\User {#4391},
       },
       App\Models\Chat {#4384
         from_id: 2,
         to_id: 3,
         chat_id: 2,
         message: "How was your day?",
         from: App\Models\User {#4388},
         to: App\Models\User {#4393},
       },
       App\Models\Chat {#4385
         from_id: 2,
         to_id: 3,
         chat_id: 1,
         message: "Hello Johny",
         from: App\Models\User {#4388},
         to: App\Models\User {#4393},
       },
     ],
   }
>>>

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