Laravel - Table::find($is) 的奇怪行为,它是 returns 行数组,而不是 1 行

Laravel - Strange behaviour of Table::find($id), it returns array of rows, instead of 1 row

我怎么理解Table::find($id)应该等同于Table::where('id',$id)->first(), 但我收到数组而不是 1 条记录..

Order.php(型号):

public function change_user($order_id, $user_id) {
    $order = Order::find($order_id);
    dd($order);
    if ($order == null) return false;
    $order->user = $user_id;
    return $order->save();
} 

和 dd 的结果:

Collection {#270 ▼
  #items: array:1 [▼
    0 => Order {#271 ▼
      +timestamps: true
      #guarded: array:1 [▶]
      #hidden: array:2 [▶]
      #connection: null
      #table: null
      #primaryKey: "id"
      #perPage: 15
      +incrementing: true
      #attributes: array:30 [▶]
      #original: array:30 [▶]
      #relations: []
      #visible: []
      #appends: []
      #fillable: []
      #dates: []
      #dateFormat: null
      #casts: []
      #touches: []
      #observables: []
      #with: []
      #morphClass: null
      +exists: true
      +wasRecentlyCreated: false
    }
  ]
}

如果我错误地认为 find 应该 return 1 行,我仍然对此有疑问,因为当我删除 dd() 时收到错误消息:

BadMethodCallException in Macroable.php line 81: Method save does not exist.

    in Macroable.php line 81
    at Collection->__call('save', array()) in Order.php line 64
    at Collection->save() in Order.php line 64
    at Order->change_user(array('57'), '18') in RegistersUsers.php line 69
    at AuthController->register(object(Request), object(Order))
    at call_user_func_array(array(object(AuthController), 'register'), array(object(Request), object(Order))) in Controller.php line 76

您是否更改了主键?

检查 $id 是否不是数组。如果是数组,Laravel returns多1行。

如果您将数组传递给 find,它会 return 一个集合。

好像$order_id是一个数组