如何针对同一张表急切加载多个 belongsTo 关系？

Question

使用以下模型，用户与汽车有 2x 关系。两者都指向同一张表，但使用不同的字段（daily_car_id +weekend_car_id）：

class User extends Model
    public function dailyCar() {
        return $this->belongsTo(Car::class, 'daily_car_id', 'id');
    }
    public function weekendCar() {
        return $this->belongsTo(Car::class, 'weekend_car_id', 'id');
    }
}

除了急切加载之外，这一切都完美无缺：

User::with(['dailyCar', 'weekendCar'])->findOrFail($id);

预期

# 10 is the weekend car id and 12 is the daily
SELECT * FROM `car` WHERE `car`.`id` in (10, 12)

实际结果（不正确意外）

# 10 is the weekend car id and 12 is the daily
SELECT * FROM `car` WHERE `car`.`id` in (10)
SELECT * FROM `car` WHERE `car`.`id` in (12)

当对同一个表使用多个 belongsTo 关系时，有没有办法预先加载？

Answer 1

您可以将您的急切负载更改为：

$user = User::find($id);
$car = Car::where('id', $user->dailyCar->id)->where('id', $user->weekendCar->id)->get();