Question

我有3张桌子。

Car  - Door - Fan

汽车可以有一个或多个门。一扇门可以有一个或多个风扇。

结构

Car - id |名称

门 - id | car_id |侧

粉丝 - id | door_id |颜色

我的模型已定义：

汽车

   public class Car extends Eloquent{

    protected $table = "car";

     public function door()
    {
        $this->hasMany('Room');
    }

    }

门

   public class Door extends Eloquent{

    protected $table = "door";

   public function car()
    {
        $this->belongsTo('Car');
    }

   public function fan()
    {
        $this->hasMany('Fan');
     }

   }

范

      public class Fan extends Eloquent{

      protected $table = "fan";
      public function door(){
        $this->belongsTo('Door');
      } 
    }

我可以找回与汽车相关的门，但不能检索与门相关的风扇

这很好用，但是当我尝试检索门的扇子时，它会抛出一个错误

  $car = Car::find(1);
  foreach($car->door as $dr)
   {
     echo $dr->side;
   }

-

     Relationship method must return an object of type Illuminate\Database\Eloquent\Relations\Relation         
   $car  = Car::find(1);
   foreach($car->door as $dr)
   {
      echo $dr->size;
       foreach($dr->fan as $fn)
       {
          echo $color;
       }
   }

Answer 1

您需要为所有关系添加return，例如

public class Car extends Eloquent{

protected $table = "car";

    public function doors() // doors with 's' because many
    {
        return $this->hasMany('Door'); // Door for class not door
    }

}

并使用eager loading来缓解N + 1查询

Answer 2

Fan模型中的这一行

$this->belongsTo('door');

需要父模型的精确拼写，因此它应该是

$this->belongsTo('Door');

首都为'D'。

laravel关系一对多表

2 个答案: