Laravel pluck 指定字段为数组key

     /**
      * 获取erp 里的单位
      * @return mixed
      */
     protected function get_units(){
          $key = 'erp:units';
          if(Cache::has($key)){
               return Cache::get($key);
          }
          else
          {
               $units = ErpUnit::all()->pluck(null,'name')->toArray();
               if($units){
                    Cache::forever($key, $units);
               }
               return $units;
          }
     }

效果：

    array:6 [▼    
      "g" => array:11 [▼
        "id" => 1
        "pid" => 0
        "type" => "weight"
        "name" => "g"
        "name_cn" => "克"
        "rate" => "1.000000"
        "user_id" => 1
        "deleted_at" => null
        "created_at" => null
        "updated_at" => null
        "rank" => 0
      ]
      "ml" => array:11 [▶]
      "ton" => array:11 [▶]
      "kg" => array:11 [▶]
      "mg" => array:11 [▶]
      "l" => array:11 [▶]
    ]