在LINQ中重构查询

Question

我有一个查询需要通过循环遍历主对象的值来检查对象列表中的值。怎么可以在下面重新编码？

foreach (var kd in dto.KeyDriverModels)
{
  var keyDriverModelNodeValue = result.SingleOrDefault(x => x.KeyDriverModelId == kd.ID);
  kd.SelectionStatus = keyDriverModelNodeValue != null ? 
                         keyDriverModelNodeValue.SelectionStatus : string.Empty;
}

Answer 1

我尝试为您的代码建模并将代码重写为Linq。看看是否有效

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        static DTO dto = new DTO();
        static void Main(string[] args)
        {
            List<KeyDriver> keyDrivers = new List<KeyDriver>();
            List<KeyDriver> result = keyDrivers.Where(x => x.KeyDriverModelId > 1000).ToList();

            foreach (var kd in dto.KeyDriverModels)
            {
                var keyDriverModelNodeValue = result.SingleOrDefault(x => x.KeyDriverModelId == kd.ID);
                kd.SelectionStatus = keyDriverModelNodeValue != null ?
                                       keyDriverModelNodeValue.SelectionStatus : string.Empty;
            }

            //new code
            var kd1 = from r in result
                      join d in dto.KeyDriverModels
                      on r.KeyDriverModelId equals d.ID  into drs
                      from dr in drs
                      select new { dr }.dr.SelectionStatus != null ? dr.SelectionStatus : string.Empty;
        }
    }
    public class DTO
    {
        public List<KeyDriverModel> KeyDriverModels { get; set; }
    }
    public class KeyDriverModel
    {
        public int ID { get; set; }
        public string SelectionStatus { get; set; }
    }
    public class KeyDriver
    {
        public int KeyDriverModelId { get; set; }
        public string SelectionStatus { get; set; }

    }
​

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