Question

我想从LineOfBusiness promotionCatalogResponseRootObject等于PromotionID

的myId来审核

public class PromotionCatalogResponseRootObject
{
   public PromotionCatalogResponse PromotionCatalog { get; set; }
}

public class Promotion
{
  public string PromotionId { get; set; }
  public string LineOfBusiness { get; set; }
  public string PromotionName { get; set; }
}

public class PromotionCatalogResponse
{
  public List<Promotion> Promotion { get; set; }
}

属性

string myId = "7596";
string lineOfBusiness = dataPromotionCatalog.PromotionCatalog
                                            .Promotion.Find(p => p.LineOfBusiness);

我开始这样，但我知道我做错了。请指导

select max(access_type) , owner from access group by owner

Answer 1

您遗漏的是Find方法期望接收带有bool返回值的谓词，但您返回的是string LineOfBusiness属性。

首先过滤所需的项目，然后选择所需的属性。另外，我使用的是Where而不是Find。（Find() vs. Where().FirstOrDefault()）

var result = dataPromotionCatalog.PromotionCatalog.Promotion
                                 .Where(i => i.PromotionId == myId)
                                 .Select(i => i.LineOfBusiness);

或查询语法

var result = (from item in dataPromotionCatalog.PromotionCatalog.Promotion
              where item.PromotionId == myId
              select item.LineOfBusiness);

如果您希望/想要拥有一个项目，请使用FirstOrDefault：

var result = dataPromotionCatalog.PromotionCatalog.Promotion
                 .FirstOrDefault(i => i.PromotionId == myId)?.LineOfBusiness;

用于查找属性的Lambda表达式

1 个答案: