LInq Order By和Order By Desc

Question

我使用"Linq"来过滤对象列表并对它们进行排序,比如

myList.Where(x => x.Item!= "SF" && x.AdSize == minadSize)
      .OrderBy(x => x.ManufacturingDate)
      .OrderBy(x=>x.ExpiryDate);

我怀疑我是否做得对,如果我想在多个字段上"排序"那么是否有必要使用多个Order By子句,不能用单个"OrderBy"来完成

Answer 1

不要使用多个OrderBy电话 - 使用OrderBy后跟ThenBy:

var query = myList.Where(x => x.Item!= "SF" && x.AdSize == minadSize)
                  .OrderBy(x => x.ManufacturingDate)
                  .ThenBy(x => x.ExpiryDate); // Could add more ThenBy calls

如果您使用OrderBy两次,它将按到期日期对已按日期排序的列表重新排序,而我假设您只想按生产日期等于具有相同生产日期的项目的到期日期订购,这就是上述操作.

显然也有一种ThenByDescending方法.例如:

var query = people.OrderBy(x => x.LastName)
                  .ThenBy(x => x.FirstName)
                  .ThenByDescending(x => x.Age)
                  .ThenBy(x => x.SocialSecurity);