至少一个对象必须在 linq 查询中实现 IComparable 错误

Question

var pairs = new [] { new { id = 1, name = "ram", dept = "IT", sal = "3000" }, new { id = 2, name = "ramesh", dept = "IT", sal = "5000" }, new { id = 3, name = "rahesh", dept = "NONIT", sal = "2000" },
                             new { id = 5, name = "rash", dept = "NONIT", sal = "7000" } };
        var query = from stud in pairs
                    where (stud.name.StartsWith("r") && stud.id % 2 != 0)
                    //orderby stud.sal descending
                    group stud by stud.dept into grps
                    select new { Values = grps, Key = grps.Key, maxsal=grps.Max() };
                    ////select new { id = stud.id };

        foreach (dynamic result in query)
        {
            Console.WriteLine(result.Key);
            Console.WriteLine(result.maxsal);
            foreach (dynamic result2 in result.Values)
            {
                Console.WriteLine(result2.id + "," + result2.sal);
            }


        }
        Console.Read();

我收到错误“至少一个对象必须实现 IComparable。”，谁能解释我为什么会收到此错误？

Answer 1

您正在调用grps.Max() 以获取组中的最大项目。您的匿名对象不可比较。 Linq 将如何知道哪一个是最大的？它应该使用id 属性进行比较，还是使用name？

我相信你想选择最高薪水：

maxsal = grps.Max(s => Int32.Parse(s.sal))