C# LINQ 顺序错误？

Question

我有一个我想要订购的对象列表，但我不知道如何使用 LINQ 来完成它，也许我在想 LINQ 以不同的方式工作。

我可以通过使用示例中的 where 子句简单地解决问题，但我想了解发生了什么。

谁能解释一下为什么我不能在“值”变量中得到预期的结果？

谢谢

预期结果

[列表“值”中对象的顺序]:

new MyClass{Ordinal = 1, A = true, B = Status.Released, C = 3}
new MyClass{Ordinal = 0, A = true, B = Status.Released, C = 2}
new MyClass{Ordinal = 4, A = true, B = Status.Skipped, C = 5}
new MyClass{Ordinal = 2, A = true, B = Status.Skipped, C = 4}
new MyClass{Ordinal = 3, A = false, B = Status.Skipped, C = 1}

示例

public class Program
{
    static void Main(string[] args)
    {
        var lst = new List<MyClass>{ 
            new MyClass{Ordinal = 0, A = true, B = Status.Released, C = 2},
            new MyClass{Ordinal = 1, A = true, B = Status.Released, C = 3},
            new MyClass{Ordinal = 2, A = true, B = Status.Skipped, C = 4},
            new MyClass{Ordinal = 3, A = false, B = Status.Skipped, C = 1},
            new MyClass{Ordinal = 4, A = true, B = Status.Skipped, C = 5}
        };


        var workaround = lst.Where(i => i.B != Status.Skipped && i.B != Status.Cancelled)
            .OrderByDescending(i => i.A)
            .ThenByDescending(i => i.C)
            .ToList();

        var values = lst.OrderByDescending(i => i.A)
            .ThenBy(i => i.B == Status.Skipped && i.B == Status.Cancelled)
            .ThenByDescending(i => i.C)
            .ToList();

        /* order of the objects in "values"
            new MyClass{Ordinal = 4, A = true, B = Status.Skipped, C = 5}
            new MyClass{Ordinal = 2, A = true, B = Status.Skipped, C = 4}
            new MyClass{Ordinal = 1, A = true, B = Status.Released, C = 3}
            new MyClass{Ordinal = 0, A = true, B = Status.Released, C = 2}
            new MyClass{Ordinal = 3, A = false, B = Status.Skipped, C = 1}
        */
    }
}

public class MyClass
{
    public int Ordinal { get; set; }

    public bool A { get; set; }
    public Status B { get; set; }
    public int C { get; set; }
}

public enum Status
{
    Unknown,
    Released,
    Cancelled,
    Received,
    Processing,
    Succeeded,
    Failed,
    Skipped
}

Answer 1

lambda 表达式

i => i.B == Status.Skipped && i.B == Status.Cancelled

用于 ThenBy 函数将 MyClass 的每个实例映射到 false，假设 Status.Skipped 和 Status.Cancelled 是不同的值；这导致没有有用的排序。也许你的意思是

i => i.B != Status.Skipped && i.B != Status.Cancelled

将状态为 Status.Skipped 和 Status.Cancelled 的条目排到底部。