C# 使用 LINQ 进行多重排序
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Multiple Order By with LINQ
提问by sdanna
I start with a basic class that I want to manipulate in a List using LINQ, something like the following:
我从一个我想使用 LINQ 在 List 中操作的基本类开始，如下所示：
public class FooBar
{
public virtual int Id { get; set; }
public virtual string Foo { get; set; }
public virtual string Bar { get; set; }
}
This is what I ultimately found out to solve my problem using the non lambda LINQ stuff.
这就是我最终发现使用非 lambda LINQ 来解决我的问题的方法。
// code somewhere else that works and gets the desired results
var foobarList = GetFooBarList(); // Abstracted out - returns List<Foobar>
// Interesting piece of code that I want to examine
var resultSet = from foobars in foobarList
orderby foobars.Foo, foobars.Bar
select foobars;
// Iterate and do something interesting
foreach (var foobar in resultSet)
{
// Do some code
}
What I'm really curious about is if the same can be accomplished using the Lambda based extension methods off of generic IEnumerableto accomplish the same thing. Google tells me I can do something like the following to accomplish it:
我真正好奇的是，是否可以使用基于 Lambda 的扩展方法IEnumerable来完成相同的事情。Google 告诉我我可以执行以下操作来完成它：
var resultSet = foobarList.OrderBy(x => new {x.Foo, x.Bar})
.Select(x=>x);
However if I do that I get a runtime error when I hit the foreachstatement. The error tells me that at least one object has to implement IComparible, which I can see that since I'm using an anonymous type for the .OrderBy()method.
但是，如果我这样做，当我点击foreach语句时会出现运行时错误。该错误告诉我至少有一个对象必须实现IComparible，我可以看到这一点，因为我为该.OrderBy()方法使用了匿名类型。
So is there a way to accomplish what I want using the Lambda way?
那么有没有办法使用 Lambda 方式来完成我想要的？
采纳答案by Pop Catalin
You can use the ThenByand ThenByDescendingextension methods:
您可以使用ThenBy和ThenByDescending扩展方法：
foobarList.OrderBy(x => x.Foo).ThenBy( x => x.Bar)
