LINQ的自定义排序 [英] Custom sorting with LINQ

问题描述

我似乎失去了一些东西微不足道。

It seems that i'm missing something trivial.

总之，这里有云：

var order = new[]{1,3,2};
var foos = new[]{new Foo{Id=1}, new Foo{Id=2}, new Foo{Id=3}};

如何使用LINQ按订单阵列FOOS排序？

How to sort foos by order array using Linq?

期望的结果：

foos == new[]{new Foo{Id=1}, new Foo{Id=3}, new Foo{Id=2}};

编辑：

命令包含富IDS 。抱歉，我没有提到。有时候问的问题比正确回答却更难。 ：）

Order contains Foo ids. Sorry that i didn't mention that. Sometimes it's even harder to ask question properly than to answer it. :)

推荐答案

好吧，这个问题似乎并没有要的完全的我清楚，所以我会尽力澄清我的认为的你问：

Okay, the question doesn't seem to be entirely clear to me, so I'll try to clarify what I think you're asking:

• 您有ID序列，所需顺序


• 您有对象的集合，的不按正确的顺序的，而是用相应的ID


• 你想获得对象的集合在同一顺序的ID序列

• You have a sequence of IDs, in the desired order
• You have a collection of objects, not in the right order, but with corresponding IDs
• You want to get the collection of objects in the same order as the ID sequence

正确？

这将是：

var orderedFoos = from orderedId in order
                  join foo in foos on orderedId equals foo.Id into groups
                  select groups.Single();

您需要一个加入到... 验证您没有任何丢失或 FOOS 重复的ID。它不会，但是，检测，如果你已经在订单有遗漏或重复的ID。如果你知道，一切都将是正确的（即会有顺序 FOOS 只有一个条目每个条目和反之亦然），那么一个简单的连接是好的：

You need a join ... into to verify that you don't have any missing or duplicate IDs in foos. It won't, however, detect if you've got missing or duplicate IDs in order. If you know that everything will be correct (i.e. there will be exactly one entry in foos for every entry in order and vice versa) then a simple join is okay:

var orderedFoos = from orderedId in order
                  join foo in foos on orderedId equals foo.Id
                  select foo;

可以在点标记表示为：

which can be expressed in dot notation as:

var orderedFoos = order.Join(foos, order => order, foo => foo.ID, (o, f) => f);

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