2023年5月21日 08:14:45go评论75阅读模式

英文:

Is there a way to extract list from list without making it a List<List<>> situation?

问题

从列表的列表中提取列表...

我有一个结构如下：

Struct1
{
    public int blah-blah
    public string blah-blah-blah
    public List<Struct2> problematicList
}

var problem = List<Struct1>

我想从Struct1的列表中提取所有Struct2的元素。查询如下：

List<Struct2> struct2s = 
                problem.Select(x => x.problematicList.Struct2).ToList();

这给了我一个列表的列表，我无法正确理解如何使用单一的LINQ查询来完成。一定有一种方法，不是吗？

英文:

Extract list from list of lists...

I have a structure like

Struct1
{
 public int blah-blah
 public string blah-blah-blah
 public List&lt;Struct2&gt; problematicList
}

var problem = List&lt;Struct1&gt;

And I want to exctract all of Struct2's elements from a List of Struct1
Query like

List&lt;Struct2&gt; struct2s= 
                problem.Select(x =&gt; x.problematicList.Struct2).ToList();

gives me a list of lists, and I can't wrap my head around of how to do it corretly with a singular linq query. There must be a way, is it not?

答案1

得分: 2

你寻找的是 SelectMany。

使用 SelectMany，你可以编写类似以下的代码：

List<Struct2> struct2s = problem.SelectMany(x => x.problematicList).ToList();

英文:

What you're looking for is SelectMany.

Using SelectMany, you would write something like the following:

List&lt;Struct2&gt; struct2s = problem.SelectMany(x =&gt; x.problematicList).ToList();

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