在列表中获取List的不同值 [英] Get distinct values of List in List

问题描述

我正在努力使用db应用程序，我需要在其中获取不同的值.整个结构看起来像这样

I'm struggling with a db application, where I need to get the distinct values. The whole structure looks somewhat like this

class A
{
    public virtual ICollection<B> Bs { get; set; }
}
class B
{
    public virtual C C { get; set; }
}
class C
{
    public int x {get; set;}
}

这是数据库中的模型，我有所有A's的子集.现在，我需要从所有A's中获取所有distinct值C.x. 所以基本上像

This is the model from a db and I have a subset of all A's. Now I need to get all distinct values C.x from all those A's. So basically something like

db.A.Where(something).SelectMany(s => s.Bs.SelectMany(t => t.C.x).ToList().Distinct()).ToList()

但是它告诉我，第二个SelectMany不能从用法中推断出来.

But it tells me, that the second SelectMany cannot be inferred from the usage.

推荐答案

使用以下方法修复代码:

Fix your code like this:

SelectMany(s => s.Bs.Select(t => t.C.x)

请注意，B不是A的成员，而是Bs，第二个SelectMany也应该是Select.

Note that B is not a member of A but Bs, and also your second SelectMany should be Select.

了解更多信息 https://stackoverflow.com/a/25564528/2946329

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