C# - 错误 CS1928 : Checking for list element with derived class

Question

我有像这样从库 (Satsuma) 派生的自定义类:

public class DCBaseNode : Node {
    public bool selected = false;
}

和一个Neighbors库中返回 List<Node> 的方法.我希望能够做到这一点:

graph.Neighbors(theNode).Any(n => n.selected == true);

但是Any看到 n作为Node , 不是 DCBaseNode , 所以它不明白 .selected .

所以我尝试了:

graph.Neighbors(theNode).Any<DCBaseNode>(n => n.selected == true);

...这给了我这个错误:

Error CS1928: Type System.Collections.Generic.List<Satsuma.Node>' does not contain a memberAny' and the best extension method overload `System.Linq.Enumerable.Any(this System.Collections.Generic.IEnumerable, System.Func)' has some invalid arguments

...但我不清楚参数为何无效。

Answer 1

听起来你需要沮丧...

graph.Neighbors(theNode)
    .OfType<DCBaseNode>()
    .Any(n => n.selected);