Question

我有3种类型的对象，TypeA，TypeB，TypeC。 TypeA有一个TypeB列表，TypeB有一个TypeC列表，TypeC有一些我想跟踪的变量

Class TypeA
{
  List<TypeB> MyListOfTypeB;
  //...
}

Class TypeB
{
  List<TypeC> MyListOfTypeC;
  //...
}

Class TypeC
{
  int SomeInteger;
  //...
}

给定List<TypeA> MyListOfTypeA，我想寻找满足特定条件的所有TypeC对象，例如，SomeInteger＆gt; 100.除了为/ foreach循环嵌套之外，Linq的方法是什么？

Answer 1

这就是你想要的东西我想：

var result = MyListOfTypeA.SelectMany(b => b.MyListOfTypeB.SelectMany(c => c.MyListOfTypeC.Select(x => x.SomeInteger > 100))).ToList();

Answer 2

var MyListOfTypeA = new List<TypeA>();
// ...
var cItems = 
    from a in MyListOfTypeA
    from b in a.MyListOfTypeB
    from c in a.MyListOfTypeC
    where c.SomeInteger > 100
    select c;

以上相当于调用SelectMany LINQ函数，但在我看来它更清晰，更容易阅读。

使用LINQ函数（正如Dmitry已经建议的那样，但经过一些修改）：

var cItems = 
    MyListOfTypeA.SelectMany( a => a.MyListOfTypeB )
                 .SelectMany( b => b.MyListOfTypeC )
                 .Where( c => c.SomeValue > 200 );

Answer 3

您可以使用Linq以下方式执行此操作：

    var myListOfTypeA = new List<TypeA>();

    // fill your list here

    var typeCs = from typeA in myListOfTypeA
                 from typeB in typeA.MyListOfTypeB
                 from typeC in typeB.MyListOfTypeC
                 where typeC.SomeInteger > 100
                 select typeC;

Answer 4

您需要浏览所有子列表，from可以为您做什么。

var ta = new TypeA();

var allTypeCsThatSatisfyMyCondition = 
    from tb in ta.MyListOfTypeB                     // This will iterate to each item in the list
    from tc in tb.MyListOfTypeC                     // This will iterate to each item in the *sublist*
    where tc.SomeInteger > 100          // Condition could be anything; filter the results
    select tc;                                      // When you select, you tell your iterator to yield return that value to the caller.

return allTypeCsThatSatisfyMyCondition.ToList();    // To list will force the LINQ to execute and iterate over all items in the lists, and add then to a list, effectively converting the returned items to a list.

Linq：有没有办法搜索符合条件的值的对象列表列表？

4 个答案: