LINQ：在子列表中创建条件 Where 子句

Question

I need help to build a "query" using LINQ `where". I'm not getting this alone.

I need to create a conditional clause, but into a child list.

By the way, here is an example.

public void Main{
    List<Father> Fathers = getFathers(); 

    //How can I create this clause? 
    Fathers.Where(x=>x.age > 50 && x.ChildrenGirl.Where(y=>y.ID == 5))

}

public class Father{
    public int ID { get; set; }
    public int age {get; set;}
    public List<ChildGirl> ChildrenGirl  { get; set; }
    public List<ChildBoy> ChildrenBoy { get; set; }
}

public class ChildGirl{
    public int ID { get; set; }
    public int power {get;set;}
}

public class ChildBoy{
    public int ID { get; set; }
    public int power {get;set;}
}

Answer 1

您可以使用Any函数来检查是否至少存在一个条件

   Fathers.Where(x => x.age > 50 && x.ChildrenGirl.Any(y => y.ID == 5));

Answer 2

First make all your properties public. Nothing will work without that.

You may find using the query comprehension syntax is easier for queries like this. This is the query you are looking for, using that syntax:

 var result = from father in GetFathers()
     from girl in father.ChildrenGirl
     where father.age > 50 && girl.ID == 5
     select father;

When you are updating your question, you should provide an implementation of GetFathers() that fills up a collection of Father objects, each with some children. I'd have tested my code a lot more if you had done that.