使用lambda从对象及其列表创建通用列表

Question

I am trying to create a "flat" generic list of objects from an object with a list of items in it. Ill explain below:

public class Student
{
   public string Name;
   public string Age;
}

public class Classroom
{
   public string Name;
   public List<Student> Students;
}

I now have a list of Classroom objects called List<Classroom> Classrooms each populated with a list of students, all i need is a generic list that will have the following information for each classroom and every student in all classrooms:

{Classroom.Name, Student.Name, Student.Age}

Thanks in advance.

Answer 1

You could just use SelectMany Linq extension:

Classrooms.SelectMany(classroom => classroom.Students.Select(student => new 
{ 
    ClassroomName = classroom.Name, 
    StudentName = student.Name, 
    StudentAge = student.Age 
}))

Answer 2

You can get what you want like this:

var results = (
    from room in Classrooms
    from student in room.Students
    select new { Room=room.Name, student.Name, student.Age }
).ToList();

This gets you a list of instances of an anonymous type. It might be better to declare a class and use that instead - new MyClass(room.Name, etc) instead of new { Room=room.Name, etc } .