Question

I have three domain objects:

Child, Classroom and ChildClassroom. Here are lists of each:

var childrens = new List<Child>() {
    new Child() { ChildId = 1, FirstName = "Chris" },
    new Child() { ChildId = 2, FirstName = "Jenny" },
    new Child() { ChildId = 3, FirstName = "Dave"  },
};

var classrooms = new List<Classroom>() {
   new Classroom() { ClassroomId = 1, FullName = "Kindergarten" },
   new Classroom() { ClassroomId = 2, FullName = "Elementary"   },
   new Classroom() { ClassroomId = 3, FullName = "Secondary"    },
};

var childclassrooms = new List<ChildClassroom>() {
   new ChildClassroom() { ClassroomId = 1, ChildId = 1 },
   new ChildClassroom() { ClassroomId = 2, ChildId = 1 },
   new ChildClassroom() { ClassroomId = 3, ChildId = 2 },
};

What I want is:

 var childClassroomRelationships = new object[] {
     new {
         childid = 1,
         classrooms = new object[] {
            new { classroomId = 1, occupied = true  },
            new { classroomId = 2, occupied = true  },
            new { classroomId = 3, occupied = false }
     },
     ...
 };

What’s the way to go about this in Linq?

Answer 1

var kidsInClass = (
    from kid in childrens
    from c in classrooms
    select new {
        ChildID = kid.ChildId,
        classrooms = (
            from cc in childclassrooms
            select new {
                ClassroomID = c.ClassroomId,
                Occupied = cc.ChildId == kid.ChildId
            }).ToArray()
    }).ToArray();