Question

I am trying to get into LINQ to objects as I can see the power of it. Lucky enough I have a question that I think LINQ should be able to solve.

Here is the question (the details are an example);

public class SchoolClass {     public int ID;     public string Name;     public string Teacher;     public string RoomName;      public string Student_Name;     public int Student_Age; } 

As you can see by the example, there is a one to many relationship between the ClassName, Teacher and Room and the Students, i.e. there are potentially many students in the one class.

If we have a List is it possible using LINQ to create a List but have only one instance ID, Name, Teacher, RoomName and an ArrayList of Student_Name and Age?

Producing this:

public class Students {     public string Student_Name;     public int Student_Age; }  public class SchoolClass {     public int ID;     public string Name;     public string Teacher;     public string RoomName;      public ArrayList Students; } 

Essentially, using LINQ to clean the List to a more logical structure?

To give some background to this example. The second structure is used by a DataGrid to produce a Master-Child relationship. We store SchoolClass and StudentInformation in classes as shown above. It would be good use of LINQ to be able to convert our initial List into a structure which can be used by the DataGrid.

Answer 1

I changed the ArrayList to List<Students>, and:

    List<SourceData> source = new List<SourceData>();     //...your data here ;-p     var classes = (from row in source                   group row by new {                           row.ID, row.Name,                           row.Teacher, row.RoomName }                       into grp                       select new SchoolClass                       {                           ID = grp.Key.ID,                           Name = grp.Key.Name,                           Teacher = grp.Key.Teacher,                           RoomName = grp.Key.RoomName,                           Students = new List<Students>(                               from row in grp                               select new Students                               {                                   Student_Age = row.Student_Age,                                   Student_Name = row.Student_Name                               })                       }).ToList();