query nested objects with LINQ

Question

I have an instance object of Division class.

Division object holds a list of Branch objects.
Each branch object holds a list of Department objects.
Each Department object holds list of Team objects.

just to make it clear I can do that:

int MakeItClear = DivisionObject.ListOfBranches[5]
                                .ListOfDepartments[4]
                                .ListOfTeam[3]
                                .SomeIntegerProperty;

Each object has ID and Name properties

My wish is create a function that will return a list of team names by passing a parameter of Branch.ID using LINQ.

basically I want to do that using LINQ:

public static List<string> getBranchTeamNames(ref Sales.Division obj, int BranchID)
{
    List<string> result = new List<string>();
    foreach (Sales.Branch b in obj.allBranches)
    {
        if (b.branchID == BranchID)
        {
            foreach (Sales.Department d in b.allDepartmentsManagers)
            {
                foreach (Sales.Team t in d.allTeams)

                {
                    result.Add(t.teamName);
                }
            }

             break;
        }          
    }
    return result;
}

i will be happy for some guidance, does not matter if its c# or vb.net.

thank you for your time and consideration.

Answer 1

Try this:

return obj.allBranches
    .Where(x => x.branchID == BranchID)
    .SelectMany(x => x.allDepartmentsManagers)
    .SelectMany(x => x.allTeams)
    .Select(x => x.teamName)
    .ToList()