How do I get this ViewModel correct? - asp.net-mvc

Question

Utilizing MVC 5 and Entity Framework I am trying to set up my a ViewModel for my Index view for a show of Employees and their goals.
I have an employee table, an employeeMap table (join table with payload) and a goal table.
There is a one-to-many relationship between Employee and EmployeeMap and between Goal and EmployeeMap.
I am a total newbie and getting stuck with an index view, which initially should display employees, and when one employee is selected should display the goals of the employees.
I can't get my index action right:
var viewModel = new EmployeeGoals();
viewModel.Employees = db.Employees
.Include(d => d.Department)
.Include(e => e.Position)
.Include(m => m.EmployeeMaps)
.Where(d => d.OrganizationID == oid && d.Department.ManagerID == currentUser.EmployeeID)
.OrderBy(d => d.HireDate);
if (id != null)
{
ViewBag.EmployeeID = id.Value;
viewModel.EmployeeMaps = viewModel.Employees.Where(e => e.ID == id.Value).Single().EmployeeMaps;
viewModel.Goals = viewModel.EmployeeMaps.Where(e => e.EmployeeID == ViewBag.EmployeeID).Select(e => e.Goals);
}
if (goalID != null)
{
ViewBag.GoalID = goalID.Value;
viewModel.Activities = viewModel.Goals.Where(
x => x.ID == goalID).Single().Activities;
}
return View(viewModel);
I do get the viewmodel.employees populated correctly, but not the viewmodel.goals
oh, and the viewmodel is:
public class EmployeeGoals
{
public IEnumerable<EmployeeMap> EmployeeMaps { get; set; }
public IEnumerable<Employee> Employees { get; set; }
public IEnumerable<Goal> Goals { get; set; }
}
A hint to help me past this would be great.
Thanks
Got it working using a different approach:
viewModel.Employees = db.Employees
.Include(d => d.Department)
.Include(e => e.Position)
.Include(m => m.EmployeeMaps)
.Where(d => d.OrganizationID == oid && d.Department.ManagerID == currentUser.EmployeeID)
.OrderBy(d => d.HireDate);
if (id != null)
{
ViewBag.EmployeeID = id.Value;
viewModel.EmployeeMaps = viewModel.Employees.Where(e => e.ID == id.Value).Single().EmployeeMaps;
viewModel.Goals = from g in db.Goals
join m in db.EmployeeMaps on g.ID equals m.GoalID
join e in db.Employees on m.EmployeeID equals e.ID
where m.EmployeeID == id.Value
select g;
}
couldn't figure out how to get a result using navigation properties, so ended up with above solution. It does the job, but am I hitting the database too often?? Also, ended up with a mix of LINQ syntax'es - should go with just one of them, I know :-/

Answer 1

You should use SelectMany:
viewModel.Goals = viewModel.EmployeeMaps
.Where(e => e.EmployeeID == ViewBag.EmployeeID)
.SelectMany(e => e.Goals);
because EmployeeMaps.Where() is an IEnumerable, so a Select produces IEnumerable<IEnumerable<Goal>>. SelectMany flattens this into IEnumerable<Goal>.