Razor, MVC4, @html.dropdownlistfor problems

Question

I'm trying to create a drop down list that populates from a database. I have:

public class Employee
    {
        [Key]
        public int Id { get; set; }
        [Required]
        public String FirstName { get; set; }
        [Required]
        public String LastName { get; set; }
        [Required]
        public String JobTitle { get; set; }
    }

    public class Project
    {
        [Key]
        public int Id { get; set; }
        [Required]
        public String ProjectName { get; set; }
        [Required]
        public String CompanyName { get; set; }
    }

    public class ProjectHour
    {
        [Key]
        public int Id { get; set; }
        [Required]
        public decimal Hours { get; set; }
        [Required]
        public DateTime Date { get; set; }
        public virtual ICollection<Employee> employeeId { get; set; }
        public virtual ICollection<Project> projectId { get; set; }
    }

What I want is to create a form that will create new project hours associated with a project and an employee. I'm trying to use dropdownlists to display the employees and the projects on the create form. Obviously, I'm completely new at this, but what I have so far is:

[HttpPost]
     public ActionResult CreateProjectHour(ProjectHour newProjectHour)
     {
             using (var db = new TimesheetContext())
             {
                 IEnumerable<SelectListItem> emp = db.Employees
                  .Select(c => new SelectListItem
                  {
                      Value = c.Id.ToString(),
                      Text = c.LastName
                  });
                 ViewBag.EmployeeId = emp;

                 db.ProjectHours.Add(newProjectHour);
                 db.SaveChanges();
             }

             return RedirectToAction("ProjectHourList");
         }
     }

And on the form:

@model TimesheetMVC.Models.ProjectHour
...
@Html.DropDownListFor(model => model.employeeId, (SelectList)ViewBag.EmployeeId)

Which is apparently horribly wrong. Any help would be much appreciated...!

Answer 1

Don't use the same name EmployeeId. You need 2 things to create a dropdown list in ASP.NET MVC: a scalar property that will hold the selected value and a collection property that will contain the possible values. But since you are using the ViewBag (which I totally recommend against) you could do the following:

ViewBag.Employees = emp;

and in your view:

@Html.DropDownListFor(
    model => model.employeeId, 
    (IEnumerable<SelectListItem>)ViewBag.Employees
)

But as I said this is not at all an approach that I recommend. I recommend using view models. So define an IEnumerable<SelectListItem> property on your view model:

public IEnumerable<SelectListItem> Employees { get; set; }

and in your controller populate this view model property and then make your view strongly typed to the view model.

Answer 2

Or you could just do a in the controller

SelectList selectList = new SelectList(db.Employees, "Id", "LastName");
ViewBag.EmployeeList = selectList;

and in the View

@Html.DropDownBoxFor(model => model.id_Employee, ViewBag.EmployeeList as SelectList)

I find this approach easier.