ASP.Net Passing ViewModel to View (Underlying entity framework)

Question

I am having problems passing a ViewModel into a view.

My ViewModel:

namespace ImpactDBASPNet.Models
{
    public class ComputerInfoViewModel
    {
        public List<string> CompanyList { get; set; }
        public tbl_computerinfo entitymodeleffort { get; set; }
    }
}

Controller:

    public ActionResult Index()
    {
        var tbl_computerinfo = db.tbl_computerinfo.Include(t => t.tbl_equipment);
        tbl_computerinfo = tbl_computerinfo.Where(c => c.Company == "Test Company");

        List<string> companylist = new List<string>();
        companylist.Add("Hello1");
        companylist.Add("hello2");

        ComputerInfoViewModel model = new ComputerInfoViewModel();
        model.CompanyList = companylist;
        model.entitymodeleffort = tbl_computerinfo;

        return View(model);
    }

I'm doing this primarily because I need to pass a list for a dropdownlist in my view, so I need to pass in the entity framework model AND the list. The error I am getting is:

Error   1   Cannot implicitly convert type 'System.Linq.IQueryable<ImpactDBASPNet.Models.tbl_computerinfo>' to 'ImpactDBASPNet.Models.tbl_computerinfo'. An explicit conversion exists (are you missing a cast?)    c:\impactdbaspnet\controllers\tbl_computerinfocontroller.cs 31  39  ImpactPortal

Answer 1

Property entitymodeleffort is typeof tbl_computerinfo but you assigning IEnumerable<tbl_computerinfo> to it, resulting in the error. You need to use FirstOrDefault() (or one of the variants - Single() etc.) that returns a single tbl_computerinfo object.

Change the code to

public ActionResult Index()
{
  var tbl_computerinfo = db.tbl_computerinfo
   .Include(t => t.tbl_equipment)
   .Where(c => c.Company == "Test Company")
   .FirstOrDefault();
  List<string> companylist = new List<string>() { "Hello1", "Hello2" }; // save a few lines of code
  ComputerInfoViewModel model = new ComputerInfoViewModel();
  model.CompanyList = companylist;
  model.entitymodeleffort = tbl_computerinfo;
  return View(model);
}

Side note: Since companylist is used for a dropdownlist , you can make the property SelectList

public SelectList CompanyList { get; set; }

and

model.CompanyList = new SelectList(companylist);

and in the view

@Html.DropDownListFor(m => m.entitymodeleffort.SomeProperty, Model.CompanyList, ...)