DropDownListFor and showing a SelectedValue

Question

I have been banging my head for 2 days now with Html.DropDownListFor and MVC3.

I have been successful in creating a drop down list and successfully updating the database based on it.

I create a drop down list for area

1 - NewYork
2 - London
3 - Paris
etc

The problem occurs when creating a edit page where the user can change the previous choice. I am trying to show the previous selected value in the drop down.

My code is as follows:

Controller:

//
// GET: /MyHome/UpdateProfile

public ActionResult UpdateProfile()
{
    var userProfile = websiteRepository.GetProfileForLoggedUser();
    UpdateProfileViewModel viewModel = new UpdateProfileViewModel
    {
       AreaLookUps = websiteRepository.GetAreaLookUpSelectList(userProfile.Area),
       UserProfile = userProfile
    };
    return View("UpdateProfile", viewModel);
}

The GetAreaLookUpSelectList method

public IEnumerable<SelectListItem> GetAreaLookUpSelectList(int selectedId)
{
   var areaLookUps = from p in db.AreaLookUp
                     orderby p.AreaLookUpDescription
                     select new SelectListItem
                     {
                        Text = p.AreaLookUpDescription,
                        Value = SqlFunctions.StringConvert((double)p.AreaLookUpId),
                        Selected = p.AreaLookUpId == selectedId
                     };
    return areaLookUps;
}

View

@model NPLHWebsite.ViewModels.UpdateProfileViewModel

<div class="editor-label">
   @Html.LabelFor(model => model.UserProfile.Area)
   @Html.DropDownListFor(model => model.UserProfile.Area, Model.AreaLookUps, "--Select Area--")
</div>

ViewModel

public class UpdateProfileViewModel
{
   public UserProfile UserProfile { get; set; }
   public IEnumerable<SelectListItem> AreaLookUps { get; set; }
}

Please help me display a selected value. Say "London" in the dropdownlist, if that option was selected while creating the profile. The database stores the value of 2 to represent London.

Darin Dimitrov Darin Dimitrov · Accepted Answer · 2012-10-27T16:36:46

It looks like the AreaLookUpId property is a double which is causing issues when comparing with the selected value because you are using SqlFunctions.StringConvert and the format might not match exactly.

I would recommend you using integers or guids for id properties. Also you can remove the Selected = p.AreaLookUpId == selectedId from your GetAreaLookUpSelectList function. It is enough to set the viewModel.UserProfile.Area property in your controller action to the corresponding value (which you have already done):

public IEnumerable<SelectListItem> GetAreaLookUpSelectList(int selectedId)
{
    return db
        .AreaLookUp
        .OrderBy(x => x.AreaLookUpDescription)
        .ToList()
        .Select(x => new SelectListItem 
        {
            Value = x.AreaLookUpId.ToString(),
            Text = x.AreaLookUpDescription
        });
}

DropDownListFor and showing a SelectedValue

1 Answers