Setting selected value in dropdown list

Hello every one i have strange bug with dropdownlist on one of the pages!

I used code 开发者_运维问答such as this for 3 dropdownlists:

//GetTypes returns collection of all availibale types from database 
      ViewData["Types"] = new SelectList(dataManager.IssueTypes.GetTypes(), "Id", "Title", issue.Type);

and it works great!

But when i used it like this:

// GetRoles returns collection of all availibale roles
ViewData["Roles"] = new SelectList(dataManager.Membership.GetRoles(), "RoleId", "RoleName",
                dataManager.Membership.GetUserRole(id));

it always shows default value! I looked trough this code with debuger many times but everithing seems fine! Will be grateful for any kind of help!

View code:

%: Html.DropDownList("RoleId", ViewData["Roles"] as IEnumerable<SelectListItem>)%>

How about using view models instead of ViewData? Everytime I see someone using ViewData I feel myself in the obligation to point this out as personally I consider as best practices.

So start with defining a view model that will be used by your view:

public class RolesViewModel
{
    public string SelectedRoleId { get; set; }
    public IEnumerable<SelectListItem> Roles { get; set; }
}

Now let's move on to the controller action that will populate this view model and pass it to the view:

public ActionResult Foo(string id)
{
    var model = new RolesViewModel
    {
        SelectedRoleId = dataManager.Membership.GetUserRole(id),
        Roles = dataManager.Membership.GetRoles().Select(x => new SelectListItem
        {
            Value = x.RoleId,
            Text = x.RoleName
        })
    };
    return View(model);
}

OK, now you should ensure that SelectedRoleId represents a string value which is present in the Roles collection. This is what will preselect the dropdown list.

And finally the strongly typed view:

<%= Html.DropDownListFor(
    x => x.SelectedRoleId, 
    new SelectList(Model.Roles, "Value", "Text")
)%>

I don't know what type your dataManager.Membershop.GetUserRole(id) returns?

But you need to change the 4th parameter in this call:

ViewData["Roles"] = new SelectList(dataManager.Membership.GetRoles(), "RoleId", "RoleName",
                dataManager.Membership.GetUserRole(id));

To something like:

ViewData["Roles"] = new SelectList(dataManager.Membership.GetRoles(), "RoleId", "RoleName",
                dataManager.Membership.GetUserRole(id).RoleId);

Notice the RoleId at the end? The object you specify as the selected item, should be the value of the item's Value property - not the entire object.