ASP.NET MVC dropdownlist

Question

Can someone point me to an article that shows the dropdownlist being populated from linq to sql (text and value being set).

Thanks Danny

Answer 1

Now that the HtmlHelper extension takes an IEnumerable<SelectListItem>, I don't create SelectList's, but usually just create the SelectListItems with LINQ.

Controller

ViewData["CategoryID"] = categories.Select( c => new SelectListItem
                                                 {
                                                     Text = c.CategoryName,
                                                     Value = c.CategoryID
                                                 }
                                          );

View

<%= Html.DropDownList("CategoryID") %>

or if I want a default selection

<%= Html.DropDownList("CategoryID",
                      (IEnumerable<SelectListItem>)ViewData["CategoryID"],
                      "Select a Category" ) %>

EDIT:

The interesting bit about the dropdown list is that you need to supply a range of values from which to select a single value that fits into your actual data model. I typically provide the range (menu items) via view data and expect back the model values when the page is posted. If you wanted strongly-typed menus as well, you'd need to provide a view-only model that encapulates your real model and any menus. This would involve, on posting, the use of prefixes to identify the model elements. The trade-off, to my mind, is simpler model binding on post vs. the use of strongly-typed menus in the view. I'm not hung up on the latter, so I opt not to put my menus in the model. If you wanted to do this, though, it might look like the following.

Model

public class CategoryViewModel
{
    public Category Category { get; set; }
    public IEnumerable<SelectListItem> CategoryMenu { get; set; }
    ...
}

Controller

Display action

var model = new CategoryViewModel();
model.CategoryMenu = categories.Select( c => new SelectListItem
                                                 {
                                                     Text = c.CategoryName,
                                                     Value = c.CategoryID
                                                 }
                                      );

...
return View(model);

Create action

[AcceptVerbs( HttpVerbs.Post )]
public ActionResult Create( [Bind(Prefix="Category")]Category category )
{
   ...
}

View

<%= Html.TextBox("Category.Name") %>

<%= Html.DropDownList("Category.CategoryID",
                      Model.CategoryMenu,
                      "Select a Category" ) %>

Answer 2

Here's one great article by Rob Connery

Controller Code

NorthwindDataContext db = new NorthwindDataContext();
var categories = from c in db.Categories select c;
ViewData["CategoryID"] = new SelectList(categories, "CategoryID", "CategoryName");

View Markup

<%=Html.DropDownList("CategoryID")%>