How do you repopulate a form in ASP.NET MVC that contains a DropDownList?

Question

How do you repopulate a form in ASP.NET MVC that contains a DropDownList?

Answer 1

I believe you are asking how to maintain the value for a dropdown list after a form is submitted and re-displayed. If so, please see below for a VERY SIMPLE example:

Create a new MVC app (using MVC beta) and place the following in HomeController:

private Dictionary<string, string> getListItems()
{
    Dictionary<string, string> d = new Dictionary<string, string>();
    d.Add("Apple", "APPL");
    d.Add("Orange", "ORNG");
    d.Add("Banana", "BNA");
    return d;
}

public ActionResult Index()
{
    Dictionary<string, string> listItems = getListItems();
    SelectList selectList = new SelectList(listItems, "Value", "Key");
    ViewData["FruitDropDown"] = selectList;

    return View();
}

[AcceptVerbs(HttpVerbs.Post)]
public ActionResult Index(FormCollection form)
{

    string selectedItem = form["FruitDropDown"];

    Dictionary<string, string> listItems = getListItems();
    SelectList selectList = new SelectList(listItems, "Value", "Key", selectedItem);
    ViewData["FruitDropDown"] = selectList;

    ViewData["Message"] = "You selected ID:" + selectedItem;

    return View();

}

And place this in Home\Index.aspx in between the MainContent tags:

<div><strong><%= ViewData["Message"] %></strong></div>

<% using (Html.BeginForm()) { %>
<%= Html.DropDownList("FruitDropDown","(select a fruit)") %>
<input type="submit" value="Submit" />
<% } %>

Answer 2

I just wanted to add the BigJoe714 has it right except the ...new SelectList(listItems, "Value", "Key", selectedItem) has the key / value switched

The constructor takes these params for this overload

public SelectList( IEnumerable items, string dataValueField, string dataTextField, object selectedValue );

The data value should be the key while the data text should be the value.

But otherwise, thanks so much! Another kicka$$ feature of asp.net mvc