If I have an Action like this:
public ActionResult DoStuff(List<string> stuff)
{
...
ViewData["stuff"] = stuff;
...
return View();
}
I can hit it with the following URL:
http://mymvcapp.com/controller/DoStuff?stuff=hello&stuff=world&stuff=foo&stuff=bar
But in my ViewPage, I have this code:
<%= Html.ActionLink("click here", "DoMoreStuff", "MoreStuffController", new { stuff = ViewData["stuff"] }, null) %>
Unfortunately, MVC is not smart enough to recognize that the action takes an array, and unrolls the list to form the proper url route. instead it just does a .ToString() on the object which just lists the data type in the case of a List.
Is there a way to get Html.ActionLink to generate a proper URL when one of the destination Action's parameters is an array or list?
-- edit --
As Josh pointed out below, ViewData["stuff"] is just an object. I tried to simplify the problem but instead caused an unrelated bug! I'm actually using a dedicated ViewPage<T> so I have a tightly coupled type aware Model. The ActionLink actually looks like:
<%= Html.ActionLink("click here", "DoMoreStuff", "MoreStuffController", new { stuff = ViewData.Model.Stuff }, null) %>
Where ViewData.Model.Stuff is typed as a List
I'm thinking that a custom HtmlHelper would be in order.
public static string ActionLinkWithList( this HtmlHelper helper, string text, string action, string controller, object routeData, object htmlAttributes )
{
var urlHelper = new UrlHelper( helper.ViewContext.RequestContext );
string href = urlHelper.Action( action, controller );
if (routeData != null)
{
RouteValueDictionary rv = new RouteValueDictionary( routeData );
List<string> urlParameters = new List<string>();
foreach (var key in rv.Keys)
{
object value = rv[key];
if (value is IEnumerable && !(value is string))
{
int i = 0;
foreach (object val in (IEnumerable)value)
{
urlParameters.Add( string.Format( "{0}[{2}]={1}", key, val, i ));
++i;
}
}
else if (value != null)
{
urlParameters.Add( string.Format( "{0}={1}", key, value ) );
}
}
string paramString = string.Join( "&", urlParameters.ToArray() ); // ToArray not needed in 4.0
if (!string.IsNullOrEmpty( paramString ))
{
href += "?" + paramString;
}
}
TagBuilder builder = new TagBuilder( "a" );
builder.Attributes.Add("href",href);
builder.MergeAttributes( new RouteValueDictionary( htmlAttributes ) );
builder.SetInnerText( text );
return builder.ToString( TagRenderMode.Normal );
}