Question

I’m trying to implement a paging and sorting list in ASP.NET MVC without using MVContrib grid or javascript (needs to be seo friendly).

I have constructed my action with the following signature:

ActionResult List(int? page, string sort, string direction);

The problem I have though is getting both the paging and the sorting to work. Say for example I have the following code:

<%= Html.ActionLink("Title", "List", new { sort = "Title", direction = "ASC" }) %>

I hoped this would generate a url containing all of the existing route values (including the current page) but it doesn’t. Therefore when you click on the link the page is set back to null.

I have looked at all the overloads for the ActionLink helper but nothing looks like it will help. What I effectively need to do is generate a url/link with the existing page value (or potentially any other route values) and the new sort parameters.

I’d appreciate it if someone could help. Thanks.

Answer 1

Problem solved. I managed to come up with the following extension methods:

public static class ActionLinkExtensions
{
    public static MvcHtmlString ActionLink(this HtmlHelper helper, string linkText, string actionName, bool addExistingRouteValues)
    {
        return ActionLink(helper, linkText, actionName, null, null, addExistingRouteValues, null);
    }

    public static MvcHtmlString ActionLink(this HtmlHelper helper, string linkText, string actionName, object routeValues, bool addExistingRouteValues)
    {
        return ActionLink(helper, linkText, actionName, null, routeValues, addExistingRouteValues, null);
    }

    public static MvcHtmlString ActionLink(this HtmlHelper helper, string linkText, string actionName, string controllerName, object routeValues, bool addExistingRouteValues, object htmlAttributes)
    {
        var queryString = helper.ViewContext.HttpContext.Request.QueryString;
        var newRouteValues = routeValues == null ? helper.ViewContext.RouteData.Values : new RouteValueDictionary(routeValues);

        if (addExistingRouteValues)
        {
            foreach (string key in queryString.Keys)
            {
                if (!newRouteValues.ContainsKey(key))
                    newRouteValues.Add(key, queryString[key]);
            }
        }

        return MvcHtmlString.Create(HtmlHelper.GenerateLink(helper.ViewContext.RequestContext, helper.RouteCollection, linkText, null, actionName, controllerName, newRouteValues, new RouteValueDictionary(htmlAttributes)));
    }
}

Now all you have to do is add true at the end of your helper and the existing route values will be added. Hope this helps.