How to pass Request.QueryString to Url.Action?

Question

I\'m building an url using the method:

Url.Action(\"action\", \"controller\");

I like to pass the querystring for the current request into

Answer 1

If you want to easily be able to add additional route value parameters to your Url.Action, try this extension method (based on Linefeed's) which takes an anonymous object and returns a RouteValueCollection:

public static RouteValueDictionary ToRouteValues(this NameValueCollection col, Object obj)
{
    var values = new RouteValueDictionary(obj);
    if (col != null)
    {
        foreach (string key in col)
        {
            //values passed in object override those already in collection
            if (key != null && !values.ContainsKey(key)) values[key] = col[key];
        }
    }
    return values;
}

Then you can use it like so:

Url.Action("action", "controller", Request.QueryString.ToRouteValues(new{ id=0 }));

Answer 2

The extension method seems correct and is the way to go.

Answer 3

Here's my solution based on pwhe23's answer. I wanted to keep query string parameters through POST requests (due to a Mvc.Grid) and use just a single action for HTTP GET. CRUD actions are handled by a single page and modal dialogs inside (for insert/update/delete).

So here's my Extension:

public static class MvcExtensions
{
    public static RouteValueDictionary ToRouteValues(this NameValueCollection col, Object obj = null)
    {
        var values = obj != null ? new RouteValueDictionary(obj) : new RouteValueDictionary();

        if (col == null) return values;

        foreach (string key in col)
        {
            //values passed in object are already in collection
            if (!values.ContainsKey(key)) values[key] = col[key];
        }
        return values;
    }
}

Usage in Controller (e.g. Edit action):

    [HttpPost]
    public ActionResult Edit(MyModel model)
    {
        // Some stuff
        return RedirectToAction("Index", Request.QueryString.ToRouteValues());
    }

Form for edit generated in View (modal dialog is used):

 @using (Html.BeginForm("Edit", "SomeControllerName", Request.QueryString.ToRouteValues(), FormMethod.Post))
    {
        // Some stuff... e.g. dialog content
    }