Retaining RouteData in Html.BeginForm()

Question

I have been using a variant of the Html.BeginForm() method to attach an html attribute to my form, like this :

@using (Html.BeginForm("actionname", "controllername", FormMethod.Post, new { id = "myform" }))

Unfortunately this causes the form target to loose all route data.

Say my url was controller/action?abc=123, then using Html.BeginForm() generates the form post target as controller/action?abc=123 but the overloaded version (which I am using to add the html id attribute to the form), generates the target as controller/action (which actually is understandable, since I am specifying the route myself, but it doesn't solve my purpose).

Is there a variant of the Html.BeginForm() which would allow me retain the old route values and let me add html attributes to the form at the same time?

Answer 1

As far as I can see, only the parameterless version of BeginForm uses the current full URL.

public static MvcForm BeginForm(this HtmlHelper htmlHelper) {
    // generates <form action="{current url}" method="post">...</form>
    string formAction = htmlHelper.ViewContext.HttpContext.Request.RawUrl;
    return FormHelper(htmlHelper, formAction, FormMethod.Post, new RouteValueDictionary());
}

---

I'm not sure if this is the best way, but you could write a custom form helper to include the QueryString values:

public static class MyFormExtensions
{
    public static MvcForm MyBeginForm(this HtmlHelper htmlHelper, object htmlAttributes)
    {
        var rvd = new RouteValueDictionary(htmlHelper.ViewContext.RouteData.Values);
        var queryString = htmlHelper.ViewContext.HttpContext.Request.QueryString;
        foreach (string key in queryString.AllKeys) rvd.Add(key, queryString[key]);
        return htmlHelper.BeginForm(null, null, rvd, FormMethod.Post, HtmlHelper.AnonymousObjectToHtmlAttributes(htmlAttributes));
    }
}

@using (Html.MyBeginForm(new { id = "myform" }))
{
    //...
}