Calling Html.BeginForm and specifying action - asp.net-mvc

Question

I have been trying to do the following but whatever I try I just keep getting different errors:
#using (Html.BeginForm(Url.Action(this.ViewContext.RouteData.Values["action"] as string)))
This for example produces:
<form action="/adminTests/create?Length=22" method="post">
Has anyone figured out how to do this?

Answer 1

You are using a wrong overload. It should be:
#using (Html.BeginForm(new { action = ViewContext.RouteData.Values.GetRequiredString("action") }))
or:
#using (Html.BeginForm(ViewContext.RouteData.Values.GetRequiredString("action"), ViewContext.RouteData.Values.GetRequiredString("controller"))))
or if you want to generate a form POSTing to the current url use simply (note that this will include any query string parameters):
#using (Html.BeginForm())
For full list of available overloads consult the documentation.

Answer 2

Perhaps try this:
#using (Html.BeginForm("action", "controller"))
This uses the correct overload and has a simpler (imo) syntax.

Answer 3

Edge case answer
If you are posting back to an action of the same name, but you loaded the form with more data from the route you have to do one more thing. In your controller, you need to remove the extra routing values.
RouteData.Values.Remove("CompanyId");
Let me explain.
In my case I was loading the Add Contact form passing it the company id in the route, e.g., contact/add/123 to the Add action public IActionResult Add(int companyId). The Add/Edit contact form is then loaded with a new ViewModel with the CompanyId populated. var model = new ContactViewModel { CompanyId = companyId };
The route now serves no purpose, but if you try to use Html.BeginForm("add", "contact") the form will still have an action of contact/add/123, which will cause the routing to fail.
You can work around this by taking the id on the add and ignoring it (yuk!). Or by passing parameters rather than using routing (probably best), but sometimes there are external reasons that's not an option and you have to work with the situation you have.
The Action in one go for easier reading
[HttpGet]
[Route("add/{companyId}")]
public IActionResult Add(int companyId)
{
var model = new ContactViewModel { CompanyId = companyId };
RouteData.Values.Remove("companyId");
return PartialView("_ContactModal", model);
}
[HttpPost]
[Route("add")]
public IActionResult Add(ContactViewModel model)
{
...
}