Question

I am writing a custom validation set that will display all missing elements on a div. I’d like to be able to use a custom @Html.BeginForm() method that will write out that div but I’m really not sure where to even begin as this nut is a little tougher to crack than just a html extension that writes out a Tag or String (the form encapsulates data/controls and is closed by } at the end).

I looked at the metadata version of the built in BeginForm() method and it wasn’t much help to me. Essentially, I just want to extend that method if possible and have it write out a MvcHtmlString of a div that will be show/hidden from JavaScript.

ultimately where I’m struggling is figuring out how to write this custom helper that has the beginning and ending component to it.

@using(Html.BeginForm())
{
...

}

I’d want to be able to do something like this:

@using(Html.VBeginForm())
{
...

}

and have that render my extra html

EDIT: adding code from suggestion below

public class VBeginForm : IDisposable
{
    private readonly HtmlHelper _helper;
    public VBeginForm(HtmlHelper htmlHelper, string areaName)
    {
        _helper = htmlHelper;
        var container = new TagBuilder("form");
        container.GenerateId(areaName);
        var writer = _helper.ViewContext.Writer;
        writer.Write(container.ToString(TagRenderMode.StartTag));
    }

    public void Dispose()
    {
        _helper.ViewContext.Writer.Write("</form>");
    }
}

Answer 1

You need to write an extension method for the HtmlHelper class that prints to helper.ViewContext.Writer.

The method should return an IDisposable that prints the closing tag in its Dispose method.