Create using for own helper? like Html.BeginForm

Question

I was wondering, is it possible to create your own helper definition, with a using? such as the following which creates a form:

using (Html.BeginForm(params)) 
{
}

I'd like to make my own helper like that. So a simple example I'd like to do

using(Tablehelper.Begintable(id)
{
    <th>content etc<th>
}

which will output in my view

<table>
  <th>content etc<th>
</table>

Is this possible? if so, how?

Thanks

Darin Dimitrov · Accepted Answer · 2011-10-28 11:33:16Z

20

Sure, it's possible:

public static class HtmlExtensions
{
    private class Table : IDisposable
    {
        private readonly TextWriter _writer;
        public Table(TextWriter writer)
        {
            _writer = writer;
        }

        public void Dispose()
        {
            _writer.Write("</table>");
        }
    }

    public static IDisposable BeginTable(this HtmlHelper html, string id)
    {
        var writer = html.ViewContext.Writer;
        writer.Write(string.Format("<table id=\"{0}\">", id));
        return new Table(writer);
    }
}

and then:

@using(Html.BeginTable("abc"))
{
    @:<th>content etc<th>
}

will yield:

<table id="abc">
    <th>content etc<th>
</table>

I'd also recommend you reading about Templated Razor Delegates.

edited Oct 28, 2011 at 11:33

answered Oct 28, 2011 at 11:25

Darin Dimitrov

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6 Comments

Ron Sijm Over a year ago

Ok, thanks. Since you did this in a class, I assume it isnt possible with a regular @helper Method()? Also, where do I place this? I tried just putting it in my app_code folder with the rest of the helpers, but that did not seem to work.

Darin Dimitrov Over a year ago

@RonSijm, you could place this class in a HtmlExtensions.cs file inside an Extensions folder for example. Just make sure that you bring the namespace into which this class is defined into scope in your view so that you can have access to the extension method: @using AppName.Extensions.

Ron Sijm Over a year ago

thanks, that seems to work. Too bad it does not work just putting the using in _layout.cshtml though.

Darin Dimitrov Over a year ago

@RonSijm, you could add the namespace to the <namespaces> section of ~/Views/web.config file (not ~/web.config). This way the helper will be universally available within your application. Or simply change its namespace to System.Web.Mvc.Html which is where all standard helpers are defined.

Romias Over a year ago

One thing to note... you should override the ToString() returning empty in the Table class... if not you will see the a text like YourDomain.HtmlExtensions.Table a long with the table.

|

Marc Gravell · Accepted Answer · 2011-10-28 11:27:53Z

0

Yes it is; however, to use Tablehelper.* you would need to subclass the base-view and add a Tablehelper property. Probably easier, though, is to add an extension method to HtmlHelper:

public static SomeType BeginTable(this HtmlHelper html, string id) {
    ...
}

which will allow you to write:

using (Html.BeginTable(id))
{
    ...
}

but this will in turn require various other bits of plumbing (to start the element at BeginTable, and end it in Dispose() on the returned value).

answered Oct 28, 2011 at 11:27

Marc Gravell

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