asp.net-mvc - creating html helper extension to pass view data

Question

This may be a bit moot, but it is something I want to do just for the sake of seeing how, and I think it is a little cleaner than the typical method.

Right now, I can pass extra ViewData to a partial view like this;

@Html.Partial( "path/to/partial", new ViewDataDictionary{{ "key", "value" }})

And that works fine, though I was wondering, would it be possible to make an extension method that would just clean it up a bit? I've tried to do it for a few hours now and am finding myself a bit lost, but I am attempting to go the route of ..

@Html.Partial( "path/to/partial" ).With("key","data").With("key2","data2")

So basically, it's just syntax sugar. But I haven't been able to get this to work. Has anyone else achieved something similar?

Update

I actually may have solved this myself. I had to turn the idea upside down to get the result I want. I'm not sure if I'll even use it, given how obtuse it is, but it was interesting to learn about! I am very welcoming to any insight that could be used to make this better. But essentially, the trick was to do it in reverse.

using System;
namespace System.Web.Mvc.Html {
    public static partial class PartialViewExtensions {
        /// <summary>
        /// An Html Helper specifically for rendering a partial view with a fluently declared ViewDataDictionary.
        /// </summary>
        public class PartialHtmlHelper : HtmlHelper
        {
            public PartialHtmlHelper(ViewContext viewContext, IViewDataContainer viewDataContainer) 
                : base(viewContext, viewDataContainer) { }  
        }

        /// <summary>
        /// Prepare the upcoming partial view with view data.
        /// </summary>
        public static PartialHtmlHelper With( this HtmlHelper helper, string key, dynamic value ) {
            var partial = new PartialHtmlHelper( helper.ViewContext, helper.ViewDataContainer );
            partial.ViewData.Add( key, value );
            return partial;
        }

        /// <summary>
        /// Prepare the upcoming partial view with view data.
        /// </summary>
        public static PartialHtmlHelper With( this PartialHtmlHelper helper, string key, dynamic value ) {
            helper.ViewData.Add( key, value ); return helper;
        }

        /// <summary>
        /// Render a prepared partial view with readied view data.
        /// </summary>
        public static MvcHtmlString Using( this PartialHtmlHelper helper, string partialViewName ) {
            return helper.Partial( partialViewName, helper.ViewData );
        }
    }
}

And that makes it very easy to declare with fluent, chained methods.

@Html
   .With("alpha", "alpha.property" )
   .With("beta", "beta.property" )
   .With("gamma", "gamma.property")
   .With("epsilon", DateTime.UtcNow() )
   .With("sigma", "sigma.property" )
   .Using("Templates/Form/Slots")

Yeah, that is my goal. I essentially would love to declare each item in the dictionary as a chain of extensions, and then the whole thing gets rendered as if I had done it the original way. I know it sounds silly, but it is just the kind of way I like to code. If I'm going to use the helpers, I at least want them to feel fluent. — Ciel
– Ciel, Commented Sep 17, 2014 at 22:09
Unfortunately, I don't have any code for the With method yet. I'm still stuck trying to figure out what to attach it to. I thought attaching it to MvcHtmlString would work, but that doesn't seem to behave like I thought. — Ciel
– Ciel, Commented Sep 17, 2014 at 22:10
The problem is, the MvcHtmlString class hierarchy doesn't contain much functionality that will help you here (all it appears to do is give you a ToHtmlString() method). You might be better off writing your own Partial() extension method, wrapping one of the existing Partial() methods. — Robert Harvey
– Robert Harvey, Commented Sep 17, 2014 at 22:18

Mohsen Esmailpour · Accepted Answer · 2014-09-17 23:06:38Z

1

Hence Html.Partial is an extension method so you can't add an extension method to an extension method.

edited Sep 17, 2014 at 23:06

answered Sep 17, 2014 at 22:43

Mohsen Esmailpour

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1 Comment

Ciel Over a year ago

You're right. So I just turned it upside down. I added the answer I came to up above, just now. I'm not sure if it really serves any useful purpose, but it was an interesting thing to dig into.

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