Simplest Way To Do Dynamic View Models in ASP.NET MVC 3

Question

Caveat: This might be an inappropriate use of C#'s dynamic keyword and I probably should be using a strongly-typed view model, but...

I'm trying to avoid creating a strongly-typed view model by passing a C# 4 dynamic type to my view. I have this in my controller:

    public ActionResult Index()
    {
        var query =
            from fr in db.ForecastRates
            join c in db.Codes
            on 
                new { Code = fr.RateCode, CodeType = "ForecastRate" }
            equals 
                new { Code = c.CodeValue, CodeType = c.CodeType }
            select new
            {
                RateCode = fr.RateCode,
                RateCodeName = c.CodeName,
                Year = fr.Year,
                Rate = fr.Rate,
                Comment = fr.Comment
            };

        // Create a list of dynamic objects to form the view model
        // that has prettified rate code
        var forecastRates = new List<dynamic>();

        foreach (var fr in query)
        {
            dynamic f = new ExpandoObject();

            f.RateCode = fr.RateCode;
            f.RateCodeName = fr.RateCodeName;
            f.Year = fr.Year;
            f.Rate = fr.Rate;
            f.Comment = fr.Comment;

            forecastRates.Add(f);
        }

        return View(forecastRates);
    }

...and this in my view (I'm using MVC 3's Razor view engine):

        @inherits System.Web.Mvc.WebViewPage<IEnumerable<dynamic>>

        ...

        <tbody>
            @foreach (var item in Model) {
            <tr>
                <td>@item.RateCodeName</td>
                <td>@item.Year</td>                            
                <td>@item.Rate</td>
                <td>@item.Comment</td>
            </tr>
            }
        </tbody>

I don't like how I iterate through the LINQ result to form the List of dynamic objects.

I'd like to initialize each ExpandoObject inside the LINQ query, but that doesn't seem to be supported.

I tried casting the the query result as List, but that didn't work because you can't convert anonymous type to dynamic.

Solution

Like you said, it's not supported. (I'm not saying dynamic View Models aren't supported - I'm saying what you're trying to do is not)

You could probably neaten up the LINQ query, but in the end your best bet would be to simply create a custom View Model. Seriously, it will take you about 30 seconds to do that.

I know dynamic is new and cool and everything, but your code will be a lot neater and easier to maintain if you just stick with a custom View Model in this case.

I would only go with a dynamic View Model in the very simple scenarios - most of the time you probably want to stick with what we've been doing all along - custom View Models.