Templated Razor Delegates – Phil Haack

Posted by nmarun on ASP.net Weblogs See other posts from ASP.net Weblogs or by nmarun
Published on Mon, 28 Feb 2011 13:38:41 GMT Indexed on 2011/02/28 15:25 UTC
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This post is largely based off of Phil Haack’s article titled Templated Razor Delegates. I strongly recommend reading this article first. Here’s a sample code for the same, so you can have a look at. I also have a custom type being rendered as a table.

   1: // my custom type
   2: public class Device
   3: {
   4:     public int Id { get; set; }
   5:     public string Name { get; set; }
   6:     public DateTime MfgDate { get; set; }
   7: }

Now I can write an extension method just for this type.

   1: public static class RazorExtensions
   2: {
   3:     public static HelperResult List(this IList<Models.Device> devices, Func<Models.Device, HelperResult> template)
   4:     {
   5:         return new HelperResult(writer =>
   6:         {
   7:             foreach (var device in devices)
   8:             {
   9:                 template(device).WriteTo(writer);
  10:             }
  11:         });
  12:     }
  13:     // ...
  14: }

Modified my view to make it a strongly typed one and included html to render my custom type collection in a table.

   1: @using TemplatedRazorDelegates
   2: @model System.Collections.Generic.IList<TemplatedRazorDelegates.Models.Device>
   3:  
   4: @{
   5:     ViewBag.Title = "Home Page";
   6: }
   7:  
   8: <h2>@ViewBag.Message</h2>
   9:  
  10: @{
  11:   var items = new[] { "one", "two", "three" };
  12:   IList<int> ints = new List<int> { 1, 2, 3 };
  13: }
  14:  
  15: <ul>
  16: @items.List(@<li>@item</li>)
  17: </ul>
  18: <ul>
  19: @ints.List(@<li>@item</li>)
  20: </ul>
  21:  
  22: <table>
  23:     <tr><th>Id</th><th>Name</th><th>Mfg Date</th></tr>
  24:     @Model.List(@<tr><td>@item.Id</td><td>@item.Name</td><td>@item.MfgDate.ToShortDateString()</td></tr>)
  25: </table>

We get intellisense as well!

image

Just added some items in the action method of the controller:

   1: public ActionResult Index()
   2: {
   3:     ViewBag.Message = "Welcome to ASP.NET MVC!";
   4:     IList<Device> devices = new List<Device>
   5:                                 {
   6:                                     new Device {Id = 1, Name = "abc", MfgDate = new DateTime(2001, 10, 19)},
   7:                                     new Device {Id = 2, Name = "def", MfgDate = new DateTime(2011, 1, 1)},
   8:                                     new Device {Id = 3, Name = "ghi", MfgDate = new DateTime(2003, 3, 15)},
   9:                                     new Device {Id = 4, Name = "jkl", MfgDate = new DateTime(2007, 6, 6)}
  10:                                 };
  11:     return View(devices);
  12: }

Running this I get the output as:

image

Absolutely brilliant! Thanks to both Phil Haack and to David Fowler for bringing this out to us. Download the code for this from here.

Verdict: RazorViewEngine.Points += 1;

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