# Monday, November 14, 2011

ASP.NET MVC has an HTML Helper DropDownListFor that takes an IEnumerable and creates a drop down list for it.  Often you want to create a drop down list for an Enum.  Of course you can do this without using an HTML Helper and use standard HTML controls but you don’t have the standard clean view code that HTML Helpers give you.  Extending and creating your own HTML Helpers is rather easy, as demonstrated in my last post. With that in mind I created an extension to DropDownListFor that will create a drop down list for an Enum type.


Enum Html Helper
  1. using System.Collections.Generic;
  2. using System.Linq;
  3. using System.Linq.Expressions;
  4. using DropDownListForEnumDemo.Extensions;
  6. namespace System.Web.Mvc.Html {
  8.     public static class EnumHtmlHelper {
  10.         public static MvcHtmlString DropDownListFor<TModel, TEnum>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TEnum>> expression) {
  11.             return DropDownListFor(htmlHelper, expression, null, null);
  12.         }
  14.         public static MvcHtmlString DropDownListFor<TModel, TEnum>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TEnum>> expression, string optionLabel) {
  15.             return DropDownListFor(htmlHelper, expression, optionLabel, null);
  16.         }
  18.         public static MvcHtmlString DropDownListFor<TModel, TEnum>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TEnum>> expression, object htmlAttributes) {
  19.             return DropDownListFor(htmlHelper, expression, null, htmlAttributes);
  20.         }
  22.         public static MvcHtmlString DropDownListFor<TModel, TEnum>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TEnum>> expression, string optionLabel, object htmlAttributes) {
  23.             ModelMetadata metadata = ModelMetadata.FromLambdaExpression(expression, htmlHelper.ViewData);
  24.             Type enumType = Nullable.GetUnderlyingType(typeof (TEnum)) ?? typeof (TEnum);
  25.             IEnumerable<TEnum> enumValues = Enum.GetValues(enumType).Cast<TEnum>();
  26.             IEnumerable<SelectListItem> items = enumValues.Select(e => new SelectListItem {Text = e.ToString().FromCamelToProperCase(), Value = e.ToString(), Selected = e.Equals(metadata.Model)});
  27.             if (optionLabel != null) {
  28.                 new[] {new SelectListItem {Text = optionLabel}}.Concat(items);
  29.             }
  30.             return htmlHelper.DropDownListFor(expression, items, optionLabel, htmlAttributes);
  31.         }
  32.     }
  33. }


  1. namespace DropDownListForEnumDemo.Enumerations {
  3.     public enum Cars {
  4.         FerrariItalia = 0,
  5.         LamborghiniGallardoLP560,
  6.         LamborghiniAventador,
  7.         AstonMartinVantage,
  8.         Porsche911GT2,
  9.     }
  10. }


  1. namespace DropDownListForEnumDemo.Models {
  3.     public class CarsModel {
  4.         [Display(Name = "Select A Car:")]
  5.         [Required(ErrorMessage = "* Required")]
  6.         public Cars? SelectedCar { get; set; }
  7.     }
  8. }


  1. @{ViewBag.Title = "Home Page";}
  2. @using DropDownListForEnumDemo.Models
  3. @model CarsModel
  4. <h2>@ViewBag.Message</h2>
  5. @using (Html.BeginForm()) {
  6.     <div>
  7.         <fieldset>
  8.             <div class="editor-label">
  9.                 @Html.LabelFor(m => m.SelectedCar)
  10.             </div>
  11.             <div class="editor-field">
  12.                 @Html.DropDownListFor(m => m.SelectedCar, "-- Select --")
  13.                 @Html.ValidationMessageFor(m => m.SelectedCar)
  14.             </div>
  15.         </fieldset>
  16.         <input type="submit" value="Click Me"/>
  17.     </div>
  18. }




Note:  Because enumeration values have to adhere to the same naming conventions as variables I had to work some magic to get the display values formatted correctly.  OK, it’s really not magic…just a little RegEx Voo-Doo.

The code is available on GitHub

posted on Monday, November 14, 2011 8:46:32 AM (Central Standard Time, UTC-06:00)  #    Comments [3]
# Monday, November 07, 2011

ASP.NET MVC provides a lot of HTML Helpers that allow you to more easily with less code create your views.  Typically navigation in MVC is done using the ActionLink HTML Helper that allows you easily generate an html anchor tag that will redirect to a specified controller and action.  I found cases where I wanted my navigation to be done via a button rather than a link so I created my own HTML Helper to make this easier.


  1. using System.Web.Routing;
  3. namespace System.Web.Mvc.Html {
  5.     public static class ActionLinkButtonHelper {
  7.         public static MvcHtmlString ActionLinkButton(this HtmlHelper htmlHelper, string buttonText, string actionName, string controllerName, RouteValueDictionary routeValues) {
  8.             string href = UrlHelper.GenerateUrl("default", actionName, controllerName, routeValues, RouteTable.Routes, htmlHelper.ViewContext.RequestContext, false);
  9.             string buttonHtml = string.Format("<input type=\"button\" title=\"{0}\" value=\"{0}\" onclick=\"location.href='{1}'\" class=\"button\" />",buttonText,href);
  10.             return new MvcHtmlString(buttonHtml);
  11.         }
  12.     }
  13. }

Example Usage:

  1. @Html.ActionLinkButton("Add", "AddSiteFromDistrict", "SiteMaintenance", new RouteValueDictionary(new { districtID = @Model.DistrictID }))
posted on Monday, November 07, 2011 8:53:15 AM (Central Standard Time, UTC-06:00)  #    Comments [2]
# Monday, October 31, 2011

I recently put together an Entity Framework Code First demo that I presented to my colleagues at Skyline Technologies.

The demo includes:

  • Generating DB from POCO’s
  • Fluent and Attribute EF configuration examples
  • Creating Relationships (1 –> Many, Many –> Many)
  • Seeding Data
  • Using a separate DB instance for integration testing
  • How using Data Annotations saves you time in MVC
  • New Features Coming In EF vNext
    • Enums
    • Spatial Data Type

I put the code up on GitHub so if you are looking for an EF Code First kick starter took a look!

posted on Monday, October 31, 2011 7:35:41 AM (Central Standard Time, UTC-06:00)  #    Comments [3]
# Saturday, October 29, 2011

My latest project was being done in ASP.NET MVC3 and I needed to do some date validation that was beyond what was available out-of-the-box.  I Googled around the inter-webs for awhile and couldn’t find anything that met my needs so I decided to create my own set of extensions…and while I was at create my NuGet package and CodePlex project.

For some reason the validation attributes available for the Date data type are non-existence in MVC.  You can compare to another model field, but that only checks for equality.  You can use regular expressions, which is not fun, and you can only compare against static values, or you can create your own validation attributes…which is the route I chose.

I created custom validation attributes that I found that I needed in my projects and packed some up to make available to the masses.

EzValidation contains validation for:

  • Equal, NotEqual, Greater, Less, GreaterOrEqual, LessOrEqual
    • Available for all Primitive Data Types (including nullable)
    • Compare to another field in the Model
        1. [Equal("Email")]
        2. public string ConfirmEmail { get; set; }
    • Compare to a specific value
        1. [NotEqual("|28|")]
        2. public int Age {get; set;}
    • Compare to Current Date (Dates and Strings only)
        1. [Greater("CompareToCurrentDate")]
        2. public DateTime ADateInTheFuture { get; set; }
    • Compare to Yesterday's Date (Dates and Strings only)
        1. [Less("CompareToYesterday")]
        2. public DateTime DateBeforeYesterday { get; set; }
    • Compare to Tomorrow's Date (Dates and Strings only)
        1. [GreaterOrEqual("CompareToTomorrow")]
        2. public DateTime DateAfterTomorrow { get; set; }


    The source Code is available on CodePlex.

    The package can be installed via NuGet.  “package-install EzValidation"

    posted on Saturday, October 29, 2011 7:09:00 PM (Central Daylight Time, UTC-05:00)  #    Comments [1]
    # Sunday, July 03, 2011

    Earlier this year during Chicago Code Camp 3, I had the privilege of sitting down with Clark Sell and Marc Nichols and recording my first podcast.  Clark and Mark are the duo behind Developer Smackdown.  If you are not familiar with Developer Smackdown I suggest you take a listen.  In my musing, as Clark and Marc refer to the episodes, we discuss a topic very near and dear to my hear, Test-driven Development.  Take a listen and let me know what you think.

     TDD With Keith Burnell

    posted on Sunday, July 03, 2011 8:30:00 PM (Central Daylight Time, UTC-05:00)  #    Comments [2]