Localized ViewEngines using multiple routes - razor

I am trying to make a simple multi-language website. Overriding FindView to get the file based on the language is easy, my problem comes in the routing part.
I would like to do is: (have a website with 2 languages - pt-br and en-us, let abbreviate to onlu pt and en - the default would be PT)
User types www.mysite.com -> would find the languages in the user header request and if the user doesn´t have any of them, he would be redirected to the default PT, so the end result would be www.mysite.com in Portuguese. If he has en, he would be redirected to www.mysite.com/en/ , the result would be the view in English.
If the user types www.mysite.com/pt/ -> I would check that he wants the default and would redirect to www.mysite.com in Portuguese.
I did a custom engine to get the correct view based on the language. But it´s not working 100% because the routing problem.
IN my case I am trying to route with
routes.MapRoute(
"Localization", // Route name
"{lang}/{controller}/{action}", // URL with parameters
new { lang = "pt", controller = "Home", action = "Index" } //defaults
);
But with this, when someone types /pt/ will not redirect to the root of the site.
Another problem with the route is that I don´t want to anyone typing the controller name, I just want the action, my website just have one Home controller with few actions.
Another problem is the that I want a different action name, like, CONTACT in English and CONTATO in Portuguese, they should appear on the address bar like www.mysite.com/Contato or www.mysite.com/en/Contact
Mu Engine I did base on this solution http://www.counity.at/blog/2012/asp-net-mvc3-localization-using-culture-dependent-views/ by Guido Breitenhuber
Here is the code with some tweaks (it´s not working 100% yet)
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc;
using System.Globalization;
namespace Ala.MultiLanguage
{
public class LocalizedViewLocation : RazorViewEngine
{
private static readonly string[] _emptyLocations = new string[0];
public string[] LocalizedViewLocationFormats { get; set; }
public string[] LocalizedMasterLocationFormats { get; set; }
protected string[] LocalizedPartialViewLocationFormats { get; set; }
public LocalizedViewLocation()
{
// Define the localized view locations
// 0: Language
// 1: View name
// 2: Controller name
LocalizedViewLocationFormats = new[] {
"~/Views/{0}/{2}/{1}.cshtml",
"~/Views/Shared/{0}/{1}.cshtml"};
MasterLocationFormats = new[] {
"~/Views/{0}/{2}/{1}.cshtml",
"~/Views/Shared/{0}/{1}.cshtml"};
LocalizedPartialViewLocationFormats = new[] {
"~/Views/{0}/{2}/{1}.cshtml",
"~/Views/Shared/{0}/{1}.cshtml"};
}
public override ViewEngineResult FindPartialView(ControllerContext controllerContext, string partialViewName, bool useCache)
{
if (controllerContext == null)
throw new ArgumentNullException("controllerContext");
if (String.IsNullOrEmpty(partialViewName))
throw new ArgumentException("Parameter partialViewName is null or empty.", "partialViewName");
string[] searched;
var controllerName = controllerContext.RouteData.GetRequiredString("controller");
var partialPath = GetPath(controllerContext, LocalizedPartialViewLocationFormats, partialViewName, controllerName, out searched);
if (String.IsNullOrEmpty(partialPath))
{
var baseRes = base.FindPartialView(controllerContext, partialViewName, useCache);
if (baseRes.View != null)
return baseRes;
return new ViewEngineResult(searched.Union(baseRes.SearchedLocations));
}
return new ViewEngineResult(CreatePartialView(controllerContext, partialPath), this);
}
public override ViewEngineResult FindView(ControllerContext controllerContext, string viewName, string masterName, bool useCache)
{
if (controllerContext == null)
throw new ArgumentNullException("controllerContext");
if (String.IsNullOrEmpty(viewName))
throw new ArgumentException("Parameter viewName is null or empty.", "viewName");
string[] viewLocationsSearched;
string[] masterLocationsSearched;
var controllerName = controllerContext.RouteData.GetRequiredString("controller");
var viewPath = GetPath(controllerContext, LocalizedViewLocationFormats, viewName, controllerName, out viewLocationsSearched);
var masterPath = GetPath(controllerContext, LocalizedMasterLocationFormats, masterName, controllerName, out masterLocationsSearched);
if (String.IsNullOrEmpty(viewPath) || (String.IsNullOrEmpty(masterPath) && !String.IsNullOrEmpty(masterName)))
{
var baseRes = base.FindView(controllerContext, viewName, masterName, useCache);
if (baseRes.View != null)
return baseRes;
return new ViewEngineResult(viewLocationsSearched.Union(masterLocationsSearched).Union(baseRes.SearchedLocations));
}
return new ViewEngineResult(CreateView(controllerContext, viewPath, masterPath), this);
}
private string GetPath(ControllerContext controllerContext, string[] locations, string name, string controllerName, out string[] searchedLocations)
{
searchedLocations = _emptyLocations;
if (String.IsNullOrEmpty(name))
return String.Empty;
if (IsSpecificPath(name))
return String.Empty;
return GetPathFromGeneralName(controllerContext, locations, name, controllerName, ref searchedLocations);
}
private static bool IsSpecificPath(string name)
{
char c = name[0];
return (c == '~' || c == '/');
}
private string GetPathFromGeneralName(ControllerContext controllerContext, string[] locations, string name, string controllerName, ref string[] searchedLocations)
{
var result = String.Empty;
searchedLocations = new string[locations.Length];
for (int i = 0; i < locations.Length; i++)
{
var location = locations[i];
var virtualPath = string.Format(CultureInfo.InvariantCulture, location, CultureInfo.CurrentUICulture.TwoLetterISOLanguageName, name, controllerName);
if (FileExists(controllerContext, virtualPath))
{
searchedLocations = _emptyLocations;
result = virtualPath;
break;
}
searchedLocations[i] = virtualPath;
}
return result;
}
}
}

Well, after some timing trying to do in the best way, I ´ve found one solution much easier and fast to implement.
Just mapped the routes that I want one-by-one in the global.asax. This will work and will be fast to implement if you have only few pages and languages.
routes.IgnoreRoute("{resource}.axd/{*pathInfo}");
routes.MapRoute("Default-BR", "", new { controller = "Home", action = "Index" });
routes.MapRoute("Default-EN", "en", new { controller = "Home", action = "IndexEN" });
routes.MapRoute("HotelBR", "Hotel", new { controller = "Home", action = "Index" });
routes.MapRoute("HotelEN", "en/Hotel", new { controller = "Home", action = "IndexEN" });
routes.MapRoute("Apartamento", "Apartamento", new { controller = "Home", action = "Apartamentos" });
routes.MapRoute("Apartamentos", "Apartamentos", new { controller = "Home", action = "Apartamentos" });
routes.MapRoute("Apartments", "en/Apartments", new { controller = "Home", action = "ApartamentosEN" });
routes.MapRoute("Localizacao", "Localizacao", new { controller = "Home", action = "Localizacao" });
routes.MapRoute("Location", "en/Location", new { controller = "Home", action = "LocalizacaoEN" });
routes.MapRoute("Tarifa", "Tarifa", new { controller = "Home", action = "Tarifas" });
routes.MapRoute("Tarifas", "Tarifas", new { controller = "Home", action = "Tarifas" });
routes.MapRoute("Rates", "en/Rates", new { controller = "Home", action = "TarifasEN" });
routes.MapRoute("Reserva", "Reserva", new { controller = "Home", action = "Reservas" });
routes.MapRoute("Reservas", "Reservas", new { controller = "Home", action = "Reservas" });
routes.MapRoute("Booking", "en/Booking", new { controller = "Home", action = "ReservasEN" });
routes.MapRoute("Contato", "Contato", new { controller = "Home", action = "Contato" });
routes.MapRoute("Contact", "en/Contact", new { controller = "Home", action = "ContatoEN" });

Related

How does Asp.net Core renders a view

How does MVC 6 renders a view. What's the actual method in Razor ViewEngine that generates the html output? Also if possible please explain the process of rendering a view.
May be you could point me to a file on mvc source on github. thanks!
Here is a complete solution of what you are looking for. I used dependency injection to get the HtmlHelper in the controller. You can inject your own helper if you want too.
using Microsoft.AspNet.Html.Abstractions;
using Microsoft.AspNet.Mvc;
using Microsoft.AspNet.Mvc.ModelBinding;
using Microsoft.AspNet.Mvc.Rendering;
using Microsoft.AspNet.Mvc.ViewEngines;
using Microsoft.AspNet.Mvc.ViewFeatures;
using Microsoft.AspNet.Mvc.ViewFeatures.Internal;
using Microsoft.Extensions.WebEncoders;
using System.ComponentModel.DataAnnotations;
using System;
public class MyController : Controller
{
private readonly IHtmlGenerator htmlGenerator;
ICompositeViewEngine viewEngine;
IModelMetadataProvider metadataProvider;
private readonly IHtmlHelper helper;
IHtmlEncoder htmlEncoder;
IUrlEncoder urlEncoder;
IJavaScriptStringEncoder javaScriptStringEncoder;
public MyController(IHtmlHelper helper, IHtmlGenerator htmlGenerator, ICompositeViewEngine viewEngine, IModelMetadataProvider metadataProvider, IHtmlEncoder htmlEncoder, IUrlEncoder urlEncoder, IJavaScriptStringEncoder javaScriptStringEncoder)
{
this.htmlGenerator = htmlGenerator;
this.viewEngine = viewEngine;
this.metadataProvider = metadataProvider;
this.htmlEncoder = htmlEncoder;
this.urlEncoder = urlEncoder;
this.javaScriptStringEncoder = javaScriptStringEncoder;
this.helper = helper;
}
[HttpGet]
public IActionResult MyHtmlGenerator()
{
MyViewModel temp = new MyViewModel();
var options = new HtmlHelperOptions();
options.ClientValidationEnabled = true;
ViewDataDictionary<MyViewModel> dic = new ViewDataDictionary<MyViewModel>(this.metadataProvider, new ModelStateDictionary());
ViewContext cc = new ViewContext(ActionContext, new FakeView(), dic, TempData, TextWriter.Null, options);
var type = typeof(MyViewModel);
var metadata = this.metadataProvider.GetMetadataForType(type);
ModelExplorer modelEx = new ModelExplorer(this.metadataProvider, metadata, temp);
ViewData["Description"] = "test desc";
ViewData["Id"] = 1;
this.ViewData = new ViewDataDictionary(this.metadataProvider, new ModelStateDictionary());
IHtmlHelper<MyViewModel> dd = new HtmlHelper<MyViewModel>(this.htmlGenerator, this.viewEngine, this.metadataProvider, this.htmlEncoder, this.urlEncoder, this.javaScriptStringEncoder);
((ICanHasViewContext)dd).Contextualize(cc);
dd.ViewContext.ViewData = this.ViewData;
var desc = GetString(dd.TextBoxFor(m => m.ID));
var ID = GetString(dd.TextBoxFor(m => m.Description));
// Do whatever you want with the ID and desc
return new ContentResult() { Content = ID + desc };
}
public static string GetString(IHtmlContent content)
{
var writer = new System.IO.StringWriter();
content.WriteTo(writer, new HtmlEncoder());
return writer.ToString();
}
}
public class MyViewModel : BaseAssetViewModel
{
// [RegularExpression(#"^-?\d{1,13}(\.\d{0,5})?$|^-?\.\d{1,5}$")]
[Required]
public int ID { get; set; }
[MinLength(2)]
public string Description { get; set; }
// Property with no validation
public string Other { get; set; }
}
public class FakeView : IView
{
string IView.Path
{
get
{
throw new NotImplementedException();
}
}
public Task RenderAsync(ViewContext viewContext)
{
throw new InvalidOperationException();
}
Task IView.RenderAsync(ViewContext context)
{
throw new NotImplementedException();
}
}
I don't know if this may be of help, may be you have to start to look at tag helpers:
https://github.com/DamianEdwards/TagHelperStarterWeb
they're working to a different way to create helpers that integrate in the page in a more natural way.

Html.ListBoxFor Object reference not set to an instance of an object Error

I am using view model to display a dropdownlist and i am also trying to get the value of the selected list, here is my view model
public class CreateJobViewModel
{
public int[] SelectedIndustriesIds { get; set; }
public IList<SelectListItem> IndustriesList { get; set; }
}
My controller
public ActionResult Create()
{
var industryList = repository.GetAllIndustries();
var model = new CreateJobViewModel
{
IndustriesList = industryList.Select(i => new SelectListItem
{
Value = i.IndustryId.ToString(),
Text = i.Name
}).ToList()
};
return View("~/Views/Dashboard/Job/Create.cshtml", model);
}
My post controller
[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult Create(CreateJobViewModel model)
{
try
{
var job = new Job()
{
Title = "hi",
EmploymentHourId = 1,
LocationId = 1,
Salary = 50,
SalaryPeriodId = 1,
PostCode = 2131,
Role = "world",
Description = "hello",
IsPublished = false,
ShiftId = 1,
WorkDayId = 1,
NumberOfPosition = 5,
Meal = false,
SecondYearVisa = true,
Sponsorship = true,
Accommodation = true,
DurationId = 1,
IndustryExperiencePeriod = 5,
Id = User.Identity.GetUserId(),
};
foreach (int id in model.SelectedIndustriesIds)
{
var industry = repository.Industry(id);
job.Industries.Add(industry);
}
foreach (int id in model.SelectedSpecialRequirementsId)
{
var special = repository.SpecialRequirement(id);
job.SpecialRequirements.Add(special);
}
repository.AddJob(job);
return RedirectToAction("Create");
}
catch
{
return View("~/Views/Dashboard/Job/Create.cshtml");
}
}
Every time i try to submit the selected value, i get Object reference not set to an instance of an object Error on the following line in my view:
#model Taw.WebUI.Models.CreateJobViewModel
#Html.ListBoxFor(m => m.SelectedIndustriesIds, Model.IndustriesList) -- here i get the error
Any reason why?
When you submit the form your throwing an exception (confirmed in the comments) and in the catch block you are returning the view, which throws the exception you are seeing because Model.IndustriesList is null. You need to re-assign the value before you return the view.
Since you need to assign SelectLists in the GET method and in the POST method if you return the view, I tend to re-factor this to a separate method to keep the controller code a bit cleaner. Note the following code is based on your model property being public SelectList IndustriesList { get; set; } which is a bit simpler than building IList<SelectListItem>
private void ConfigureViewModel(CreateJobViewModel model)
{
var industryList = repository.GetAllIndustries();
model.IndustriesList = new SelectList(industryList, "IndustryId", "Name")
// any other common stuff
}
and then in the action methods
public ActionResult Create()
{
var model = new CreateJobViewModel();
ConfigureViewModel(model);
return View(model);
}
public ActionResult Create(CreateJobViewModel model)
{
try
{
....
}
catch
{
ConfigureViewModel(model);
return View(model);
}
}
Note its also good practice to test if the model is valid before attempting to save it
public ActionResult Create(CreateJobViewModel model)
{
if (!ModelState.IsValid)
{
ConfigureViewModel(model);
return View(model); // return the view so the user can correct validation errors
}
....

Removing First Item from listbox while binding to listbox

I have parsed the feed http://www.toucheradio.com/toneradio/android/toriLite/AndroidRSS.xml
And all items from rss feed displayed in listbox.Now I dont want to get first item I have to omit it.How Can I do it.
MainPage.xaml.cs:
namespace tori
{
public partial class MainPage : PhoneApplicationPage
{
// Constructor
public MainPage()
{
InitializeComponent();
// is there network connection available
if (!System.Net.NetworkInformation.NetworkInterface.GetIsNetworkAvailable())
{
MessageBox.Show("No network connection available!");
return;
}
// start loading XML-data
WebClient downloader = new WebClient();
Uri uri = new Uri(" http://www.toucheradio.com/toneradio/android/toriLite/AndroidRSS.xml", UriKind.Absolute);
downloader.DownloadStringCompleted += new DownloadStringCompletedEventHandler(ChannelDownloaded);
downloader.DownloadStringAsync(uri);
}
void ChannelDownloaded(object sender, DownloadStringCompletedEventArgs e)
{
if (e.Result == null || e.Error != null)
{
MessageBox.Show("There was an error downloading the XML-file!");
}
else
{
// Deserialize if download succeeds
XDocument document = XDocument.Parse(e.Result);
var queue = from item in document.Descendants("item")
select new Item
{
title = item.Element("title").Value
,
link = item.Element("link").Value
,
ThumbnailUrl = item.Element(item.GetNamespaceOfPrefix("media") + "thumbnail").Attribute("url").Value
,
};
itemsList.ItemsSource = queue;
}
}
public class Item
{
public string title { get; set; }
public string ThumbnailUrl { get; set; }
public string link { get; set; }
}
If I write queue.RemoveAt(0);
i was getting error at RemoveAt.
Can anybody please tell me how can I do that.
Many Thanks in advance.
You can easily do this using LINQ Skip extension method (documentation here).
Just try the sample below:
itemsList.ItemsSource = queue.Skip(1);
As well you can rewrite the query to omit the first item before applying the projection in the select method using the methods chain approach:
var queue = document.Descendants("item")
.Skip(1)
.Select(item => new Item
{
title = item.Element("title").Value,
link = item.Element("link").Value,
ThumbnailUrl = item.Element(item.GetNamespaceOfPrefix("media") + "thumbnail").Attribute("url").Value,
})
.ToList();
itemsList.ItemsSource = queue;
UPDATE / DUE TO COMMENTS
And as well if you need to skip items at certain indexes you may use the Where method and the HasSet as in the sample below:
var document = XDocument.Parse(e.Result);
var indexes = new HashSet<int> { 1, 3, 4 };
var queue = document.Descendants("item")
.Select(item => new Item
{
title = item.Element("title").Value,
link = item.Element("link").Value,
ThumbnailUrl =
item.Element(item.GetNamespaceOfPrefix("media") + "thumbnail").Attribute("url").Value,
})
.Where((x, i) => !indexes.Contains(i))
.ToList();
Items.ItemsSource = queue;

How can I properly localize Razor Views in ServiceStack

I am currently getting the prefered Culture from the Accept-Language-HTTP-Header and storing it in the AuthUserSession.
In AppHost.Configure:
PreRequestFilters.Add((httpReq, httpResp) =>
{
var session = httpReq.GetSession();
if (session is AuthUserSession)
{
var auths = ((AuthUserSession)session);
if (auths.Culture == null)
{
//parse languages
var languages = httpReq.Headers["Accept-Language"];
//auths.Culture = Helpers.CultureHelper.GetBestAcceptLanguageMatch(languages);
auths.Culture = "en-US";
httpReq.SaveSession(session, new TimeSpan(0, 20, 0));
}
}
});
My current solution to Render a View in the users prefered Culture is to change the current Threads UICulture from the Razor view:
#inherits ViewPage<LandingPage.ServiceModel.Operations.AskQuestions>
#{
var session = GetSession<ServiceStack.ServiceInterface.Auth.AuthUserSession>();
var prevCulture = System.Threading.Thread.CurrentThread.CurrentUICulture;
System.Threading.Thread.CurrentThread.CurrentUICulture = System.Globalization.CultureInfo.GetCultureInfo(session.Culture);
//access a Resource
ViewBag.Title = Resources.AskTitle;
}
Views Content
#{
System.Threading.Thread.CurrentThread.CurrentUICulture = prevCulture;
}
This seems unelegant and clumsy. What would be a better way to do this?
*edit:
I am looking for two hook points: one just before the View gets called, and one right after it got rendered. These should keep the interference with other Requests that get served to zero.
I discovered today that a custom IServiceRunner supplies just the right hooks (see https://github.com/ServiceStack/ServiceStack/wiki/Customize-HTTP-Responses).
As the one above it only works, when the page is served by a Service, because the RequestFilters and the ServiceRunner are not even touched when a ContentPage is requested.
It might be of interest, that the RequestFilter is another hook point, that is called before the Execution of the View. But the same seems true for the ResponseFilter. A small test in which I tried to reset the CurrentUICulture in the ResponseFilter rendered my page unlocalized.
In AppHost
public override void Configure(Funq.Container container)
{
//plugins
Plugins.Add(new RazorFormat());
Plugins.Add(new AuthFeature(() =>
new AuthUserSession(),
new IAuthProvider[] {
new BasicAuthProvider()
}));
//request filters
PreRequestFilters.Add((httpReq, httpResp) =>
{
var session = httpReq.GetSession();
if (session is AuthUserSession)
{
var auths = ((AuthUserSession)session);
if (auths.Culture == null)
{
var languages = httpReq.Headers["Accept-Language"];
auths.Culture = Helpers.CultureHelper.GetBestAcceptLanguageMatch(languages);
httpReq.SaveSession(session, new TimeSpan(0, 20, 0));
}
httpReq.SetItem("Culture", auths.Culture);
}
});
//funq
var userRep = new InMemoryAuthRepository();
container.Register<IUserAuthRepository>(userRep);
container.Register<ICacheClient>(c => new MemoryCacheClient());
}
//use a custom IServiceRunner
public override ServiceStack.ServiceHost.IServiceRunner<TRequest> CreateServiceRunner<TRequest>(ActionContext actionContext)
{
var runner = base.CreateServiceRunner<TRequest>(actionContext);
return new CultureAwareServiceRunner<TRequest>(this, actionContext);
}
CultureAwareServiceRunner.cs
public class CultureAwareServiceRunner<T> : ServiceRunner<T>
{
public CultureAwareServiceRunner(AppHost appHost, ServiceStack.WebHost.Endpoints.ActionContext actionContext) :
base(appHost, actionContext)
{ }
public override void OnBeforeExecute(IRequestContext requestContext, T request)
{
var httpReq = requestContext.Get<IHttpRequest>();
httpReq.SetItem("PreviousCulture", Thread.CurrentThread.CurrentUICulture);
string culture = httpReq.GetItem("Culture") as string;
if (culture != null)
Thread.CurrentThread.CurrentUICulture = CultureInfo.GetCultureInfo(culture);
base.OnBeforeExecute(requestContext, request);
}
public override object OnAfterExecute(IRequestContext requestContext, object response)
{
var httpReq = requestContext.Get<IHttpRequest>();
var prevCulture = httpReq.GetItem("PreviousCultureCulture") as CultureInfo;
if (prevCulture != null)
Thread.CurrentThread.CurrentUICulture = prevCulture;
return base.OnAfterExecute(requestContext, response);
}
}

Binding an Enum to a DropDownList in MVC 4? [duplicate]

This question already has answers here:
How do you create a dropdownlist from an enum in ASP.NET MVC?
(36 answers)
Closed 8 years ago.
I've been finding all over the place that the common way to bind Enums to DropDowns is through helper methods, which seems a bit overbearing for such a seemingly simple task.
What is the best way to bind Enums to DropDownLists in ASP.Net MVC 4?
You can to this:
#Html.DropDownListFor(model => model.Type, Enum.GetNames(typeof(Rewards.Models.PropertyType)).Select(e => new SelectListItem { Text = e }))
I think it is about the only (clean) way, which is a pity, but at least there are a few options out there. I'd recommend having a look at this blog: http://paulthecyclist.com/2013/05/24/enum-dropdown/
Sorry, it's too long to copy here, but the gist is that he created a new HTML helper method for this.
All the source code is available on GitHub.
Enums are supported by the framework since MVC 5.1:
#Html.EnumDropDownListFor(m => m.Palette)
Displayed text can be customized:
public enum Palette
{
[Display(Name = "Black & White")]
BlackAndWhite,
Colour
}
MSDN link: http://www.asp.net/mvc/overview/releases/mvc51-release-notes#Enum
In my Controller:
var feedTypeList = new Dictionary<short, string>();
foreach (var item in Enum.GetValues(typeof(FeedType)))
{
feedTypeList.Add((short)item, Enum.GetName(typeof(FeedType), item));
}
ViewBag.FeedTypeList = new SelectList(feedTypeList, "Key", "Value", feed.FeedType);
In my View:
#Html.DropDownList("FeedType", (SelectList)ViewBag.FeedTypeList)
The solution from PaulTheCyclist is spot on. But I wouldn't use RESX (I'd have to add a new .resx file for each new enum??)
Here is my HtmlHelper Expression:
public static MvcHtmlString EnumDropDownListFor<TModel, TEnum>(this HtmlHelper<TModel> htmlHelper,
Expression<Func<TModel, TEnum>> expression, object attributes = null)
{
//Get metadata from enum
var metadata = ModelMetadata.FromLambdaExpression(expression, htmlHelper.ViewData);
var enumType = GetNonNullableModelType(metadata);
var values = Enum.GetValues(enumType).Cast<TEnum>();
//Convert enumeration items into SelectListItems
var items =
from value in values
select new SelectListItem
{
Text = value.ToDescription(),
Value = value.ToString(),
Selected = value.Equals(metadata.Model)
};
//Check for nullable value types
if (metadata.IsNullableValueType)
{
var emptyItem = new List<SelectListItem>
{
new SelectListItem {Text = string.Empty, Value = string.Empty}
};
items = emptyItem.Concat(items);
}
//Return the regular DropDownlist helper
return htmlHelper.DropDownListFor(expression, items, attributes);
}
Here is how I declare my enums:
[Flags]
public enum LoanApplicationType
{
[Description("Undefined")]
Undefined = 0,
[Description("Personal Loan")]
PersonalLoan = 1,
[Description("Mortgage Loan")]
MortgageLoan = 2,
[Description("Vehicle Loan")]
VehicleLoan = 4,
[Description("Small Business")]
SmallBusiness = 8,
}
And here is the call from a Razor View:
<div class="control-group span2">
<div class="controls">
#Html.EnumDropDownListFor(m => m.LoanType, new { #class = "span2" })
</div>
</div>
Where #Model.LoanType is an model property of the LoanApplicationType type
UPDATE: Sorry, forgot to include code for the helper function ToDescription()
/// <summary>
/// Returns Description Attribute information for an Enum value
/// </summary>
/// <param name="value"></param>
/// <returns></returns>
public static string ToDescription(this Enum value)
{
if (value == null)
{
return string.Empty;
}
var attributes = (DescriptionAttribute[]) value.GetType().GetField(
Convert.ToString(value)).GetCustomAttributes(typeof (DescriptionAttribute), false);
return attributes.Length > 0 ? attributes[0].Description : Convert.ToString(value);
}
Technically, you don't need a helper method, since Html.DropdownListFor only requires a SelectList or Ienumerable<SelectListItem>. You can just turn your enums into such an output and feed it in that way.
I use a static library method to convert enums into List<SelectListItem> with a few params/options:
public static List<SelectListItem> GetEnumsByType<T>(bool useFriendlyName = false, List<T> exclude = null,
List<T> eachSelected = null, bool useIntValue = true) where T : struct, IConvertible
{
var enumList = from enumItem in EnumUtil.GetEnumValuesFor<T>()
where (exclude == null || !exclude.Contains(enumItem))
select enumItem;
var list = new List<SelectListItem>();
foreach (var item in enumList)
{
var selItem = new SelectListItem();
selItem.Text = (useFriendlyName) ? item.ToFriendlyString() : item.ToString();
selItem.Value = (useIntValue) ? item.To<int>().ToString() : item.ToString();
if (eachSelected != null && eachSelected.Contains(item))
selItem.Selected = true;
list.Add(selItem);
}
return list;
}
public static class EnumUtil
{
public static IEnumerable<T> GetEnumValuesFor<T>()
{
return Enum.GetValues(typeof(T)).Cast<T>();
}
// other stuff in here too...
}
/// <summary>
/// Turns Camelcase or underscore separated phrases into properly spaces phrases
/// "DogWithMustard".ToFriendlyString() == "Dog With Mustard"
/// </summary>
public static string ToFriendlyString(this object o)
{
var s = o.ToString();
s = s.Replace("__", " / ").Replace("_", " ");
char[] origArray = s.ToCharArray();
List<char> newCharList = new List<char>();
for (int i = 0; i < origArray.Count(); i++)
{
if (origArray[i].ToString() == origArray[i].ToString().ToUpper())
{
newCharList.Add(' ');
}
newCharList.Add(origArray[i]);
}
s = new string(newCharList.ToArray()).TrimStart();
return s;
}
Your ViewModel can pass in the options you want. Here's a fairly complex one:
public IEnumerable<SelectListItem> PaymentMethodChoices
{
get
{
var exclusions = new List<Membership.Payment.PaymentMethod> { Membership.Payment.PaymentMethod.Unknown, Membership.Payment.PaymentMethod.Reversal };
var selected = new List<Membership.Payment.PaymentMethod> { this.SelectedPaymentMethod };
return GetEnumsByType<Membership.Payment.PaymentMethod>(useFriendlyName: true, exclude: exclusions, eachSelected: selected);
}
}
So you wire your View's DropDownList against that IEnumerable<SelectListItem> property.
Extending the html helper to do it works well, but if you'd like to be able to change the text of the drop down values based on DisplayAttribute mappings, then you would need to modify it similar to this,
(Do this pre MVC 5.1, it's included in 5.1+)
public static IHtmlString EnumDropDownListFor<TModel, TEnum>(this HtmlHelper<TModel> html, Expression<Func<TModel, TEnum>> expression)
{
var metadata = ModelMetadata.FromLambdaExpression(expression, html.ViewData);
var enumType = Nullable.GetUnderlyingType(metadata.ModelType) ?? metadata.ModelType;
var enumValues = Enum.GetValues(enumType).Cast<object>();
var items = enumValues.Select(item =>
{
var type = item.GetType();
var member = type.GetMember(item.ToString());
var attribute = member[0].GetCustomAttribute<DisplayAttribute>();
string text = attribute != null ? ((DisplayAttribute)attribute).Name : item.ToString();
string value = ((int)item).ToString();
bool selected = item.Equals(metadata.Model);
return new SelectListItem
{
Text = text,
Value = value,
Selected = selected
};
});
return html.DropDownListFor(expression, items, string.Empty, null);
}