Html extension in VB.NET MVC 3 application

Question

I implemented a Module using VB.NET in order to handle localization in an MVC .NET application.

However, when I try to call the extension method LanguageSelectorLink from my view, it`s required to provide something for the first parameter of type HtmlHelper. In all C# samples I found on the Internet, this parameter is never provided and it seems to work fine.

@App_Code.LanguageSelectorLink(Nothing, "en-CA", "[English]", "English", Nothing)

Did I miss a step? Can anybody help me?

Imports System.Threading

Namespace App_Code

Public Module SwitchLanguageHelper
    <System.Runtime.CompilerServices.Extension()>
    Public Function LanguageUrl(ByVal helper As HtmlHelper,
                                       ByVal cultureName As String,
                                       Optional ByVal languageRouteName As String = "lang",
                                       Optional ByVal strictSelected As Boolean = False) As Language
        'Set the input language to lower
        cultureName = cultureName.ToLower()

        'retrieve the route values from the view context
        Dim routeValues = New RouteValueDictionary(helper.ViewContext.RouteData.Values)

        'copy the query strings into the route values to generate the link
        Dim queryString = helper.ViewContext.HttpContext.Request.QueryString

        For Each key In queryString
            If (Not (IsNothing(queryString(key))) And
               Not (String.IsNullOrWhiteSpace(queryString(key)))) Then
                If (routeValues.ContainsKey(key)) Then
                    routeValues(key) = queryString(key)
                Else
                    routeValues.Add(key, queryString(key))
                End If

            End If
        Next

        Dim actionName = routeValues("action").ToString()
        Dim controllerName = routeValues("controller").ToString()

        'set the language into route values
        routeValues(languageRouteName) = cultureName

        'generate the language specify url
        Dim urlHelper = New UrlHelper(helper.ViewContext.RequestContext, helper.RouteCollection)
        Dim url = urlHelper.RouteUrl("Localization", routeValues)

        'check whether the current thread ui culture is this language
        Dim current_lang_name = Thread.CurrentThread.CurrentUICulture.Name.ToLower()
        Dim isSelected As Boolean

        If (strictSelected) Then
            current_lang_name = cultureName
        Else
            current_lang_name.StartsWith(cultureName)
        End If

        isSelected = current_lang_name

        Dim language As Language = New Language()

        language.Url = url
        language.ActionName = actionName
        language.ControllerName = controllerName
        language.RouteValues = routeValues
        language.IsSelected = isSelected

        Return language
    End Function

    <System.Runtime.CompilerServices.Extension()>
    Public Function LanguageSelectorLink(ByVal helper As HtmlHelper, ByVal cultureName As String, ByVal selectedText As String, ByVal unselectedText As String, ByVal htmlAttributes As IDictionary(Of String, Object), Optional ByVal languageRouteName As String = "lang", _
                                         Optional ByVal strictSelected As Boolean = False) As MvcHtmlString
        Dim language = helper.LanguageUrl(cultureName, languageRouteName, strictSelected)
        Dim link = helper.RouteLink(If(language.IsSelected, selectedText, unselectedText), "Localization", language.RouteValues, htmlAttributes)

        Return link
    End Function


End Module

End Namespace

aligray aligray · Accepted Answer · 2011-06-19T02:42:17

What you've done is add two extension methods to the HtmlHelper class. The ByVal helper as HtmlHelper is passed implicitly as an instance of the HtmlHelper class when you use these methods.

This is how you use them in a view:

@Imports YourApplicationName.AppCode

@Html.LanguageSelectorLink("en-CA", "[English]", "English", Nothing)

Hope this helps.

Html extension in VB.NET MVC 3 application

1 Answers