Question

我已将Jeremiah Clark的CheckBoxList Helper for MVC翻译成我的VB.Net项目，但当我尝试在我的视图中使用该方法时，我收到了错误

'CheckBoxList' is not a member of 'System.Web.Mvc.HtmlHelper(Of Attenda.Stargate.Web.UserRolesViewModel)'.

谁能告诉我哪里出错了？

助手模块：

Imports System.Runtime.CompilerServices

Public Module InputExtensions

  <Extension()> _
  Public Function CheckBoxList(ByVal htmlHelper As HtmlHelper, ByVal name As String, ByVal listInfo As List(Of ListItem)) As String
    Return htmlHelper.CheckBoxList(name, listInfo, DirectCast(Nothing, IDictionary(Of String, Object)))
  End Function

  <Extension()> _
  Public Function CheckBoxList(ByVal htmlHelper As HtmlHelper, ByVal name As String, ByVal listInfo As List(Of ListItem), ByVal htmlAttributes As Object) As String
    Return htmlHelper.CheckBoxList(name, listInfo, DirectCast(New RouteValueDictionary(htmlAttributes), IDictionary(Of String, Object)))
  End Function

  <Extension()> _
  Public Function CheckBoxList(ByVal htmlHelper As HtmlHelper, ByVal name As String, ByVal listInfo As List(Of ListItem), ByVal htmlAttributes As IDictionary(Of String, Object)) As String
    If String.IsNullOrEmpty(name) Then
      Throw New ArgumentException("The argument must have a value", "name")
    End If
    If listInfo Is Nothing Then
      Throw New ArgumentNullException("listInfo")
    End If
    If listInfo.Count < 1 Then
      Throw New ArgumentException("The list must contain at least one value", "listInfo")
    End If
    Dim sb As New StringBuilder()
    For Each info As ListItem In listInfo
      Dim builder As New TagBuilder("input")
      If info.Selected Then
        builder.MergeAttribute("checked", "checked")
      End If
      builder.MergeAttributes(Of String, Object)(htmlAttributes)
      builder.MergeAttribute("type", "checkbox")
      builder.MergeAttribute("value", info.Value)
      builder.MergeAttribute("name", name)
      builder.InnerHtml = info.Text
      sb.Append(builder.ToString(TagRenderMode.Normal))
      sb.Append("<br />")
    Next
    Return sb.ToString()
  End Function

End Module

查看来源：

<%@ Page Title="" Language="VB" MasterPageFile="~/Views/Shared/TwoColumn.Master" Inherits="System.Web.Mvc.ViewPage(Of Attenda.Stargate.Web.UserRolesViewModel)" %>

<asp:Content ID="Content1" ContentPlaceHolderID="TitleContent" runat="server">
  Edit User Roles
</asp:Content>
<asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="server">
  <h2>Edit Roles for
    <%=Html.Encode(Model.User.UserName)%></h2>
    <div>
    <%=Html.CheckBoxList("Roles", Model.Roles)%>
    </div>
</asp:Content>
<asp:Content ID="Content3" ContentPlaceHolderID="cphLeftPanel" runat="server">
</asp:Content>

Answer 1

您需要将包含自定义帮助程序类的命名空间导入到视图页面中。您可以在页面本身或所有页面的web.config文件中执行此操作。首先将代码放入命名空间。

<%@ Import Namespace="MyProject.Extensions" %>

或（在web.config中）

<pages>
   ...
   <namespaces>
       ...
       <add namespace="MyProject.Extensions" />
   </namespaces>
</pages>

Answer 2

我遇到了这个问题，因为我没有宣布模块是公开的。

这个问题还问了here

自定义HtmlHelper扩展方法在View中不可用？

2 个答案: