如何从一个嵌套页面内访问一个顶层母版页子？ [英] How to access a top level master page sub from within a nested page?

问题描述

母版页结构

 顶尖高手
    PAGE MASTERTopMaster.ErrorMsg（ERRMSG）在这里不引发错误
        PAGETopMaster.ErrorMsg（ERRMSG）这里抛出错误
 

我无法获得从基本页面访问顶层类。

顶尖高手ASPX

 ＆LT; ASP：文字ID =litMsg=服务器/＆GT;
 

PAGE.VB

 部分公共类的BasePage
  继承System.Web.UI.Page  公共小组的Page_Load（BYVAL发件人为对象，BYVAL E上EventArgs的）把手Me.Load
    TopMaster.ErrorMsg（ERRMSG）
    错误BC30451：TopMaster不宣布它可能无法访问由于其保护级别。
  结束小组末级
 

MASTER.VB

 部分公共类PageMaster
  继承System.Web.UI.MasterPage末级
 

TOP MASTER.VB

 部分公共类TopMaster
  继承System.Web.UI.MasterPage  公共共享子ERRORMSG（ERRMSG作为字符串）
    昏暗的MYPAGE = TryCast（HttpContext.Current.Handler，页）    如果我的空间状态并没有任何再
      点心师傅= myPage.Master
      昏暗myMaster = TryCast（master.Master，TopMaster）
      虽然master.Master IsNot运算没有AndAlso运算myMaster是Nothing
        主= master.Master
        myMaster = TryCast（主，TopMaster）
      虽然结束      myMaster.litMsg.Text = ERRMSG
    万一  结束小组末级
 

解决方案

更新：现在很明显，使课堂公开，否则你不能访问它：

 部分公共类TopMaster
 

<击>你应该向我们展示包括堆栈跟踪确切的错误信息。看来，键入顶尖高手没有声明这是没有意义的，因为你是在类 TopMaster 。

所以我怀疑，继修复你的核心问题。错误：顶尖高手没有声明，但它可能是有用的反正

如果您要访问的文字，你应该提供一个属性的 TopMaster 是这样的：

 公共财产ERRORMSG作为字符串
    得到
        返回Me.litMsg.Text
    到底得的
    设置（值作为字符串）
        Me.litMsg.Text =价值
    结束设定
高端物业
 

在这种方式，如果你想没有打破code，你甚至可以改变控制型。它的好得多，而不是暴露控件本身。

我猜你也必须分配从循环内移到外面。您还应该使用昏暗myMaster = TryCast（主，TopMaster）一开始，而不是因为你与 TryCast做直接跳转到页面的主的主人（ master.Master，TopMaster）：

 公共共享子ERRORMSG（ERRMSG作为字符串）
    昏暗的MYPAGE = TryCast（HttpContext.Current.Handler，页）    如果我的空间状态并没有任何再
        点心师傅= myPage.Master
        昏暗myMaster = TryCast（主，TopMaster）
        虽然master.Master IsNot运算没有AndAlso运算myMaster是Nothing
            主= master.Master
            myMaster = TryCast（主，TopMaster）
        虽然结束
        myMaster.ErrorMsg = ERRMSG
    万一结束小组
 

否则，你只能分配 ERRORMSG 如果主是页面的硕士硕士硕士，或者它更深刻嵌套。

MASTER PAGE STRUCTURE

TOP MASTER
    PAGE MASTER "TopMaster.ErrorMsg(ErrMsg) Here throws NO error"
        PAGE "TopMaster.ErrorMsg(ErrMsg) Here throws error"

I am unable to gain access to the top level class from the base page.

TOP MASTER ASPX

<asp:Literal ID="litMsg" runat="Server"/>

PAGE.VB

Partial Public Class BasePage
  Inherits System.Web.UI.Page

  Public Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load
    TopMaster.ErrorMsg(ErrMsg) 
    "Error BC30451: TopMaster is not declared it may be inaccessible due to its protection level."
  End Sub

End Class

MASTER.VB

Partial Public Class PageMaster
  Inherits System.Web.UI.MasterPage

End Class

TOP MASTER.VB

Partial Public Class TopMaster
  Inherits System.Web.UI.MasterPage

  Public Shared Sub ErrorMsg(ErrMsg As String)
    Dim myPage = TryCast(HttpContext.Current.Handler, Page)

    If myPage IsNot Nothing Then
      Dim master = myPage.Master
      Dim myMaster = TryCast(master.Master, TopMaster)
      While master.Master IsNot Nothing AndAlso myMaster Is Nothing
        master = master.Master
        myMaster = TryCast(master, TopMaster)
      End While

      myMaster.litMsg.Text = ErrMsg
    End If

  End Sub

End Class

解决方案

Update: now it's clear, make the class Public, otherwise you can't access it:

Partial Public Class TopMaster

You should show us the exact error message including stacktrace. It seems that the type Top Master is not declared which makes no sense since you are in the class TopMaster.

So i doubt that following fixes your core issue "Error: Top Master is not declared" but it might be useful anyway.

If you want to access that literal you should provide a property in your TopMaster like this:

Public Property ErrorMsg As String
    Get
        Return Me.litMsg.Text
    End Get
    Set(value As String)
        Me.litMsg.Text = value
    End Set
End Property

On this way you can even change the control-type if you want without breaking the code. Its much better than to expose the control itself.

I guess you also have to move the assignment from inside the loop to outside. You should also use Dim myMaster = TryCast(master, TopMaster) at the beginning instead of jumping directly to the page's master's master as you do with TryCast(master.Master, TopMaster):

Public Shared Sub ErrorMsg(ErrMsg As String)
    Dim myPage = TryCast(HttpContext.Current.Handler, Page)

    If myPage IsNot Nothing Then
        Dim master = myPage.Master
        Dim myMaster = TryCast(master, TopMaster)
        While master.Master IsNot Nothing AndAlso myMaster Is Nothing
            master = master.Master
            myMaster = TryCast(master, TopMaster)
        End While
        myMaster.ErrorMsg = ErrMsg
    End If

End Sub

Otherwise you are only assigning the ErrorMsg if the master is the page's master's master's master or it's even more deeply nested.

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