"Handles Clause Requires A WithEvents..." RSS

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  JDMartin

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  "Handles Clause Requires A WithEvents..."

  Apr 17, 2009 02:48 PM|LINK

  I am using Visual Studio 2008 to build a webpage with nested Master Pages.  My hierarchy is thus:  BGMaster.master ->FunctionMaster.master -> PowerDisplay.aspx.

   I have dropped a Menu object (System.Web.UI.WebControls.Menu) onto my FunctionMaster.master, inside of a Content control.  The object itself causes no problems, but when I create an Event Handler on the FunctionMaster.master.vb page for clicking on the menu:

  Public Sub mnuMenu_MenuItemClick(ByVal sender As Object, ByVal e As MenuEventArgs) Handles mnuMenu.MenuItemClick

  Dim selected As String = ""

  Dim mnuMenu As Menu = DirectCast(Me.FindControl("mnuMenu"), Menu)

  Dim selectedItem As MenuItem = mnuMenu.SelectedItem

  selected = mnuMenu.SelectedItem.Text

  MsgBox(selected)

  End Sub

  the function automatically creates the error:

  "Handles clause requires a WithEvents variable defined in the containing type or one of its base types". 

   I have discovered the following:

  If I comment out the 'Handles mnuMenu.MenuItemClick' clause and add a declaration:  'Protected WithEvents mnuMenu as System.Web.UI.WebControls.Menu' at the top, the error goes away...  but of course this means any attempt to access the Menu object inside the function returns a Null pointer...  because the function isn't accessing the real Menu object...  but an empty variable I declared at the top of the form.

  If I create the Menu object on the BGMaster, the same thing happens.  If I drop it on the PowerDisplay, a regular aspx page, this does not occur.

  If I attempt to declare the WithEvents handler anywhere else, I get an error that says it's already been declared.

  What must I do to be able to handle events in my FunctionMaster.master.vb page for objects declared on my FunctionMaster.master page?

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  anas

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  Re: "Handles Clause Requires A WithEvents..."

  Apr 17, 2009 03:37 PM|LINK

   This may happen if you are placing the menu control inside another control on the masterpage ,

  Please remove the handles clause and instead , assing the event handler declaratively ,

   <asp:Menu ID="mnuMenu" runat="server" OnMenuItemClick="mnuMenu_MenuItemClick">
  

  Anas Ghanem
  • Marked as answer by Hong-Gang Chen - MSFT on Apr 23, 2009 10:14 AM
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  JDMartin

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  Re: "Handles Clause Requires A WithEvents..."

  Apr 17, 2009 04:04 PM|LINK

  Thank you, but I should have mentioned I already tried that.

  The end result is that, at runtime, the line:

  Dim selectedItem As MenuItem = mnuMenu.SelectedItem

  causes a crash, because when it fires, the mnuMenu item is a null pointer. 

  Any other ideas appreciated, however.

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  novicehere

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  Re: "Handles Clause Requires A WithEvents..."

  Apr 17, 2009 05:20 PM|LINK

  Hello There,

  need to ask you something, why are you trying to find the menu control on FunctionMaster. If i am not mistaken the menu is already on the Function Master Page

  JDMartin

  I have dropped a Menu object (System.Web.UI.WebControls.Menu) onto my FunctionMaster.master, inside of a Content control.  The object itself causes no problems, but when I create an Event Handler on the FunctionMaster.master.vb page for clicking on the menu:

  and yes i did get the same error has you have mentioned about the protected with menuitems. But when i tried it with directly adding like

  OnMenuItemClick="MainMenu_MenuItemClick"

  in ChildMaster Page, ( as Mr.Anas suggested) it worked fine. here take a look this

  <%@ Master Language="C#" MasterPageFile="~/MasterPages/parent.master" AutoEventWireup="true" CodeFile="Child2.master.cs" Inherits="NestedMasterPages_Child2" %>

  <asp:Content ID="Content1" ContentPlaceHolderID="head" Runat="Server">

  </asp:Content>

  <asp:Content ID="Content2" ContentPlaceHolderID="cpParent" Runat="Server">

  <div>

  <asp:Menu ID="MainMenu" runat="server" StaticDisplayLevels="2"

  Orientation="Horizontal"

  StaticEnableDefaultPopOutImage="false"

  DynamicEnableDefaultPopOutImage="false"

  OnMenuItemClick="MainMenu_MenuItemClick" >

  <Items>

  <asp:MenuItem Text="Home" Value="Home" >

  <asp:MenuItem Text="MenuItem1" Value="mt1"></asp:MenuItem>

  <asp:MenuItem Text="MenuItem2" Value="mt2"></asp:MenuItem>

  </asp:MenuItem>

  </Items>

  </asp:Menu>

   

  <asp:Label ID="Label1" runat="server"></asp:Label>

  </div>

  </asp:Content>

  and code behind :

  protected void MainMenu_MenuItemClick(object sender, MenuEventArgs e)
      {
          Label1.Text = MainMenu.SelectedItem.Text;
      }

   I had no problems using this in the content page. I do agree the above code is in C#, i hope you can convert it.

  Hope this helps.

  Thanks

   

   

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  • Marked as answer by Hong-Gang Chen - MSFT on Apr 23, 2009 10:13 AM
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  JDMartin

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  6 Posts

  Re: "Handles Clause Requires A WithEvents..."

  Apr 17, 2009 07:23 PM|LINK

  The reason why I am trying to find the Menu object in the VB code is because I cannot access it directly, as your example does.  If I remove the code to get at the mnuMenu object, it produces the following error:

   "Name 'mnuMenu' is not declared."

  For some reason, inside my vb code, I cannot access the mnuMenu object, even though I'm calling it from inside a function of the mnuMenu object, and I'm definitely in the vb page that corresponds to the aspx page.  

   I cannot imagine why your code does not produce the same error mine does.  The language shouldn't make the difference.

   Does this help clarify matters?

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  Hong-Gang Ch...

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  Re: "Handles Clause Requires A WithEvents..."

  Apr 22, 2009 02:11 AM|LINK

  Got it.

  Please check this thread, this thread show you how to access a controls which in the nested master page,

  http://forums.asp.net/t/1270231.aspx

  and please use this tool online to convert C# to VB if you are not familiar with C#,

  http://www.developerfusion.com/tools/convert/csharp-to-vb/

   

  Please mark the replies as answers if they help or unmark if not.
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  • Marked as answer by Hong-Gang Chen - MSFT on Apr 23, 2009 10:13 AM
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  Fadao1

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  8 Posts

  Re: "Handles Clause Requires A WithEvents..."

  Aug 01, 2012 08:14 AM|LINK

  I

  I had the same problen and I had to declare the button using WithEvents.

  Protected WithEvents LinkButtonSearch As LinkButton

  Protected Sub LinkButtonSearch_Click(ByVal sender As Object, ByVal e As EventArgs) Handles LinkButtonSearch.Click

  End Sub

  Felix (Fadao)
  Angola