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multiple link buttons in one handler error

Question

User1717218719 posted

I have the following code which has an error "Unable to cast object of type 'System.EventArgs' to type 'System.Web.UI.WebControls.CommandEventArgs'"

I am unsure as to why this is happening, any help would be great.

Many Thanks

  Public Sub lnkbttnApproved_Click(sender As Object, e As CommandEventArgs) Handles lnkbttnApproved.Click, lnkbttnPropsed.Click, lnkbttnAmend.Click, lnkbttnCancel.Click '---add all buttons

        Dim lnk As LinkButton = CType(sender, LinkButton)


        Select Case lnk.CommandName

            Case "Approved"
                Call test(1)

            Case "Proposed"
                Call test(2)

            Case "Amend"
                Call test(3)
            Case "Cancel"
                Call test(4)
        End Select

    End Sub

Friday, October 4, 2019 11:05 AM

Answers

User-719153870 posted

Hi E.RU,

According to the code you provided, you are trying to add an OnCommand event rather than a click event for a linkbutton.

If so, please refer to Link Button. On Command(CommandEventArgs) Method for more information and Unable to cast object of type 'System.EventArgs' to type 'System.Web.UI.WebControls.CommandEventArgs' for your similar situation.

For vb version, please also refer to below demo:

ASPX:

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>
</head>
<body>
    <form id="form1" runat="server">
        <div>
            <asp:LinkButton ID="lnkbttnApproved"  OnCommand="lnkbttnApproved_Command" CommandArgument="1" CommandName="Approved" runat="server">LinkButton</asp:LinkButton>
            <asp:LinkButton ID="lnkbttnPropsed" OnCommand="lnkbttnApproved_Command" CommandArgument="1" CommandName="Proposed" runat="server">LinkButton</asp:LinkButton>
            <asp:LinkButton ID="lnkbttnAmend" OnCommand="lnkbttnApproved_Command" CommandArgument="1" CommandName="Amend" runat="server">LinkButton</asp:LinkButton>
            <asp:LinkButton ID="lnkbttnCancel" OnCommand="lnkbttnApproved_Command" CommandArgument="1" CommandName="Cancel" runat="server">LinkButton</asp:LinkButton>
        </div>
    </form>
</body>
</html>

.vb:

Private Sub test(ByVal i As Integer)
        Response.Write(i.ToString())
    End Sub

    Protected Sub lnkbttnApproved_Command(sender As Object, e As CommandEventArgs)
        Select Case e.CommandName

            Case "Approved"
                Call test(1)

            Case "Proposed"
                Call test(2)

            Case "Amend"
                Call test(3)
            Case "Cancel"
                Call test(4)
        End Select
    End Sub

Here's the result of this demo:

Hope this could help.

Best Regard,

Yang Shen

Marked as answer by Anonymous Thursday, October 7, 2021 12:00 AM

Monday, October 7, 2019 2:31 AM

All replies

User409696431 posted

For commands, you want onCommand, not onClick.

e.g:

<asp:LinkButton id="LinkButton1"  
           Text="Order Item 10001" 
           CommandName="Approved"  
           CommandArgument="xxx"  
           OnCommand="LinkButton_Command"  
           runat="server"/>

and code behind (C# - use your VB.net version)

void LinkButton_Command(Object sender, CommandEventArgs e)  
{ 
   //test for e.CommandName and e.CommandArgument values (if you use any) and add your logic
}

Sunday, October 6, 2019 8:24 PM