PostBack twice for a button click?

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  • pedestrian via DotNetMonster.com
    #1

    PostBack twice for a button click?

    I have a simple VB ASP.NET 2.0 page with a Button and a Label.
    The Label text is "0". For each click of the button (btnAdd), it should
    increment the Label text by 1.

    The code:

    Protected Sub btnAdd_Click(.. .) Handles btnAdd.Click
    Trace.Warn("Bef ore add: " & lblCounter.Text )
    lblCounter.Text = (Int32.Parse(lb lCounter.Text) + 1).ToString
    Trace.Warn("Aft er add: " & lblCounter.Text )
    End Sub

    However, each time I click the button, the label always increase
    by 2 instead of the expected 1. What's the problem area?

    I tried to debug using Trace.
    I get the following result from the trace:

    Begin Raise PostBackEvent
    Before add: 0
    After add: 1
    Before add: 1
    After add: 2
    End Raise PostBackEvent

    Is this signifies PostBack event is being run twice per button click?
    How to solve it?

    Thanks for your assistance.

    --
    Regards,
    Pedestrian, Penang.

    Message posted via http://www.dotnetmonster.com

    Tags: None
    • Steven Nagy
      #2
      Re: PostBack twice for a button click?

      Hi can you post all code except for designer generated code?
      There's no way that the method should be executing twice.

        Comment

        • pedestrian via DotNetMonster.com
          #3
          Re: PostBack twice for a button click?

          (Default.aspx)
          <%@ Page Language="VB" AutoEventWireup ="true" CodeFile="Defau lt.aspx.vb"
          Inherits="_Defa ult" Trace="true"%>
          <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "
          http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dt d">
          <html xmlns="http://www.w3.org/1999/xhtml" >
          <head runat="server">
          <title>Untitl ed Page</title>
          </head>
          <body>
          <form id="form1" runat="server">
          <div>
          <asp:Button ID="btnAdd" Text="Add" OnClick="btnAdd _Click"
          runat="server" />
          <asp:Label ID="lblCounter " Text="0" runat="server" />
          </div>
          </form>
          </body>
          </html>

          (Default.aspx.v b)
          Partial Class _Default
          Inherits System.Web.UI.P age

          Protected Sub btnAdd_Click(By Val sender As Object, ByVal e As System.
          EventArgs) Handles btnAdd.Click
          Trace.Warn("Bef ore add: " & lblCounter.Text )
          lblCounter.Text = (Int32.Parse(lb lCounter.Text) + 1).ToString
          Trace.Warn("Aft er add: " & lblCounter.Text )
          End Sub
          End Class

          --
          Regards,
          Pedestrian, Penang.

          Message posted via http://www.dotnetmonster.com

            Comment

            • jjoy
              #4
              Re: PostBack twice for a button click?

              Sounds like you might have an event handler in the designer file in
              addition to the specification in the label tag.

                Comment

                • pedestrian via DotNetMonster.com
                  #5
                  Re: PostBack twice for a button click?

                  Thanks. I shall check it up.

                  --
                  Regards,
                  Pedestrian, Penang.

                  Message posted via DotNetMonster.c om
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                    Comment

                    • Damien
                      #6
                      Re: PostBack twice for a button click?

                      pedestrian via DotNetMonster.c om wrote:
                      (Default.aspx)
                      <%@ Page Language="VB" AutoEventWireup ="true" CodeFile="Defau lt.aspx.vb"
                      Inherits="_Defa ult" Trace="true"%>
                      <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "
                      http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dt d">
                      <html xmlns="http://www.w3.org/1999/xhtml" >
                      <head runat="server">
                      <title>Untitl ed Page</title>
                      </head>
                      <body>
                      <form id="form1" runat="server">
                      <div>
                      <asp:Button ID="btnAdd" Text="Add" OnClick="btnAdd _Click"
                      runat="server" />
                      <asp:Label ID="lblCounter " Text="0" runat="server" />
                      </div>
                      </form>
                      </body>
                      </html>
                      >
                      (Default.aspx.v b)
                      Partial Class _Default
                      Inherits System.Web.UI.P age
                      >
                      Protected Sub btnAdd_Click(By Val sender As Object, ByVal e As System.
                      EventArgs) Handles btnAdd.Click
                      Trace.Warn("Bef ore add: " & lblCounter.Text )
                      lblCounter.Text = (Int32.Parse(lb lCounter.Text) + 1).ToString
                      Trace.Warn("Aft er add: " & lblCounter.Text )
                      End Sub
                      End Class
                      >
                      --
                      Regards,
                      Pedestrian, Penang.
                      AutoEventWireup ="true" - Find all of the <control name>_<event name>
                      methods add attach them to the <control name>.<event nameevent

                      Handles <control name>.<event name- Attach this method to the
                      <control name>.<event nameevent.

                      So your btnAdd_Click method is being attached to the btnAdd.Click event
                      twice, and is hence being called twice. My normal advice would be to
                      set AutoEventWireup to false.

                      Damien

                        Comment

                        • pedestrian via DotNetMonster.com
                          #7
                          Re: PostBack twice for a button click?

                          Thanks for valuable answer, Damien.

                          Damien wrote:
                          >(Default.asp x)
                          ><%@ Page Language="VB" AutoEventWireup ="true" CodeFile="Defau lt.aspx.vb"
                          >[quoted text clipped - 31 lines]
                          >Regards,
                          >Pedestrian, Penang.
                          >
                          >AutoEventWireu p="true" - Find all of the <control name>_<event name>
                          >methods add attach them to the <control name>.<event nameevent
                          >
                          >Handles <control name>.<event name- Attach this method to the
                          ><control name>.<event nameevent.
                          >
                          >So your btnAdd_Click method is being attached to the btnAdd.Click event
                          >twice, and is hence being called twice. My normal advice would be to
                          >set AutoEventWireup to false.
                          >
                          >Damien
                          --
                          Regards,
                          Pedestrian, Penang.

                          Message posted via DotNetMonster.c om
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                          http://www.dotnetmonster.com/Uwe/Forums.aspx/asp-net/200610/1
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                            Comment

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