为什么在ASP.NET中使用AJAX后我的按钮代码不起作用？

Question

I have a button in asp.net to clear textboxes and I used ajax as below:

<asp:ScriptManager ID="ScriptManager1" runat="server">
</asp:ScriptManager>
<asp:UpdatePanel ID="UpdatePanel1" runat="server">
<ContentTemplate>
<asp:Button ID="Button2" runat="server" Font-Bold="False" Font-Names="Tahoma" Font-Size="16px" ForeColor="DarkRed" Height="40px" OnClick="Button2_Click" Text="Clear Form" Width="165px" />
</ContentTemplate>
</asp:UpdatePanel>

As well, this button has following C# code:

protected void Button2_Click(object sender, EventArgs e)
    {
        txtFirstName.Text = string.Empty;
        txtLastName.Text = string.Empty;
        txtEmail.Text = string.Empty;
        txtSubject.Text = string.Empty;
        txtMessage.Text = string.Empty;
    }

However, foregoing C# code doesn't work when I execute this program!; In other words, textboxes don't clear after I click on button! Please tell me why it happens?!

Answer 1

You need to modify your updatepanel.Kindly place all your Label and TextBox Control inside Update Panel and Button Events outside your UpdatePanel and add Trigger of your button ID.

AsyncPostBackTrigger or PostBackTrigger

<asp:UpdatePanel ID="UpdatePanel1" runat="server">
<ContentTemplate>
  // HERE  YOUR TEXTBOX AND LABEL CONTROLS 
</ContentTemplate>
 <Triggers>
      <asp:AsyncPostBackTrigger ControlID="Button2"
  </Triggers>
</asp:UpdatePanel>
<asp:Button ID="Button2" runat="server" Font-Bold="False" Font-Names="Tahoma" Font-Size="16px" ForeColor="DarkRed" Height="40px" OnClick="Button2_Click" Text="Clear Form" Width="165px" />

Answer 2

You should place the Textboxes inside update panel as

 <asp:ScriptManager ID="ScriptManager1" runat="server">
            </asp:ScriptManager>
            <asp:UpdatePanel ID="UpdatePanel1" runat="server">
                <ContentTemplate>
                    <asp:TextBox ID="txtFirstName" runat="server"></asp:TextBox>
                    <asp:TextBox ID="txtLastName" runat="server"></asp:TextBox>
                    <asp:TextBox ID="txtEmail" runat="server"></asp:TextBox>
                    <asp:TextBox ID="txtSubject" runat="server"></asp:TextBox>
                    <asp:TextBox ID="txtMessage" runat="server"></asp:TextBox>

                    <asp:Button ID="Button2" runat="server" Font-Bold="False" Font-Names="Tahoma" Font-Size="16px" ForeColor="DarkRed" Height="40px" OnClick="Button2_Click" Text="Clear Form" Width="165px" />
                </ContentTemplate>
            </asp:UpdatePanel>

Answer 3

I have tried and the button code is working .aspx code

<div>
     <asp:ScriptManager ID="ScriptManager1" runat="server">
            </asp:ScriptManager>
            <asp:UpdatePanel ID="UpdatePanel1" runat="server">
                <ContentTemplate>
                    <asp:TextBox ID="txtFirstName" runat="server"></asp:TextBox>
                    <asp:TextBox ID="txtLastName" runat="server"></asp:TextBox>
                    <asp:TextBox ID="txtEmail" runat="server"></asp:TextBox>
                    <asp:TextBox ID="txtSubject" runat="server"></asp:TextBox>
                    <asp:TextBox ID="txtMessage" runat="server"></asp:TextBox>


                    <asp:Button ID="Button2" runat="server" Font-Bold="False" Font-Names="Tahoma" Font-Size="16px" ForeColor="DarkRed" Height="40px" OnClick="Button2_Click" Text="Clear Form" Width="165px" />
                </ContentTemplate>
            </asp:UpdatePanel>
    </div>

.aspx.cs page coding

protected void Button2_Click(object sender, EventArgs e)
        {
            txtFirstName.Text = string.Empty;
            txtLastName.Text = string.Empty;
            txtEmail.Text = string.Empty;
            txtSubject.Text = string.Empty;
            txtMessage.Text = string.Empty;
        }