Preventing Multiple Submit Button Clicks in C#

When handling form submissions, a common issue is users clicking the submit button multiple times, which can cause duplicate processing or other errors. Here are several approaches to prevent this:

Client-side Solutions

1. JavaScript Approach

// In your .aspx page or view:

<script type="text/javascript">

    function preventMultipleClicks(button) {

        // Disable the button

        button.disabled = true;

        button.value = "Processing...";

        

        // Submit the form

        return true;

    }

</script>

<asp:Button ID="btnSubmit" runat="server" Text="Submit" 

    OnClientClick="return preventMultipleClicks(this);" 

    OnClick="btnSubmit_Click" />

2. Using jQuery

        <script src="https://code.jquery.com/jquery-3.6.0.min.js"></script>

<script type="text/javascript">

    $(document).ready(function() {

        var form = $("form");

        form.submit(function() {

            $(this).find(':submit').attr('disabled', 'disabled')

                .val('Processing...');

        });

    });

</script>

Server-side Solutions

1. Using a Flag in the Session or ViewState

protected void btnSubmit_Click(object sender, EventArgs e)

{

    // Check if already processing

    if (ViewState["IsProcessing"] != null && (bool)ViewState["IsProcessing"])

    {

        // Already processing, ignore this click

        return;

    }

    try

    {

        // Set processing flag

        ViewState["IsProcessing"] = true;

        

        // Your processing logic here

        ProcessForm();

    }

    finally

    {

        // Reset flag when done

        ViewState["IsProcessing"] = false;

    }

}

2. Using Page.IsValid and Disabling Button

            

    protected void btnSubmit_Click(object sender, EventArgs e)

{

    if (Page.IsValid)

    {

        // Disable the button to prevent multiple clicks

        Button btn = (Button)sender;

        btn.Enabled = false;

        

        // Process form

        ProcessForm();

        

        // Optionally re-enable the button if staying on the same page

        // btn.Enabled = true;

    }

}

3. Using a Hidden Field to Track Submission

<asp:HiddenField ID="hdnSubmitted" runat="server" Value="false" />

protected void btnSubmit_Click(object sender, EventArgs e)

{

    if (hdnSubmitted.Value == "false")

    {

        hdnSubmitted.Value = "true";

        

        // Process form

        ProcessForm();

    }

    else

    {

        // Already submitted, ignore

    }

}

Best Practices

• Combine client-side and server-side approaches for maximum reliability
• Always include server-side validation as client-side can be bypassed
• Consider adding a short timer to re-enable the button if appropriate
• For AJAX forms, use a loading indicator to provide visual feedback