Unwanted data injected into datagrid textbox

[kingflux]

Hello, and thank you in advance for any help you can provide.

Each line in our datagrid control contains a product number, description, and a textbox for the user to enter a quantity-to-order.

Users enter quantities (not necessarily on every line), click the Next button, and continue. Sometimes users return to a previous page, by clicking the Previous button, and see quantities that they did not enter. More often, users return to a previous page to find unwanted quantities added and wanted quantities deleted.

A dozen customers have reported this problem over the last six months, but we have been unable to reproduce it in-house. It is extremely rare, but one week it happened four times.

Has anyone else experienced anything like this? Our solution was developed by a third party, but I am becoming more familiar with the source code and can answer any questions to clarify the issue.

Patterns we have identified
1. There has never been an equal number of items deleted and inserted.
2. The deleted items are always contiguous to one another. (Items are organized by a fixed catalog line number.)
3. The inserted items are always contiguous to one another.

Notes
1. The solution uses custom paging (datagrid.allowpaging=FALSE).
2. This behavior occurs before any records are written to the SQL Server backend. (That happens when the user clicks the Save button or the Place Order button.)
3. Solution was developed in Microsoft Visual Studio .NET 2003.
4. Our in-house Windows PCs are all at Framework level 1.1.4322.2032 (Service Pack 1); the server is also at SP1 level (1.1.4322.2300); am waiting to hear back from two customers what version of the .NET Framework they're using.
5. All clients are using Internet Explorer 6.0.

[kingflux]

I'm happy to announce that we figured out what is happening with the 'unwanted data injected into datagrid textbox' and it is now fixed on our site.

I found the cause purely by accident, when testing on an older server that is significantly slower than our production web server. I found that I could click the Next button multiple times while I waited 5-8 seconds between page loads. Whenever I did, it "jumped" the same number of pages and copied the values from the first page to all the subsequent pages that were "touched" in the transaction. Nothing on the screen would ever suggest to the user that such a thing had occurred.

Mr. Barker from sqlwork.com got me on the right track when he suggested duplicate postback was the likely problem.

At the bottom of the page, just before the closing HTML tag, we added this javascript code, which disables all buttons on the page and displays a "Processing..." message until the next page loads:

<script language="javascript">
    /* Code to fix multi-click issue */
    
    // handle the unload of the form
    window.attachEvent("onbeforeunload", disableWindowControlsOnUnload);
    
    // loop through relevant input controls and make sure the users do attempt a postback
    var elementCollection = document.getElementsByTagName("input");
    if ( elementCollection != null )
    {
        for ( var i = 0; i < elementCollection.length; i++ )
        {
            var element = elementCollection(i);
            if ( element.type == "submit" || element.type == "button" )
            {
                element.attachEvent("onclick", disableWindowControlsOnClick);
                element.attachEvent("ondblclick", handleDoubleClick);
            }
        }
    }

    // this method used to disable any input controls from firing
    function disableWindowControlsOnUnload()
    {
        document.body.style.cursor = "wait";
        for ( var j = 0; j < document.forms.length; j++ )
        {
            var elementCollection = document.forms(j).getElementsByTagName("input");            
            for ( var i = 0; i < elementCollection.length; i++ )
            {
                var element = elementCollection(i);
                if ( thisElement.type == "submit" || thisElement.type == "button" )
                    element.disabled = true;
            }
        }
        
        return true;
    }

    // this will make sure no events create a double post scenario
    var bubbleEvent = true;
    function disableWindowControlsOnClick()
    {
        if ( bubbleEvent == true )
        {
            document.body.style.cursor = "wait";
            showProcessingBanner();
            bubbleEvent = false;
        }
        else
        {
            window.event.cancelBubble = false;
            window.event.returnValue = false;
        }
    }
    
    function handleDoubleClick()
    {
            window.event.cancelBubble = false;
            window.event.returnValue = false;
    }
    
    
    function showProcessingBanner()
    {
        var bannerElement = "<div style='position:absolute; z-index:99; border-style:solid; background-color:white; width:400px; height:200px;'></div>";
        var banner = document.createElement(bannerElement);
        
        banner.innerHTML = "<span style='color:black; font-size:large; vertical-align:middle;'><center><br><br><br>Processing...</center></span>";
        banner.style.left = ( window.screen.availWidth / 2 ) - 200;
        banner.style.top  = ( window.screen.availHeight / 2 ) - 100;
        document.body.insertBefore(banner);
    }
    
    </script>