Javascript To Verify File Upload

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Hi,

I am hoping someone can help me with a problem regarding validating a file upload control in asp.net.

I have a reservation system, where you can reserve tickets. it is built in asp.net 4.5 and c#. When you choose the number of tickets you want, you are brought to a page to enter all personal details as well as upload a photo for each passenger. If you choose to buy 3 tickets you will be shown a gridview with 3 rows, each row has text boxes for your details as well as a file upload control for each user, and a button which uploads the file for that user.

My problem is, lets say you are booking for 3 users, you will have 3 file upload controls and 3 file upload buttons. Lets say you select your file for each of the 3 controls but you forget to click the upload button for each user. When the user tries to go to the next page i need to tell them that they forgot to click the upload button on each of the controls. I am already doing this on the server side which works fine, but my problem is, after the page posts back the file upload controls loose their selected files. I know why the file upload controls loose their value, that is fine, my problem is, how do i remind the user to click the upload button using javascript if they have not clicked the button. Please remember the file upload controls are generated in a grdivew so the html id of each control will be different and dynamic.

I assume javascript is needed, or could i use one of the asp.net validators.

Thanks
David

Posted 10-Dec-14 8:39am

David Brosnan

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Kornfeld Eliyahu Peter 10-Dec-14 16:35pm

Not clear...
Standard upload control will upload the selected file upon page post-back without further action from the user!

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Ishpreet Kaur · Answer 1 · 2014-12-10T17:42:00

You can do as following:

JavaScript

<script>
$(document).ready(function(){
$(':input').bind('change', function() { setConfirmUnload(true); });
$('#btnsavephoto').click(function() { setConfirmUnload(false); });
function setConfirmUnload(on)
            {
                window.onbeforeunload = on ? unloadMessage : null;
            }
            function unloadMessage()
            {
                return ('You have attempted to leave this page. ' +
                        'If you have made any changes to the fields without clicking the Save button, ' +
                        'your changes will be lost.');
            }
});
</script>

I have written this line in above script: