Avoid attaching a 0 KB file to file upload control

Question

In my ASP website I have a form with some textbox, a file upload control and submit form option. I want to avoid users from attaching 0 KB file. I can get the size in my vb code in the background. But how can I get file size and avoid the users from attaching it. I want to give a validation message to the user if they attach a 0 kb file. How it can be done?

score 2 · Answer 1 · edited May 23 '17 at 11:57

2

Answered here: StackOverflow question

Use Javascript to validate a files size before upload. Can be achieved using the File API included in most modern browsers.

var input = document.getElementById('file');
if(input.files[0].size<1000) alert('Please make the file at least 1kb!');

edited May 23 '17 at 11:57

Community

1
1

answered Jul 02 '14 at 07:34

James Hunt

2,448
11
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It does not work in IE8 gives error Error: 'files.0' is null or not an object . But works in chrome – IT researcher Jul 02 '14 at 08:04
Polyfill for backwards compatibility of File API - https://github.com/Jahdrien/FileReader – James Hunt Jul 02 '14 at 08:18

score 0 · Answer 2 · answered Jul 02 '14 at 07:35

0

You can do it on client side, as given:

function GetFileSize(fileid) {
    try {
        var fileSize = 0;
        //for IE
        if ($.browser.msie) {
            //before making an object of ActiveXObject, 
            //please make sure ActiveX is enabled in your IE browser
            var objFSO = new ActiveXObject("Scripting.FileSystemObject"); var filePath = $("#" + fileid)[0].value;
            var objFile = objFSO.getFile(filePath);
            var fileSize = objFile.size; //size in kb
            fileSize = fileSize / 1048576; //size in mb 
        }
            //for FF, Safari, Opeara and Others
        else {
            fileSize = $("#" + fileid)[0].files[0].size //It will calculate file size in kb

             // Put Your Alert or Validation Message Here


        }

    }
    catch (e) {
        alert("Error is :" + e);
    }
}

answered Jul 02 '14 at 07:35

Pawan

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ok. But answer from James Hunt appears easy and simple. Is there any disadvantage in using that method? – IT researcher Jul 02 '14 at 08:01
yes, may be..but make sure that works in all browsers ;) – Pawan Jul 02 '14 at 08:02
The above code also didn't work in IE 8. Because `filePath` will be set to fake path(like C:\fakepath\New Text Document.txt instead of real path of file), not the actual path. so objFile.size; command files and gives error like file not found – IT researcher Jul 02 '14 at 12:53

Avoid attaching a 0 KB file to file upload control

2 Answers2