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Wednesday, December 12, 2012

Regular expressions to validate file extension before file upload in javascript using asp.net

Here I will explain how to check or validate file type in file upload control using JavaScript and regular expression to check file extension before file upload using JavaScript in asp.net.
I have one page that contains one file upload control to accept files from user and saving it in one folder. Here I need to give permission for user to upload only .doc or .docx files for that I have written validation by using JavaScript to validate files before save it in database.
Here I have some of regular expressions to validate file upload. 

Regular expression to validate file formats for .mp3 or .MP3 or .mpeg or .MPEG or m3u or M3U
Re= /^(([a-zA-Z]:)|(\\{2}\w+)\$?)(\\(\w[\w].*))+(.mp3|.MP3|.mpeg|.MPEG|.m3u|.M3U)$/;
Regular expression to validate file formats for .doc or .docx
Re= /^(([a-zA-Z]:)|(\\{2}\w+)\$?)(\\(\w[\w].*))+(.doc|.docx|.DOC|.DOCX)$/;
Regular expression to validate file formats for .txt or .TXT
Re= /^(([a-zA-Z]:)|(\\{2}\w+)\$?)(\\(\w[\w].*))+(.txt|.TXT)$/;
Regular expression to validate file formats for .jpeg or .JPEG or .gif or .GIF or .png or .PNG
Re= /^(([a-zA-Z]:)|(\\{2}\w+)\$?)(\\(\w[\w].*))+(.jpeg|.JPEG|.gif|.GIF| .png|.PNG)$/;

Here my requirement is to validate file for only .doc or .docx for that I have written following code in aspx page
<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
<title>Untitled Page</title>
<script type="text/javascript" language="javascript">
function validate() {
var uploadcontrol = document.getElementById('<%=FileUpload1.ClientID%>').value;
//Regular Expression for fileupload control.
var reg = /^(([a-zA-Z]:)|(\\{2}\w+)\$?)(\\(\w[\w].*))+(.doc|.docx|.DOC|.DOCX)$/;
if (uploadcontrol.length > 0)
{
//Checks with the control value.
if (reg.test(uploadcontrol))
{
return true;
}
else
{
//If the condition not satisfied shows error message.
alert("Only .doc, docx files are allowed!");
return false;
}
}
} //End of function validate.
</script>
</head>
<body>
<form id="form1" runat="server">
<div>
<table align="center">
<tr>
<td>
<b>Restrict File Upload sample</b> <br />
<asp:FileUpload ID="FileUpload1" runat="server" />
<br />
<asp:Button ID="Button1" runat="server" Text="Button" OnClientClick="return validate();" />
<br />
<asp:Label ID="Label1" runat="server" ForeColor="Red"></asp:Label>
</td>
</tr>
</table>
</div>
</form>
</body>
</html>
 

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