Alert show when extension of FileUpLoads are not allowed
- by Vy Clarks
I have a asp FileUpload control in my aspx page.
And the code behind to check file's extension and then insert them into database:
private string Write(HttpPostedFile file, string table)
{
string fileNameMain = Path.GetFileName(file.FileName);
// check for the valid file extension
string fileExtension = Path.GetExtension(fileNameMain).ToLower();
if (fileExtension.Equals(".pdf") || fileExtension.Equals(".doc"))
{
...insert fileupload into database
}
else
{
LabelError.Text = "Extension of files are not allowed.";
return null;
}
}
With the code above, it checks the extension and then show the message "Extension of files are not allowed." in a LabelError if the fileupload is not allowed.
Now, I'm required to do the "check-extension" in the other way: at the moment the client click and choose FileUpload, an alert show "Extension of files are not allowed.".
I need a way to make an alert show at the momment the FileUpload choosed in browser. Help!!!!
