Why is File.exists (Filename) statement not working? - asp.net

Question

This is my code
protected void btnAdd_Click(object sender, EventArgs e)
{
if (FileUploadControl.HasFile)
{
try
{
string filename = Path.GetFileName(FileUploadControl.FileName);
switch(SubDrpDownList.SelectedIndex)
{
case 0:
if (!File.Exists(filename))
FileUploadControl.SaveAs(Server.MapPath("~/Books/Math/") + filename);
else if (File.Exists(filename))
{
throw new DuplicateWaitObjectException();
}
break;
case 1:
if (!File.Exists(filename))
FileUploadControl.SaveAs(Server.MapPath("~/Books/Physics/") + filename);
else if (File.Exists(filename))
{
throw new DuplicateWaitObjectException();
}
break;
case 2:
if (!File.Exists(filename))
FileUploadControl.SaveAs(Server.MapPath("~/Books/Drawing/") + filename);
else if (File.Exists(filename))
{
throw new DuplicateWaitObjectException();
}
break;
}
lblStatus.Text = "Upload status: File uploaded!";
}
catch (Exception ex)
{
lblStatus.Text = "Upload status: The file could not be uploaded. The following error occured: " + ex.Message;
}
}
}
According to the category, I want books to be uploaded on diffrenet folder which i have achieved using switch statement. Problem is when i upload a book and then for the second time again upload it , File.Exists(filename) doesn't work. What I want is If i upload the same file twice, I want to throw an exception that duplicate file has been trying to be uploaded. But in case of case statement only line !File.Exists(filename)) gets executed even in case of duplicate file. Why is File.Exists(filename)) not getting executed??

Answer 1

The issue is that you are checking to see if the file exists based solely off of the filename, and not off of the full path to the file. What it should be is
protected void btnAdd_Click(object sender, EventArgs e)
{
if (FileUploadControl.HasFile)
{
try
{
string filename = Path.GetFileName(FileUploadControl.FileName);
switch(SubDrpDownList.SelectedIndex)
{
case 0:
if (!File.Exists(Server.MapPath("~/Books/Math/") + filename))
FileUploadControl.SaveAs(Server.MapPath("~/Books/Math/") + filename);
else
{
throw new DuplicateWaitObjectException();
}
break;
case 1:
if (!File.Exists(Server.MapPath("~/Books/Physics/") + filename))
FileUploadControl.SaveAs(Server.MapPath("~/Books/Physics/") + filename);
else
{
throw new DuplicateWaitObjectException();
}
break;
case 2:
if (!File.Exists(Server.MapPath("~/Books/Drawing/") + filename))
FileUploadControl.SaveAs(Server.MapPath("~/Books/Drawing/") + filename);
else
{
throw new DuplicateWaitObjectException();
}
break;
}
lblStatus.Text = "Upload status: File uploaded!";
}
catch (Exception ex)
{
lblStatus.Text = "Upload status: The file could not be uploaded. The following error occured: " + ex.Message;
}
}
}
This will account for the fact that where you are uploading the file is different than where you are checking the file exists
Also, the elseif just needs to be else, because it either exists or it doesn't so you don't need to check again that it exists, that is implied by the "else"

Answer 2

I think the problem you have is that you are reducing the full file name (with path) to just the file name here:
string filename = Path.GetFileName(FileUploadControl.FileName);
From that point !File.Exists is always true.
eg. you are reducing "C:\Somepath\myfile.txt" to "myfile.txt" then checking if it exists.