Delete image file

AlexW · April 15th, 2011, 05:34 PM

I'm storing profile pictures in a folder ~/Account/Pictures/... and can save new pictures and update the URL in the database but I'm stuck on how to remove the old one.

Could it be that I'm passing the File.Delete() method a string like: ~/Account/Pictures/b9b57a75-2287-4e8d-8fc9-8c8cc6e5ef5a.jpg

I'm using this code:

Code:

Dim virtualFolder As String = "~/Account/Pictures/"
            Dim physicalFolder As String = Server.MapPath(virtualFolder)
            Dim conString As String = System.Configuration.ConfigurationManager.ConnectionStrings("ConnectionString").ConnectionString
            Dim con As New SqlConnection(conString)

            ' save new picture
            Dim picName As String = Guid.NewGuid().ToString()
            Dim extension As String = Path.GetExtension(PictureUrl.FileName).ToString()
            PictureUrl.SaveAs(Path.Combine(physicalFolder, picName + extension))

            ' delete old picture
            Dim cmdSelect As SqlCommand = New SqlCommand("SELECT [PictureUrl] FROM [UserDetails] WHERE ([UserName] = @UserName)")
            cmdSelect.Parameters.AddWithValue("@UserName", CurrentUser)
            con.Open()
            Dim oldPic As String = cmdSelect.ExecuteScalar()
            File.Delete(oldPic)

            ' update new PictureUrl in DB
            Dim cmdUpdate As SqlCommand = New SqlCommand("UPDATE [UserDetails] SET [PictureUrl] = @PictureUrl WHERE [UserName] = @UserName", con)
            cmdUpdate.Parameters.AddWithValue("@UserName", CurrentUser)
            cmdUpdate.Parameters.AddWithValue("@PictureUrl", virtualFolder + picName + extension)
            'con.Open()
            cmdUpdate.ExecuteNonQuery()
            con.Close()
            con.Dispose()

chroniclemaster1 · April 16th, 2011, 12:28 AM

You just need to make sure you capture the URL to the old image before you delete it. If you can "find" an image via it's URL in the database, then you should be able to use that path to delete the image. Whether you delete the old image before or after updating the URL in the database is up to you. In most cases it shouldn't matter. However, on the off chance that you can't complete the entire procedure, changing the URL before deleting the old image could leave old, unused images lying around, while deleting the image first could leave you with URLs that have not been updated even though you already deleted the images they point to. Since that would leave you with users looking at red Xs instead of their new images, I would probably change the URL first. It's easy enough to maintain outdated images in the background where no user will ever notice. You could even build a script that hunts down any old image in your file structure that doesn't have a corresponding path in the database. There's also probably a pretty simple way from a server admin perspective to be able to tell when the last time a file was downloaded and / or run a report of all images sorted by their last download date. Then you can personally decide how long you're willing to let files "linger" on the server before you delete them.

Imar · April 16th, 2011, 04:31 AM

Quote:

Originally Posted by chroniclemaster1

You just need to make sure you capture the URL to the old image before you delete it.

I think he's already doing that. This code uploads and saves the new image (which means it's already there), finds the URL of the old image, deletes the old image and then saves the URL of the new image in the database. There's about a nano-second time window where the old image no longer exists and before the new image is stored in the database which seems acceptable to me (read on if it's not acceptable for you).

But anyways, the problem lies in this comment:

Quote:

Could it be that I'm passing the File.Delete() method a string like: ~/Account/Pictures/b9b57a75-2287-4e8d-8fc9-8c8cc6e5ef5a.jpg

Yes, exactly. ~/Account... is a virtual path which makes sense in a Web context. However, File.Delete works anywhere in the .NET Framework and as such needs a physical path. You can convert to one using Server.MapPath (just as you do with the Uploads folder when you save the image):

Code:

 
Dim oldPic As String = Server.MapPath(cmdSelect.ExecuteScalar())
File.Delete(oldPic)

Hope this helps,

Imar

P.S. On the off chance that updating the database fails you may want to delete the image after you saved the new URL. This way, you won't accidentally delete an image that is still in use. E.g.:

Code:

 
Dim oldPic As String = cmdSelect.ExecuteScalar()
 
Dim cmdUpdate As SqlCommand = New SqlCommand("UPDATE [UserDetails] SET [PictureUrl] = @PictureUrl WHERE [UserName] = @UserName", con)
...
cmdUpdate.ExecuteNonQuery()
...
File.Delete(oldPic)

AlexW · April 16th, 2011, 07:42 AM

Thanks, should have noticed since I was using Server.MapPath for saving.

I'm trying to stop if from deleting admin.jpg or default.jpg if that is the current users picture when changing it:

Code:

' check pic isnt admin or default
            If Not oldPicVirtual = "~/Account/Pictures/admin.jpg" OrElse Not oldPicVirtual = "~/Account/Pictures/default.jpg" OrElse Not oldPicVirtual = "" Then
                Dim oldPic As String = Server.MapPath(oldPicVirtual)
                File.Delete(oldPic)
            End If

But wierdly the file is still being deleted. While debuggin oldPicVirtual = "~/Account/Pictures/default.jpg" but the if block still executes??? I think something silly is happening here...

Imar · April 16th, 2011, 08:13 AM

You got your Or logic mixed up. You have this:

Code:

 
If it's not Admin Or it's not Default.

When it's Admin, it's not Default and vice versa. This means your code block always runs ;-)

I think you want And instead:

Code:

 
If it's not Admin And it's not Default.

With And, all conditions need to be true. E.g. it can't be Admin and it can't be Default. If one of them matches, the If block won't run:

Code:

 
If Not oldPicVirtual = "~/Account/Pictures/admin.jpg" And Not oldPicVirtual = "~/Account/Pictures/default.jpg" And Not oldPicVirtual = "" Then
  Dim oldPic As String = Server.MapPath(oldPicVirtual)
  File.Delete(oldPic)
End If

Hope this helps,

Imar

AlexW · April 16th, 2011, 08:28 AM

Oh man, I knew it was something silly. Thanks.