Restricting File Types

There are times when you may need to restrict the type of files saved on the Web server. You can do so by using FileUp's ContentTypeproperty and a Select condition to save only files that are a certain type.

Once your file is uploaded, you would include the following after creating an instance of FileUp:

Server-Side Code

Server-Side Code
<% '--- Get the uploaded file's content-type and '--- assign it to a variable. FCONT = fileUpload.ContentType '--- Use the Select Case Condition to restrict the file type. Select Case LCase(FCONT) Case "image/gif" fileUpload.Save Response.Write "<P>" & fileUpload.ShortFileName & " has been saved." Case "image/pjpeg" fileUpload.Save Response.Write "<P>" & fileUpload.ShortFileName & " has been saved." Case Else fileUpload.delete Response.Write "<P>" & "You can only upload gif and jpeg files.<br />" Response.End End Select .... %>

<%
                
'--- Get the uploaded file's content-type and
                
'--- assign it to a variable.
FCONT = fileUpload.ContentType
                

'--- Use the Select Case Condition to restrict the file type.
Select Case LCase(FCONT)
                
Case "image/gif"
fileUpload.Save
                
Response.Write "<P>" & fileUpload.ShortFileName
                & " has been saved."

Case "image/pjpeg"
                
fileUpload.Save
                
Response.Write "<P>" & fileUpload.ShortFileName
                & " has been saved."

Case Else
fileUpload.delete
Response.Write "<P>" & "You can only
                upload gif and jpeg files.<br />"
Response.End
                
End Select
....
%>

We get the media content-type of the file uploaded by using the ContentTypeproperty. In this example, we accept only .gif and .jpeg files. So we are looking for either "image/pjpeg" or "image/gif" as the media content-type.

A Case condition statement is used to save the correct file and send a successful response. Notice that the property ShortFileNameis used to supply the name of the file that was saved. If the file type is incorrect, the file will be deleted and an error response will sent.

Summary

To restrict a file by media type, identify the media content of an uploaded file using the ContentTypeproperty, and use a Select Case condition statement.
Alternately, to restrict a file by file name extension, identify a file's original name, without the original path, by using ShortFileNameand parsing for the extension.
To restrict the types of files to be uploaded before they leave the client, consider using an intelligent client such as SoftArtisans XFile. Please see Restricting File Size and Type Before Uploading.

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