File Stream not return after closing it in finally block C#

Question

I have download files by returning as stream like below using WCF rest service.

 Stream stream = null;          
            var directoryInformation = CommonServices.Utility.DirectoryHelper.GetTempFolderRootLocation();
            string newFolderPath = directoryInformation + "\\Attachments\\" + Guid.NewGuid();
            try
            {

                Directory.CreateDirectory(newFolderPath);
                DataSet getDocumentContent = GetDocumentContent(engagementId, documentId);
                var fileName = getDocumentContent.Tables[0].Rows[0]["Fullname"] as string;
                var byteData= getDocumentContent.Tables[0].Rows[0]["FilestreamContent"] as byte[];
                string fullPath = newFolderPath + "\\" + fileName;        
                using (var fileStream = new FileStream(fullPath, FileMode.Create))
                {
                    if (byteData != null)
                    {
                        fileStream.Write(byteData,0,byteData.Length);
                        fileStream.Close();
                    }

                    if (WebOperationContext.Current != null)
                    {
                        WebOperationContext.Current.OutgoingResponse.ContentType = "application/octet-stream";
                        WebOperationContext.Current.OutgoingResponse.Headers.Add("content-disposition","inline; filename=" + fileName);
                    }
                }
                stream = File.OpenRead(fullPath);
                return stream;
            }
            catch (Exception exception)
            {

                return null;
            }

The above code works perfectly and can download the file in browser. But i have to delete the file after return the stream. So i have try to close and delete the file including the directory in finally block like below

   finally
            {
                if (stream != null) stream.Close();
                Directory.Delete(newFolderPath, true);
            }

Full Method code

 public Stream DownloadAttachment(string engagementId, string documentId)
        {
            Stream stream = null;          
            var directoryInformation = CommonServices.Utility.DirectoryHelper.GetTempFolderRootLocation();
            string newFolderPath = directoryInformation + "\\Attachments\\" + Guid.NewGuid();
            try
            {

                Directory.CreateDirectory(newFolderPath);
                DataSet getDocumentContent = GetDocumentContent(engagementId, documentId);
                var fileName = getDocumentContent.Tables[0].Rows[0]["Fullname"] as string;
                var byteData= getDocumentContent.Tables[0].Rows[0]["FilestreamContent"] as byte[];
                string fullPath = newFolderPath + "\\" + fileName;        
                using (var fileStream = new FileStream(fullPath, FileMode.Create))
                {
                    if (byteData != null)
                    {
                        fileStream.Write(byteData,0,byteData.Length);
                        fileStream.Close();
                    }

                    if (WebOperationContext.Current != null)
                    {
                        WebOperationContext.Current.OutgoingResponse.ContentType = "application/octet-stream";
                        WebOperationContext.Current.OutgoingResponse.Headers.Add("content-disposition","inline; filename=" + fileName);
                    }
                }
                stream = File.OpenRead(fullPath);
                return stream;
            }
            catch (Exception exception)
            {

                return null;
            }
           finally
            {
                if (stream != null) stream.Close();
                Directory.Delete(newFolderPath, true);
            }
        }

After adding this code file is not downloaded in client.Is there any way to delete the file?Please help me to resolve this

Did you add this finally block at the end of the mentioned method? If so, `Close` will dispose the same stream you're trying to return. — Yuval Itzchakov, Nov 14 '14 at 10:16
could you please look at the source code.i have updated my question by adding the full method — Jameel Moideen, Nov 14 '14 at 10:19
actuall i have return stream after reading a file from server so browser will download this file based on the content type. But after return the stream i have to delete that file. When i try to delete this file without close it shows an exception file is used by another process — Jameel Moideen, Nov 14 '14 at 10:24
You can't return a `FileStream` to a file which you want to delete because the `FileStream` will hold a handle to that file. Why not return a byte[] with the file instead? — Yuval Itzchakov, Nov 14 '14 at 10:25
See how try catch finally with return statement works [here](http://stackoverflow.com/questions/421797/what-really-happens-in-a-try-return-x-finally-x-null-statement) — b2zw2a, Nov 14 '14 at 10:27
but the code is working fine and downloaded the file in browser. The only pblm is when i try to close in finally i think the stream get clear — Jameel Moideen, Nov 14 '14 at 10:27
It gets disposed when you call `stream.Close()`. You need to re-think what you're doing. — Yuval Itzchakov, Nov 14 '14 at 10:28
is there any way to achieve the download and delete functionality together? — Jameel Moideen, Nov 14 '14 at 10:29
Yes.I have to return the stream else it will not download the file in browser — Jameel Moideen, Nov 14 '14 at 10:36

score 1 · Accepted Answer · answered Nov 14 '14 at 10:32

You can delete the file in OperationContext.OperationCompleted as shown in http://devdump.wordpress.com/2008/12/07/disposing-return-values/

OperationContext clientContext = OperationContext.Current;
clientContext.OperationCompleted += new EventHandler(delegate(object sender, EventArgs args)
   {
          if (stream != null) stream.Close();
          Directory.Delete(newFolderPath, true);
   });

score 0 · Answer 2 · answered Nov 14 '14 at 10:34

Change your method to this.

public void DownloadAttachment(string engagementId, string documentId, Action<Stream> processFile)

and instead of returning the stream call the processFile Action

processFile(stream);

This way you're not leaving the method in order to process the file. You will need to restructure the calling code in order to process the file though.

File Stream not return after closing it in finally block C#

2 Answers2