Problems with NoRM and GridFS

[John Tsombakos]

I'm trying to use the GridFS capability of the NoRM driver, but have run into a strange problem.

I have code (an ASP.NET site), that when a file is selected, the file is uploaded and put into a Mondo database, using NoRM and GridFS. The first problem where the file wasn't actually stored in the database was fixed by the post: https://groups.google.com/d/msg/norm-mongodb/nzLXGyYwNnA/Ylf9oz-8ogkJ 

The upload code is:

protected void btnUpload_Click(object sender, EventArgs e)

        {

            if (FileUpload1.HasFile)

            {

                    // opens the database and will create the new database if it does not exist

                    using (var server = Mongo.Create("mongodb://server/TestDB")) 

                    {

                        // gets your class object collection

                        var collection = server.GetCollection<Record>(); 

                       

                        Record newRecord = new Record();                        

                       

                        var fs = FileUpload1.FileBytes; // gets the file your uploading

                        

                            var file = new GridFile(); // creates a new mongo file object

                            var fileCollection = server.Database.Files(); //gets the collection of files in the database

                            

                        // set the file properties

                            file.FileName = FileUpload1.FileName;

                            file.Content= fs; // the content of the file

                            file.ContentType = "application/pdf";

                            fileCollection.Save(file); // uploads to the database

                            newRecord.file_id = file.Id; // gets the id of the file that was just uploaded

 

                        // fill in the rest of the class proprties

                            newRecord.filename = FileUpload1.FileName;

                            newRecord.introDesc = txtIntro.Text;

                            newRecord.category = "category1";

                            newRecord.category2 = "category2";

                            newRecord.category3 = "category3";

                            newRecord.dateAdded = DateTime.Today;

                            newRecord.status = "A";

                            newRecord.paid = "yes";

                            newRecord.teaser = txtTeaser.Text;

                            newRecord.title = FileUpload1.FileName;

                            collection.Save(newRecord);

 

                            txtIntro.Text = "";

                            txtTeaser.Text = "";

 

 

                    }

                    lblMsg.Text = "File was uploaded";

                

            }

}

That seems to work fine, I see the entry in the database, both the files collection and the chunks.  Now I have code that, given some criteria, will retrieve the file and stream it to the web page:

        public void showPDF()

        {

            using (var server = Mongo.Create("mongodb://server/TestDB"))

            {

                var collection = server.GetCollection<Record>();

                var q = (from r in collection.AsQueryable()

                         where r.filename == pdfFile

                         select r).FirstOrDefault();                              

                var gridFS = server.Database.Files();// gets the files collection

                //var file = gridFS.FindOne(new{ filename= pdfFile});

                var file = gridFS.FindOne(new { _id = q.file_id });

                var contents = file.Content.ToArray();              

                Response.Clear();

                Response.AddHeader("Content-Length", contents.Length.ToString());

                Response.ContentType = file.ContentType;

                Response.AppendHeader("Content-Disposition", "attachment; filename= " + pdfFile);

                // Write the memory stream containing the file directly to 

                //the Response object that gets sent to the client 

               Response.OutputStream.Write(contents, 0, Convert.ToInt32(contents.Length));

                // Must end response because the rest of the pages html code will 

                //add to the file that is trying to open

                Response.End();

                HttpContext.Current.ApplicationInstance.CompleteRequest();

            }

        }

And that works, the PDF will show/be download... the first time. From there after, even though the file is in the database, examining the file.Content shows the size is 0

Has anyone used the GridFS and run into this problem, the second and subsequent queries return an empty content?

Thanks.