FileResult with MemoryStream gives empty result .. what's the problem?

Question

I'm generating ics files ( iCalendar or RFC 2445 or however you call them) using a library that serializes the ical contents into a MemoryStream, or actually any type of stream.

Here's my chunk of code:

    public ActionResult iCal(int id) {

        MyApp.Event kiEvt = evR.Get(id);

        // Create a new iCalendar
        iCalendar iCal = new iCalendar();

        // Create the event, and add it to the iCalendar
        DDay.iCal.Components.Event evt = iCal.Create<DDay.iCal.Components.Event>();

        // Set information about the event
        evt.Start = kiEvt.event_date;
        evt.End = evt.Start.AddHours(kiEvt.event_duration); // This also sets the duration            
        evt.Description = kiEvt.description;
        evt.Location = kiEvt.place;
        evt.Summary = kiEvt.title;

        // Serialize (save) the iCalendar
        iCalendarSerializer serializer = new iCalendarSerializer(iCal);


        System.IO.MemoryStream fs = new System.IO.MemoryStream();

        serializer.Serialize(fs, System.Text.Encoding.UTF8);

        return File(fs, "text/calendar", "MyApp.wyd."+kiEvt.id+".ics");
    }

My problem is that fs contains some content, but the controller returns empty file - with proper mimetype and filename. I'm most probably missing something with the stream handling but can't figure out what.

Can anybody help me out here? Thanks in advance.

Answer 1

Just a guess: Do you need to Seek back to the start of the stream before you return it?

fs.Seek(0, 0);

Answer 2

iCalendar iCal = new iCalendar();
foreach (CalendarItem item in _db.CalendarItems.Where(r => r.Start > DateTime.Now && r.Active == true && r.CalendarID == ID).ToList())
{
    Event evt = new Event();
    evt.Start = new iCalDateTime(item.Start);
    evt.End = new iCalDateTime(item.End);
    evt.Summary = "Some title";
    evt.IsAllDay = false;
    evt.Duration = (item.End - item.Start).Duration();
    iCal.Events.Add(evt);
}
// Create a serialization context and serializer factory. 
// These will be used to build the serializer for our object. 
ISerializationContext ctx = new SerializationContext();
ISerializerFactory factory = new DDay.iCal.Serialization.iCalendar.SerializerFactory();
// Get a serializer for our object
IStringSerializer serializer = factory.Build(iCal.GetType(), ctx) as IStringSerializer;
if (serializer == null) return Content("");
string output = serializer.SerializeToString(iCal);
var contentType = "text/calendar";
var bytes = Encoding.UTF8.GetBytes(output);
var result = new FileContentResult(bytes, contentType);
result.FileDownloadName = "FileName.ics";
return result;