Question

I am trying to send a file’s content to the client in my request, but the only documentation Express has is it’s download function which requires a physical file; the file I am trying to send comes from S3, so all I have is the filename and content.

How do I go about sending the content of the file and appropriate headers for content type and filename, along with the file’s content?

For example:

files.find({_id: id}, function(e, o) {
  client.getObject({Bucket: config.bucket, Key: o.key}, function(error, data) {
    res.send(data.Body);
  });
});

Answer 1

The type of file depends on the file obviously. Have a look at this:

http://en.wikipedia.org/wiki/Internet_media_type

If you know what exactly is your file, then assign one of these to response ( not mandatory though ). You should also add the length of the file to response ( if it is possible, i.e. if it is not a stream ). And if you want it to be downloadable as an attachment, then add Content-Disposition header. So all in all you only need to add this:

var filename = "myfile.txt";
res.set({
    "Content-Disposition": 'attachment; filename="'+filename+'"',
    "Content-Type": "text/plain",
    "Content-Length": data.Body.length
});

NOTE: I’m using Express 3.x.

EDIT: Actually Express is smart enough to count content length for you, so you don’t have to add Content-Length header.