Send Attachment File from CouchDB to user?

Question

i'm new to CouchDB and recently i create download portal using Express. I want to make sure that only authorize users will able to download so i create checking procedure in app.js (using express) like this :

app.get("/download/:id/:file", function (req, res) {
   var filename = req.params.file;
   var docI= req.params.id;
   if(userHasPrivileges()){
       db.getAttachment(publicationID, filename, function(err, reply){
           // WHAT SHOULD I DO HERE ?
       })
   }
}

the problem is i can't make cradle.io (https://github.com/cloudhead/cradle#creatingupdating-documents) to send the file directly to user. I don't want to use direct link from database, since it'll make unauthorized user be able to download file. The problem is: i don't really know how to send file that I just get from getAttachment() method to user's browser.

Thx for help

Answer 1

In couchdb, db.getAttachment return a Stream, so you can pipe that stream to http response object:

getAttachment().pipe(httpResponseObject)  

Full code:

app.get("/download/:id/:file", function (req, res) {
   var filename = req.params.file;
   var docI= req.params.id;
   if(userHasPrivileges()){
       res.attachment(filename);
       db.getAttachment(publicationID, filename, function(err){ }).pipe(res);
   }
}

If your attachments are big data such as big images, mp3s or videos, you should support range download. Range in headers may allow browsers download/re-download the part they need.

Nodejs - HTTP Range support / Partial file download