Serving files from GridFS with casbah/salat

Question

I would like to store images uploaded as user content in GridFS in a Scala Play 2 application. How can I restore the binary file from the GridFSDBFile that GridFS.findOne gives me?

Answer 1

You could serve the file by streaming its contents and setting the correct http headers - an example of doing so is here.

def getPhoto(file: ObjectId) = Action {
  import com.mongodb.casbah.Implicits._

  val gridFs = salat.gridFS("photos")

  gridFs.findOne(Map("_id" -> file)) match {
    case Some(f) => SimpleResult(
      ResponseHeader(OK, Map(
        CONTENT_LENGTH -> f.length.toString,
        CONTENT_TYPE -> f.contentType.getOrElse(BINARY),
        DATE -> new SimpleDateFormat("EEE, dd MMM yyyy HH:mm:ss 'GMT'", java.util.Locale.UK).format(f.uploadDate)
      )),
      Enumerator.fromStream(f.inputStream)
    )

    case None => NotFound
  }
}

However, this often isn't the most performant option for serving files. File systems are designed to do that or putting the url root behind a cache - eg varnish or deploying to cdn is often a better choice.