title: Error: "could not find implicit value for parameter readFileReader" trying to save a file using GridFS with reactivemongo
body: <p>I am trying to save an attachment using reactivemongo in Play 2.1 using the following code:</p>
  
  <pre><code>def upload = Action(parse.multipartFormData) { request =&gt;
      request.body.file("carPicture").map { picture =&gt;
      val filename = picture.filename
      val contentType = picture.contentType
  
      val gridFS = new GridFS(db, "attachments")
      val fileToSave = DefaultFileToSave(filename, contentType)
  
      val futureResult: Future[ReadFile[BSONValue]] = gridFS.writeFromInputStream(fileToSave, new FileInputStream(new File(filename)))
  
      Ok(Json.obj("e" -&gt; 0))
    }.getOrElse {
      Redirect(routes.Application.index).flashing(
        "error" -&gt; "Missing file"
      )
    }
  }
  </code></pre>
  
  <p>I am getting the following error:</p>
  
  <p>could not find implicit value for parameter readFileReader: reactivemongo.bson.BSONDocumentReader[reactivemongo.api.gridfs.ReadFile[reactivemongo.bson.BSONValue]]
  [error]       val futureResult: Future[ReadFile[BSONValue]] = gridFS.writeFromInputStream(fileToSave, new FileInputStream(new File(filename)))</p>
  
  <p>What am I missing?</p>
  
  <p>Thanks,</p>
  
  <p>GA</p>