title: return empty JSON by Flask
body: <p>I have a simple functions, which should returns JSON.</p>
  
  <pre><code>@app.route('/storage/experiments', methods=['GET'])
  def get_experiments():
      if not request.json:
          abort(400)
      experiments = db['experiments']
      cursor = experiments.find(request.get_json())
      print(dumps(cursor))
      resp = Response(response=dumps(cursor),
      status=200, \
      mimetype="application/json")
      return resp
  </code></pre>
  
  <p>print(dumps(cursor)) shows</p>
  
  <p><code>[{"current": "11", "date": "12.12.2001", "_id": {"$oid": "551c7b642349c517f5fa5223"}, "name": "xaxa", "voltage": "34"}]</code></p>
  
  <p>but returns empty brackets []</p>