Python futures : How do I get the json from a future object in Tornado? -

this post handler :

handler.py

from imports import logic  @gen.coroutine def post(self):     data = self.request.body.decode('utf-8')     params = json.loads(data)     model_id= params['model_id']     logic.begin(model_id) 

the logic object imported imports.py instantiated imported class logic

imports.py :

import models import logic  class persist(object):     def getmodel(self, model_id):         model = models.findbymodelid(model_id)         return model   persist = persist() logic = logic(persist) 

logic.py

class logic(object):     def __init__(self, persist):         self._persist = persist      def begin(self, model_id):          model = self._persist.get_model(model_id)          print ("model persist : ")          print (model) 

the get_model method uses models makes db query , returns future object :

model.py:

from motorengine.document import document  class models(document):     name = stringfield(required=true)  def findbymodelid(model_id):     return models.objects.filter(_id=objectid(model_id)).find_all() 

this prints future object in console :

<tornado.concurrent.future object @ 0x7fbb147047b8> 

how can convert json ?

to resolve future actual value, yield inside coroutine:

@gen.coroutine def begin(self, model_id):      model = yield self._persist.get_model(model_id)      print ("model persist : ")      print (model) 

any function calls coroutine must coroutine, , must yield return value of coroutine return value:

@gen.coroutine def post(self):     data = self.request.body.decode('utf-8')     params = json.loads(data)     model_id = params['model_id']     model = yield logic.begin(model_id)     print(model) 

more advanced coding patterns don't need follow these rules, begin with, follow these basic rules.

for more information calling coroutines coroutines, see refactoring tornado coroutines.