Memcached Question posted in
A decent usage manual can be found here.

Memcached – Return JSON from a Python Class to Another Class

How would I return the same exact JSON data from one class to another?

Code:

class Class1(webapp.RequestHandler):
    def get(self):
        random_id = str(uuid.uuid1())
        time_now = int(time.time())
        info = {
            id: random_id,
            now: time_now
        }

       json_info = json.dumps(info)
       print json_info
       self.response.write(info)

class Class2(webapp.RequestHandler):
    def get(self):
        getting_info = self.Class1()
        getting_info_time = getting_info['now']
        print getting_info_time

Error:

class1_info = self.Class1()

AttributeError: ‘Class2’ object has no attribute ‘Class1’

Edit (more details):

One part of my application needs the whole JSON output while the other part needs just the now value from the info dictionary. And both classes would be using the same exact data from the info dictionary.

I’ve been trying to get the now output but I just get error messages.

Attempt:

Note: using @Alex’s answer (with @snakecharmerb recommendation of memcache)

Code:

from google.appengine.api import memcache 

class Class1(webapp.RequestHandler):
    def generate_data(self):
        random_id = str(uuid.uuid1())
        time_now = int(time.time()))

        id_cached = memcache.add(key=random_id, value=random_id, time=600)
        get_id_cached = memcache.get(key=random_id, value=random_id, time=600)

        time_cached = memcache.add(key=time_now, value=time_now, time=600)
        get_time_cached = memcache(key=time_now)

        info = {
            id: get_id_cached,
            now: get_time_cached
        }

       json_info = json.dumps(info)
       return json_info

    def get(self):
        self.response.write(generate_data())

class Class2(webapp.RequestHandler):
    def get(self):
        getting_info = Class1().generate_data()
        print getting_info

Result:

{“id”: “9d752605-a20d-11e7-8bfd-bfe81b332704”, “time”: “1506356501”}

{“id”: “9b95e899-a20d-11e7-b137-bfe81b332704”, “time”: “1506356498”}

Tags:

2

Answers


  1. 0

    It would help to know more about what you’re trying to do, but based on your code snippet, this should do it.

    Class1(webapp.RequestHandler):

    @staticmethod
    def perform():
        random_id = str(uuid.uuid1())
        time_now = int(time.time()))
        info = {
            id: random_id,
            now: time_now
        }

       json_info = json.dumps(info)
       print json_info
       return json_info

    def get(self):
       self.response.write(self.perform())

Class2(webapp.RequestHandler):
    def get(self):
        getting_info = Class1.perform()
        getting_info_time = getting_info['now']
        print getting_info_time

    Another route would be having Class2 inherit Class1, another route would be moving the ‘perform’ function outside at the file level. It’s hard to give a more appropriate answer without more context.

    Edit:
    Creating a ‘BaseHandler’ that both classes inherit seems more appropriate then. Check for existence of the cached ID, if None, create & add. 

    RANDOM_ID = "RANDOM_ID"

MyBaseHandler(webapp.RequestHandler):

    @staticmethod
    def get_random_id():
        cached = memcache.get(key=RANDOM_ID)
        if not cached:
            cached = {id: str(uuid.uuid1()), now: int(time.time()))}
            memcache.add(key=RANDOM_ID, value=cached, time=600)
        return cached

Class1(MyBaseHandler):

    def get(self):
       self.response.write(self.get_random_id())

Class2(MyBaseHandler):
    def get(self):
        print self.get_random_id()['now']
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  2. 0

    If both handlers need to access the same data, delegate the data generation to a function.

    def generate_data():
    random_id = str(uuid.uuid1())
    time_now = int(time.time()))
    info = {
        id: random_id,
        now: time_now
    }
    return info


Class1(webapp.RequestHandler):

    def get(self):
       info = generate_data()
       json_info = json.dumps(info)
       print json_info
       self.response.write(info)


Class2(webapp.RequestHandler):

    def get(self):
        info = generate_data()
        getting_info_time = info['now']
        print getting_info_time

    This approach will work if the data is newly generated for each request. If you need to return the same data for each request then you need to store it for example in the datastore, memcache or a session so that it can be retrieved.

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