So my basic question. I have a flask application. Inside of this application I have built a simple login system that uses flask sessions. I want to break my code
up into different classes to help separate my logic. But i am receiving the following error.
Traceback (most recent call last):
File "server.py", line 22, in <module>
securty = Security()
File "/Users/chrisburgin/Development/pigarage/security.py", line 6, in __init__
print(session.get('logged_in'))
NameError: global name 'session' is not defined
This error is receiving using the following.
My External Class
class Security:
def __init__(self):
print('Security Created')
print(session.get('logged_in'))
def loggedIn(self):
if session.get('logged_in') != True:
return False
And I am calling this from inside of my server file
securty = Security()
Just as summery. I understand that the 'Security' class doesn't have access to session because its not in scope but I could very much use assistance in understanding how to provide it access.
Please correct me on anything I have done wrong. Thanks!
editing using from flask import session at the top of my external class file
File "server.py", line 22, in <module>
securty = Security()
File "/Users/chrisburgin/Development/pigarage/security.py", line 5, in __init__
print(session.get('logged_in'))
File "/Library/Python/2.7/site-packages/werkzeug/local.py", line 338, in __getattr__
return getattr(self._get_current_object(), name)
File "/Library/Python/2.7/site-packages/werkzeug/local.py", line 297, in _get_current_object
return self.__local()
File "/Library/Python/2.7/site-packages/flask/globals.py", line 20, in _lookup_req_object
raise RuntimeError('working outside of request context')
RuntimeError: working outside of request context
The session variable from Flask is a context local. Context locals are a somewhat special type of global variable, in that they are only accessible at certain times.
Specifically for session, you can only use it when the application is responding to a request. Flask sets the value of this variable right before invoking a view function.
In your stack trace, it appears you are creating an instance of the Security class during initialization. The constructor for this class accesses session, but at this time, there is really no client, no request, and no session, so this gives you an error. It's okay to create an object of this class, as long as you don't access the session in the constructor. Then you must make sure that you invoke the loggedIn method only inside a view function or a function called from a view function, to ensure a request context exists.
Related
In Flask I'm attempting to run several jobs concurrently. But I'm faced with this issue:
This typically means that you attempted to use functionality that needed
to interface with the current application object in some way. To solve
this, set up an application context with app.app_context(). See the
documentation for more information.
Job "chron (trigger: interval[0:00:05], next run at: 2020-05-19 16:03:46 IST)" raised an exception
Traceback (most recent call last):
File "C:\Users\mithi\AppData\Local\Programs\Python\Python37\lib\site-packages\apscheduler\executors\base.py", line 125, in run_job
retval = job.func(*job.args, **job.kwargs)
File "c:\Users\mithi\Desktop\appengineering\server.py", line 128, in chron
return jsonify({})
File "C:\Users\mithi\AppData\Local\Programs\Python\Python37\lib\site-packages\flask\json\__init__.py", line 358, in jsonify
if current_app.config["JSONIFY_PRETTYPRINT_REGULAR"] or current_app.debug:
File "C:\Users\mithi\AppData\Local\Programs\Python\Python37\lib\site-packages\werkzeug\local.py", line 348, in __getattr__
return getattr(self._get_current_object(), name)
File "C:\Users\mithi\AppData\Local\Programs\Python\Python37\lib\site-packages\werkzeug\local.py", line 307, in _get_current_object
return self.__local()
File "C:\Users\mithi\AppData\Local\Programs\Python\Python37\lib\site-packages\flask\globals.py", line 52, in _find_app
raise RuntimeError(_app_ctx_err_msg)
RuntimeError: Working outside of application context.
Here is my schedular object:
job_defaults = {
'coalesce': False,
'max_instances': 100
}
sched = BackgroundScheduler(daemon=True, job_defaults=job_defaults)
sched.start()
I'm creating multiple jobs by defining the following function:
def etl():
# read app config
with open('appConfig.json', encoding="utf-8") as json_file:
configData = json.load(json_file)
for obj in configData:
sched.add_job(chron, 'interval', seconds=5, args=[obj], id=obj)
Basically the function is adding jobs as a call to the function "chron" but args and id are different which creates unique jobs, running at intervals of five seconds. I get the app_context issue in the chron function. I have read about app_context but still unable to grasp the concept.
Your "chron" function is calling Flask current_app and jsonify() but it seems you haven't pushed a Flask context yet thus having this outside app context runtime error.
Before you can call a "contexted" func, you need to push your Flask app context.
Two ways of doing so,
app = Flask(__name__)
# do some stuff on your app if you need
app.app_context().push()
# do some other stuff
or in your chron func,
with app.app_context():
# do something
You can refer to manually pushing a context for more details
I've created a task that adds a value to session so then i can access it through browser , my celery is running perfectly, here are my codes:
from flask import session, g
from ..extensions import celery
CELERYBEAT_SCHEDULE = {
'add-every-10-seconds': {
'task': 'tasks.ruble',
'schedule': timedelta(seconds=20)
}
}
#celery.task(name='tasks.ruble')
def ruble():
url = 'https://finance.google.com/finance/converter?a=1&from=KGS&to=RUB&meta=ei%3DmSr0WeHCCYvBsAH8n6OIBA'
urlHandler = urllib2.urlopen(url)
html = urlHandler.read()
bsoup = BeautifulSoup(html, 'lxml')
num = bsoup.find('span').text.split()[0]
g.get('ruble', float(num))
session['get_ruble'] = float(num)
but when the times come to execute the task, it ends up with this error:
[2017-10-30 19:19:29,372: ERROR/PoolWorker-4] Task tasks.ruble[ff7617ad-764b-455c-b541-96f3ba78a87b] raised unexpected: RuntimeError('Working outside of request context.\n\nThis typically means that you attempted to use functionality that needed\nan active HTTP request. Consult the documentation on testing for\ninformation about how to avoid this problem.',)
Traceback (most recent call last):
File "/home/xakep/Desktop/work/optomvse/venv/local/lib/python2.7/site-packages/celery/app/trace.py", line 367, in trace_task
R = retval = fun(*args, **kwargs)
File "/home/xakep/Desktop/work/optomvse/celery_worker.py", line 21, in __call__
return TaskBase.__call__(self, *args, **kwargs)
File "/home/xakep/Desktop/work/optomvse/venv/local/lib/python2.7/site-packages/celery/app/trace.py", line 622, in __protected_call__
return self.run(*args, **kwargs)
File "/home/xakep/Desktop/work/optomvse/develop/tasks.py", line 34, in ruble
session['get_ruble'] = float(num)
File "/home/xakep/Desktop/work/optomvse/venv/local/lib/python2.7/site-packages/werkzeug/local.py", line 350, in __setitem__
self._get_current_object()[key] = value
File "/home/xakep/Desktop/work/optomvse/venv/local/lib/python2.7/site-packages/werkzeug/local.py", line 306, in _get_current_object
return self.__local()
File "/home/xakep/Desktop/work/optomvse/venv/local/lib/python2.7/site-packages/flask/globals.py", line 37, in _lookup_req_object
raise RuntimeError(_request_ctx_err_msg)
RuntimeError: Working outside of request context.
This typically means that you attempted to use functionality that needed
an active HTTP request. Consult the documentation on testing for
information about how to avoid this problem.
Another thing i forgot to mention is that i also tried to use g instead of session , by just assigning the float(num) value to it so g.ruble = float(num), but inside my template if i typed {{g.ruble}} nothing get printed out .
If the value keeps changing store it somewhere (Redis/ any database) and when the request from the user comes just update the session data in the API call.
session['get_ruble'] = get_stored_value()
You can not update the session data asynchronously since you don't have the request context in the async task.
Just a suggestion:
If the value is so dynamic instead of storing it in the session, you can provide a separate API to fetch the latest data.
I'm using Django 1.6 and Django-ImageKit 3.2.1.
I'm trying to generate images asynchronously with ImageKit. Async image generation works locally but not on the production server.
I'm using Celery and I've tried both:
IMAGEKIT_DEFAULT_CACHEFILE_BACKEND = 'imagekit.cachefiles.backends.Async'
IMAGEKIT_DEFAULT_CACHEFILE_BACKEND = 'imagekit.cachefiles.backends.Celery'
Using the Simple backend (synchronous) instead of Async or Celery works fine on the production server. So I don't understand why the asynchronous backend gives me the following ImportError (pulled from the Celery log):
[2014-04-05 21:51:26,325: CRITICAL/MainProcess] Can't decode message body: DecodeError(ImportError('No module named s3utils',),) [type:u'application/x-python-serialize' encoding:u'binary' headers:{}]
body: '\x80\x02}q\x01(U\x07expiresq\x02NU\x03utcq\x03\x88U\x04argsq\x04cimagekit.cachefiles.backends\nCelery\nq\x05)\x81q\x06}bcimagekit.cachefiles\nImageCacheFile\nq\x07)\x81q\x08}q\t(U\x11cachefile_backendq\nh\x06U\x12ca$
Traceback (most recent call last):
File "/opt/python/run/venv/lib/python2.6/site-packages/kombu/messaging.py", line 585, in _receive_callback
decoded = None if on_m else message.decode()
File "/opt/python/run/venv/lib/python2.6/site-packages/kombu/message.py", line 142, in decode
self.content_encoding, accept=self.accept)
File "/opt/python/run/venv/lib/python2.6/site-packages/kombu/serialization.py", line 184, in loads
return decode(data)
File "/usr/lib64/python2.6/contextlib.py", line 34, in __exit__
self.gen.throw(type, value, traceback)
File "/opt/python/run/venv/lib/python2.6/site-packages/kombu/serialization.py", line 59, in _reraise_errors
reraise(wrapper, wrapper(exc), sys.exc_info()[2])
File "/opt/python/run/venv/lib/python2.6/site-packages/kombu/serialization.py", line 55, in _reraise_errors
yield
File "/opt/python/run/venv/lib/python2.6/site-packages/kombu/serialization.py", line 184, in loads
return decode(data)
File "/opt/python/run/venv/lib/python2.6/site-packages/kombu/serialization.py", line 64, in pickle_loads
return load(BytesIO(s))
DecodeError: No module named s3utils
s3utils is what defines my AWS S3 bucket paths. I'll post it if need be, but the strange thing I think is that the synchronous backend has no problem importing s3utils while the asynchronous does... and asynchronous does ONLY on the production server, not locally.
I'd be SO greatful for any help debugging this. I've been wrestling this for days. I'm still learning Django and python so I'm hoping this is a stupid mistake on my part. My Google-fu has failed me.
As I hinted at in my comment above, this kind of thing is usually caused by forgetting to restart the worker.
It's a common gotcha with Celery. The workers are a separate process from your web server so they have their own versions of your code loaded. And just like with your web server, if you make a change to your code, you need to reload so it sees the change. The web server talks to your worker not by directly running code, but by passing serialized messages via the broker, which will say something like "call the function do_something()". Then the worker will read that message and—and here's the tricky part—call its version of do_something(). So even if you restart your webserver (so that it has a new version of your code), if you forget to reload the worker (which is what actually calls the function), the old version of the function will be called. In other words, you need to restart the worker any time you make a change to your tasks.
You might want to check out the autoreload option for development. It could save you some headaches.
I have the following very simple app:
from lib.flask import Flask
from lib.flask_restful import Resource, Api
app = Flask(__name__)
api = Api(app)
class TestResource(Resource):
def get(self):
return {"a":"b","c":"d"}
api.add_resource(TestResource, "/")
When I run this, I get the following Exception:
Traceback (most recent call last):
File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/google/appengine/runtime/wsgi.py", line 266, in Handle
result = handler(dict(self._environ), self._StartResponse)
File "/Users/me/dev/project/src/main.py", line 22, in do_in_request
app(*args, **kwargs)
File "/Users/me/dev/project/src/lib/flask/app.py", line 1836, in __call__
return self.wsgi_app(environ, start_response)
File "/Users/me/dev/project/src/lib/flask/app.py", line 1820, in wsgi_app
response = self.make_response(self.handle_exception(e))
File "/Users/me/dev/project/src/lib/flask_restful/__init__.py", line 249, in error_router
if self._has_fr_route():
File "/Users/me/dev/project/src/lib/flask_restful/__init__.py", line 230, in _has_fr_route
if self._should_use_fr_error_handler():
File "/Users/me/dev/project/src/lib/flask_restful/__init__.py", line 211, in _should_use_fr_error_handler
adapter = self.app.create_url_adapter(request)
File "/Users/me/dev/project/src/lib/flask/app.py", line 1601, in create_url_adapter
return self.url_map.bind_to_environ(request.environ,
File "/Users/me/dev/project/src/lib/werkzeug/local.py", line 338, in __getattr__
return getattr(self._get_current_object(), name)
File "/Users/me/dev/project/src/lib/werkzeug/local.py", line 297, in _get_current_object
return self.__local()
File "/Users/me/dev/project/src/lib/flask/globals.py", line 20, in _lookup_req_object
raise RuntimeError('working outside of request context')
RuntimeError: working outside of request context
So I tried to put my entire app into what I thought would be the request context. In the code above, both the Flask object and the Api object are being instantiated once, and can be called by the server multiple times. From the traceback, it looks like the instantiation should happen within a request context, so I wrapped it like this:
def do_in_request(*args, **kwargs):
from lib.flask import Flask
from lib.flask_restful import Resource, Api
app = Flask(__name__)
api = Api(app)
class TestResource(Resource):
def get(self):
return {"a":"b","c":"d"}
api.add_resource(TestResource, "/")
app(*args, **kwargs)
app = do_in_request
That still raises the same error. What's going on, what do they mean by 'request context', and how do I fix this?
I started from scratch using the App Engine Flask Skeleton and added flask-restful as a dependency in requirements.txt and then just added more or less the code you have above and it worked without an issue. I added the repository to my github here if you want to use it - you can see the changes I made to the skeleton in this commit.
I'm not sure why your example isn't working, but one thing I noticed that could be causing issues is that you're doing from lib.flask .... It seems your third-party packages live in lib and you haven't necessarily "lifted" lib into your sys.path. The skeleton includes a vendoring library that makes sure that this is handled properly. It might be a potential source of the problem.
Either way, I hope the forked skeleton can help you get up and running.
I am trying to use a custom Transport class with xmlrpclib in Python but when I specify a custom Transport, I do get an exception at the first call:
File "/Users/sorins/dev/py/confluence/confluence/confluence.py", line 208, in __init__
self._token = self._server.confluence1.login(username, password)
File "/usr/local/Cellar/python/2.7.3/Frameworks/Python.framework/Versions/2.7/lib/python2.7/xmlrpclib.py", line 1224, in __call__
return self.__send(self.__name, args)
File "/usr/local/Cellar/python/2.7.3/Frameworks/Python.framework/Versions/2.7/lib/python2.7/xmlrpclib.py", line 1578, in __request
verbose=self.__verbose
TypeError: unbound method request() must be called with SafeTransport instance as first argument (got str instance instead)
Sample code:
#!/usr/bin/env python
from xmlrpclib import Transport
class MyTransport(Transport):
pass
server = xmlrpclib.ServerProxy('https://example.com/rpc/xmlrpc',allow_none=True,transport=MyTransport)
server.confluence1.login(username, password) # <-- exception
The original connection is made but the first call to RPC method will fail with the above error.
Removing the transport=MyTransport solves the problem.
Note: I tried the same with SafeTransport and same result.
I do need a custom transport in order to inject some headers. How do I fix this?
change to transport=MyTransport(), not the type, but an instance of this type.