Develop Reference

Apscheduler running jobs concurrently in Flask

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

RuntimeError: Working outside of application context. in my flask app

I'm trying to schedule sending email from my flask application with this function :
from apscheduler.scheduler import Scheduler
scheduler = Scheduler()
scheduler.start()
def email_job_scheduling():
to="abdellah.ala#gmail.com"
subject="summary projects"
message="your summary projects"
send_email(to,subject,message)
scheduler.add_cron_job(email_job_scheduling, day_of_week='tue', hour=12, minute=55)
this is how i declare app in my file init.py, is there any relationship or must i add schedule function in this file.
login_manager = LoginManager()
db = SQLAlchemy()
mail = Mail()
def create_app(config_name):
app = Flask(__name__, instance_relative_config=True)
app.config.from_object(app_config[config_name])
app.config.from_pyfile('config.py')
app.permanent_session_lifetime = timedelta(minutes=10)
db.init_app(app)
mail.init_app(app)
login_manager.init_app(app)
return app
but I receive this error,
Debug mode: off * Running on http://127.0.0.1:5000/ (Press CTRL+C to
quit) Job "email_job_scheduling (trigger: cron[day_of_week='wed',
hour='9', minute='57'], next run at: 2019-12-11 09:57:00)" raised an
exception Traceback (most recent call last): File
"/home/abdellah/Documents/venv/lib64/python3.6/site-packages/apscheduler/scheduler.py",
line 512, in _run_job
retval = job.func(*job.args, **job.kwargs) File "/home/abdellah/Documents/SUPPORT-STS/project/app/admin/views.py",
line 29, in email_job_scheduling
send_email(to,subject,message) File "/home/abdellah/Documents/SUPPORT-STS/project/app/emails.py",
line 11, in send_email
mail.send(msg) File "/home/abdellah/Documents/venv/lib64/python3.6/site-packages/flask_mail.py",
line 491, in send
with self.connect() as connection: File "/home/abdellah/Documents/venv/lib64/python3.6/site-packages/flask_mail.py",
line 508, in connect
return Connection(app.extensions['mail']) File "/home/abdellah/Documents/venv/lib64/python3.6/site-packages/werkzeug/local.py",
line 348, in getattr
return getattr(self._get_current_object(), name) File "/home/abdellah/Documents/venv/lib64/python3.6/site-packages/werkzeug/local.py",
line 307, in _get_current_object
return self.__local() File "/home/abdellah/Documents/venv/lib64/python3.6/site-packages/flask/globals.py",
line 52, in _find_app
raise RuntimeError(_app_ctx_err_msg) RuntimeError: Working outside of application context.
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.

Yes if you have not specified an application context you should create it.
This is because it is necessary to define all the necessary resources within the Flask application.
The documentation explains perfectly in which cases and how you should use a context application in Flask.
https://flask.palletsprojects.com/en/1.0.x/appcontext/
If you post more code I could be more helpful.
I will try to find a solution by the way:
from flask import g
def email_job_scheduling():
a = "abdellah.ala#gmail.com"
subject = "summary projects"
message = "your summary projects"
send_email (to, subject, message)
def get_scheduler():
if "scheduler" is not in g:
g.scheduler = Scheduler()
g.scheduler.start()
returns g.scheduler
with app.app_context(): #add the necessary resources
scheduler = get_scheduler()
#add another code if you need to set another resource
#This piece of code I think is in the main
scheduler.add_cron_job (email_job_scheduling, day_of_week = 'tue', now = 12, minute = 55)

Flask how to get config element from another file (for example: helper.py)

Good day.
I have one question. How to access a configuration item from another .py file
For example.
app/__init__.py
def create_app(config=None):
app = Flask(__name__, instance_relative_config=True)
app._static_folder = './static'
app.config.from_pyfile('flask.cfg')
app.app_context().push()
return app
wsgi.py
from app import create_app
from werkzeug.debug import DebuggedApplication
if __name__ == "__main__":
app = create_app()
application = DebuggedApplication(app, evalex=True)
app.logger.info("Debug status is: " + str(app.config['DEBUG']))
app.run(use_reloader=True, debug=True)
app/core/helper.py
from flask import current_app as app
def get_dir():
return app.config["PATH_CACHE_DIR"]
Try to call method app/core/cached.py
from flask_caching import Cache
from flask import current_app as app
from app.core.helper import get_dir
print get_dir()
So, i receive the following error
Traceback (most recent call last):
File "/home/stanislav/Python/mbgp/wsgi.py", line 1, in <module>
from app import create_app
File "/home/stanislav/Python/mbgp/app/__init__.py", line 4, in <module>
from app.core.cached import cache
File "/home/stanislav/Python/mbgp/app/core/cached.py", line 5, in <module>
print get_dir()
File "/home/stanislav/Python/mbgp/app/core/helper.py", line 14, in get_dir
return app.config["PATH_CACHE_DIR"]
File "/usr/local/lib/python2.7/dist-packages/werkzeug/local.py", line 347, in __getattr__
return getattr(self._get_current_object(), name)
File "/usr/local/lib/python2.7/dist-packages/werkzeug/local.py", line 306, in _get_current_object
return self.__local()
File "/usr/local/lib/python2.7/dist-packages/flask/globals.py", line 51, in _find_app
raise RuntimeError(_app_ctx_err_msg)
RuntimeError: Working outside of application context.
This typically means that you attempted to use functionality that needed
to interface with the current applicat`enter code here`ion object in some way. To solve
this, set up an application context with app.app_context(). See the
documentation for more information.
Please tell me how to fix this, thank you very much.

RuntimeError when running a simple flask_restful app on Google App Engine

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.

Flask-Assets and Flask-Testing throws RegisterError: Another bundle is already registered

I have my Flask app which uses Flask-Assets and while trying to run the unittest cases, except the first testcase, others fails with the following RegisterError.
======================================================================
ERROR: test_login_page (tests.test_auth.AuthTestCase)
----------------------------------------------------------------------
Traceback (most recent call last):
File "/Users/cnu/env/flenv/lib/python2.7/site-packages/nose/case.py", line 133, in run
self.runTest(result)
File "/Users/cnu/env/flenv/lib/python2.7/site-packages/nose/case.py", line 151, in runTest
test(result)
File "/Users/cnu/env/flenv/lib/python2.7/site-packages/flask_testing.py", line 72, in __call__
self._pre_setup()
File "/Users/cnu/env/flenv/lib/python2.7/site-packages/flask_testing.py", line 80, in _pre_setup
self.app = self.create_app()
File "/Users/cnu/Projects/Bookworm/App/tests/test_auth.py", line 8, in create_app
return create_app('testing.cfg')
File "/Users/cnu/Projects/Bookworm/App/bookworm/__init__.py", line 118, in create_app
configure_extensions(app)
File "/Users/cnu/Projects/Bookworm/App/bookworm/__init__.py", line 106, in configure_extensions
assets.register('js_all', js)
File "/Users/cnu/env/flenv/src/webassets/src/webassets/env.py", line 374, in register
'as "%s": %s' % (name, self._named_bundles[name]))
RegisterError: Another bundle is already registered as "js_all": <Bundle output=assets/packed.js, filters=[<webassets.filter.jsmin.JSMin object at 0x10fa8af90>], contents=('js/app.js',)>
My understanding of why this happens in before the first testcase is run, create_app creates an instance of app and this is maintained for all other testcases.
I tried del(app) in the teardown method, but doesn't help.
Is there some way to fix it?

You probably have a global object for the assets environment, which you have declared as such :
in file app/extensions.py:
from flask.ext.assets import Environment
assets = Environment()
Then, somewhere in your create_app method, you should init the environment:
in file app/__init__.py:
from .extensions import assets
def create_app():
app = Flask(__name__)
...
assets.init_app(app)
...
return app
The thing is that when you initialize your environment with you app, the registered bundles aren't cleared. So you you should do it manually as such in your TestCase:
in file tests/__init__.py
from app import create_app
from app.extensions import assets
class TestCase(Base):
def create_app(self):
assets._named_bundles = {} # Clear the bundle list
return create_app(self)
Hope this helps,
Cheers