I have a simple app wrote with Flask Appbuilder, the view.py is as follows. It is part of exmaple in http://flask-appbuilder.readthedocs.io/en/latest/views.html with a little change in method1 where I replaced return 'Hello' with a function that I wish to find.
We can change the language in app (en,fr,ru,...) and translate it. Is there a function to get the current language? (Current_Language()).
from flask_appbuilder import AppBuilder, BaseView, expose, has_access, ModelView
from app import appbuilder, db
from flask import render_template, g
from flask_babel import Babel
from flask_babel import lazy_gettext as _
from flask_appbuilder.models.sqla.interface import SQLAInterface
class MyView(BaseView):
default_view = 'method1'
#expose('/method1/')
#has_access
def method1(self):
return Current_Language()
appbuilder.add_view(MyView, "Method1", category='My View')
The appbuilder instance has a bm attribute, which is an instance of the BabelManager class.
This class has a get_locale method that returns the current language your app is using.
class MyView(BaseView):
default_view = 'method1'
#expose('/method1/')
#has_access
def method1(self):
return appbuilder.bm.get_locale()
You can check the code for the BabelManager class on the project repository.
There is an ambiguity in your question. Do you mean the current server-side language or the client-side language.
The former:
import locale
locale.getlocale()
The latter:
from flask import request
request.headers.get('your-header-name')
The header you are interested in is Accept-Language. But there are caveats when it comes to inferring the client language that way. See https://www.w3.org/International/questions/qa-accept-lang-locales
Related
Suppose I have something like this in app/models.py:
from flask import current_app as app
from flask_sqlalchemy import SQLAlchemy
from sqlalchemy.sql import func
db = SQLAlchemy()
class LoginLink(db.Model):
...
expiration_date = db.Column(
db.DateTime(timezone=True), nullable=False,
server_default=func.now() + str(app.config["LOGIN_LINK_EXP_TIME"]) # Error here!!!
)
And this in app/__init__.py:
from flask import Flask
from config import CONFIG_OBJECT
def create_app(config_name):
app = Flask(__name__)
app.config.from_object(CONFIG_OBJECT[config_name])
from app.models import db
db.init_app(app)
db.create_all(app=app)
return app
Finally, this is my config.py:
from datetime import timedelta
CONFIG_OBJECT = {
"dev": "config.DevConfig",
"prod": "config.ProdConfig"
}
class Config:
...
class DevConfig(Config):
LOGIN_LINK_EXP_TIME = timedelta(seconds=30)
class ProdConfig(Config):
LOGIN_LINK_EXP_TIME = timedelta(minutes=30)
I tried to use app.app_context() everywhere (believe me) and I'm still getting this error:
RuntimeError: Working outside of application context.
I'm just trying to do the following: in a development environment I want the login links to expire in 30 seconds (for testing and demonstration purposes), but login links will last 30 minutes in a production environment.
How to accomplish this using different config environments?
Note: this is intended to be a generic question.
I think I had a misconception about application factories. We have the following from the Flask documentation:
The downside is that you cannot use the application object in the blueprints at import time. You can however use it from within a request.
Additionally:
It’s preferable to create your extensions and app factories so that the extension object does not initially get bound to the application.
What is in bold is what I was doing wrong: using the application object outside a request and bounding the extension to the application.
Therefore, I only see two solutions:
Use the app.config object (or dict) only within requests (the best IMHO).
Don't include configs that require to be used outside of requests in the app.config object (although this may complicate testing a bit).
This question is an extension on my previous one here. I was suggested to put more to explain the problem. As the heading says, I am trying to find a way to avoid importing the application factory (create_app function) into a module that needs application context and were "import current_app as app" is not sufficient.
My problem is I have a circular import problem due to this create_app function which I need to pass in order to get the app_context.
In my __ini__.py, I have this:
# application/__init__.py
from flask import Flask
from flask_sqlalchemy import SQLAlchemy
from flask_restful import Api
from application.resources.product import Product, Products
from application.resources.offer import Offer, Offers # HERE IS THE PROBLEM
api = Api()
db = SQLAlchemy()
api.add_resource(Product, "/product/<string:name>") # GET, POST, DELETE, PUT to my local database
api.add_resource(Products, "/products") # GET all products from my local database
api.add_resource(Offer, "/offer/<int:id>") # POST call to the external Offers API microservise
api.add_resource(Offers, "/offers") # GET all offers from my local database
def create_app(config_filename=None):
""" Initialize core application. """
app = Flask(__name__, instance_relative_config=False)
app.config.from_object("config.Config")
db.init_app(app)
api.init_app(app)
with app.app_context():
db.create_all()
return app
The problem is in this line:
from application.resources.offer import Offer, Offers # HERE IS THE PROBLEM
because in that module, I have:
#application/resources/offer.py
from flask_restful import Resource
from application.models.offer import OfferModel # IMPORTING OFFER MODEL
which in turn imports application/models/offer.py where I have the critical part:
#application/models/offer.py
import requests
# from flask import current_app as app
from application import create_app # THIS CAUSES THE CIRCULAR IMPORT ERROR
from sqlalchemy.exc import OperationalError
app = create_app() # I NEED TO CREATE THE APP IN ORDER TO GET THE APP CONTEXT BECASE IN THE CLASS I HAVE SOME FUNCTIONS THAT NEED IT
class OfferModel(db.Model):
""" Data model for offers. """
# some code to instantiate the class... + other methods..
# THIS IS ONE OF THE METHODS THAT NEED APP_CONTEXT OR ELSE IT WILL ERROR OUT
#classmethod
def update_offer_price(cls):
""" Call offers api to get new prices. This function will run in a separated thread in a scheduler. """
with app.app_context():
headers = {"Bearer": app.config["MS_API_ACCESS_TOKEN"]}
for offer_id in OfferModel.offer_ids:
offers_url = app.config["MS_API_OFFERS_BASE_URL"] + "/products/" + str(offer_id) + "/offers"
res = requests.get(offers_url, headers=headers).json()
for offer in res:
try:
OfferModel.query.filter_by(offer_id=offer["id"]).update(dict(price=offer["price"]))
db.session.commit()
except OperationalError:
print("Database does not exists.")
db.session.rollback()
I have tried to use from flask import current_app as app to get the context, it did not work. I don't know why it was not sufficient to pass current_app as app and get the context because it now forces me to pass the create_app application factory which causes the circular import problem.
Your update_offer_price method needs database interaction and an access to the configuration. It gets them from the application context but it works only if your Flask application is initialized. This method is run in a separate thread so you create the second instance of Flask application in this thread.
Alternative way is getting standalone database interaction and configuration access outside the application context.
Configuration
Configuration does not seem a problem as your application gets it from another module:
app.config.from_object("config.Config")
So you can directly import this object to your offer.py:
from config import Config
headers = {"Bearer": Config.MS_API_ACCESS_TOKEN}
Database access
To get standalone database access you need to define your models via SQLAlchemy instead of flask_sqlalchemy. It was already described in this answer but I post here the essentials. For your case it may look like this. Your base.py module:
from sqlalchemy import MetaData
from sqlalchemy.ext.declarative import declarative_base
metadata = MetaData()
Base = declarative_base(metadata=metadata)
And offer.py module:
import sqlalchemy as sa
from .base import Base
class OfferModel(Base):
id = sa.Column(sa.Integer, primary_key=True)
# Another declarations
The produced metadata object is used to initialize your flask_sqlalchemy object:
from flask_sqlalchemy import SQLAlchemy
from application.models.base import metadata
db = SQLAlchemy(metadata=metadata)
Your models can be queried outside the application context but you need to manually create database engine and sessions. For example:
from sqlalchemy import create_engine
from sqlalchemy.orm import Session
from config import Config
from application.models.offer import Offer
engine = create_engine(Config.YOUR_DATABASE_URL)
# It is recommended to create a single engine
# and use it afterwards to bind database sessions to.
# Perhaps `application.models.base` module
# is better to be used for this declaration.
def your_database_interaction():
session = Session(engine)
offers = session.query(Offer).all()
for offer in offers:
# Some update here
session.commit()
session.close()
Note that with this approach you can't use your models classes for queriing, I mean:
OfferModel.query.all() # Does not work
db.session.query(OfferModel).all() # Works
ok so this is how I solved it. I made a new file endpoints.py where I put all my Api resources
# application/endpoints.py
from application import api
from application.resources.product import Product, Products
from application.resources.offer import Offer, Offers
api.add_resource(Product, "/product/<string:name>") # GET, POST, DELETE, PUT - calls to local database
api.add_resource(Products, "/products") # GET all products from local database.
api.add_resource(Offer, "/offer/<int:id>") # POST call to the Offers API microservice.
api.add_resource(Offers, "/offers") # GET all offers from local database
Then in init.py I import it at the very bottom.
# aplication/__init__.py
from flask import Flask
from flask_restful import Api
from db import db
api = Api()
def create_app():
app = Flask(__name__, instance_relative_config=False)
app.config.from_object("config.Config")
db.init_app(app)
api.init_app(app)
with app.app_context():
from application import routes
db.create_all()
return app
from application import endpoints # importing here to avoid circular imports
It is not very pretty but it works.
spinngod.py - flask app starter code
from app import create_app
import sys
run_profile = str(sys.argv[1]) if len(sys.argv) >= 2 else 'development'
app = create_app(run_profile)
print("App Root Path:" + app.root_path)
if __name__ == '__main__':
print sys.path
app.run(debug=True, host='0.0.0.0')
app/init.py - creates flask app
def create_app(profile_name):
print "currently active profile:" + profile_name
app = Flask(__name__)
############# configurations ####################
app.config.from_object(config[profile_name])
configure_app(app)
configure_app_logger(app)
#################### blueprint registration and rest_plus namespace additions ###############
from api_1_0 import api as api_1_0_blueprint
from api_1_0.restplus import api_restplus
# ************************************************** #
api_restplus.init_app(api_1_0_blueprint)
api_restplus.add_namespace(application_namespace)
api_restplus.add_namespace(pipeline_template_namespace)
api_restplus.add_namespace(loadbalancer_namespace)
api_restplus.add_namespace(servergroup_namespace)
api_restplus.add_namespace(task_namespace)
# ************************************************** #
app.register_blueprint(api_1_0_blueprint)
##############################################################
return app
I want to access flask config variables defined in config.py in some other files which are outside application context. The app configuration depends on which profile it is started with (dev,stage or production) which is being passed from command line as an arg.
The only way that I can think of accessing config variables outside app context is to set profile (dev,stage or prod) as an environment variable and
then import directly from config file.
The second way that I tried was to move creation of flask app in app/init.py outside method.
This is how I am trying to access config variables in another class.
import requests
class Client(object):
def __init__(self):
from app import app
print "fjaijflkajsf" + app.config['SPINNAKER_BASE_URL']
pass
Is there a way better of doing this in flask ?
From the docs:
Rather than passing the application around to each function, the current_app and g proxies are accessed instead.
The Flask application object has attributes, such as config, that are useful to access within views and CLI commands. However, importing the app instance within the modules in your project is prone to circular import issues.
Flask solves this issue with the application context. Rather than referring to an app directly, you use the the current_app proxy, which points to the application handling the current activity.
You import current_app like this:
from flask import current_app
and then access the config or other attributes like this:
config = current_app.config
Example:
src/application.py (where config is set in the context)
create_app():
app = Flask('app')
app.config.from_object(some_class)
return app
src/module/another_module.py
from flask import current_app
def function_that_requires_config():
config = current_app.config
Alternative:
src/application.py (where config is set in the context)
APP = create_app(os.environ.get('FLASK_ENV'))
src/module/another_module.py
from src.application import APP
def function_that_requires_config():
config_value = APP.config.get(config_key, default_value)
Not sure if it is good to put it here as it may not respond to the question directly, but here is the cleanest way i've figured to use config values outside of requests, without having to pass config as a param.
The solution is actually pretty simple, juste consider the part of your code as a flask_extension.
my exemple will be the use of external api, with ROOT_URL in the config file, and i don't want to make api call from within my routes, so the api is in its own module.
in my create_app fuction:
from flask import Flask
from .api import api
from .configmodule import Config
from .model import db
def create_app(environment):
app = Flask(__name__)
app.config.from_object(Config.get_config(environment))
db.init_app(app)
api.init_app(app) # here i use api.init_app the same way i do for sqlalchemy
and in api/init.py
class Api:
def init_app(self, app):
self.config = app.config
api = Api()
and in any files in my api modude i can now write
from . import api
def foo():
print(api.config.get("API_ROOT_URL"))
this can even be improved if you feel the need to access some other global app vars from your module.
How to import a function and variable from app/__init__.py and app/blueprint/__init__.py , respectively, inside app/blueprint/views.py ?
app/__init__.py
def main():
<..>
app/blueprint/__init__.py
from flask import Blueprint
blueprint = Blueprint('blueprint', __name__, template_folder='templates')
app/blueprint/views.py
import blueprint
import main
from app.__init__ import *
from app.blueprint.__init__ import *
should import all the functions and variables from both files.
However, though I don't think init file is supposed to be used for this.
Below examples of Flask Blueprints I used my project, learnt structure from Udemy tutorial, I think the idea is generally the init files are used to make a Python directory into a package so you can import stuff within it. You'd probable better create new files with the functions (less often variables) you want to import, maybe experts will confirm, but I think generally you leave Python init files blank unless you really know what you're doing.
from flask import Flask, render_template
from Source.common.database import Database
from Source.models.users.views import user_blueprint
from Source.models.street_lists.views import street_list_blueprint
# from Source.models.street_reports.views import street_report_blueprint
__author__ = "Will Croxford, with some base structure elements based on Github: jslvtr, \
from a different tutorial web application for online price scraping"
app = Flask(__name__)
app.config.from_object('Source.config')
app.secret_key = "123"
app.register_blueprint(user_blueprint, url_prefix="/users")
app.register_blueprint(street_list_blueprint, url_prefix="/streetlists")
# app.register_blueprint(street_report_blueprint, url_prefix="/streetreports")
#app.before_first_request
def init_db():
Database.initialize()
#app.route('/')
def home():
return render_template('home.jinja2')
#app.route('/about_popup.jinja2')
def info_popup():
return render_template('about_popup.jinja2')
Flask Views file example:
# In this model, views.py files are the Flask Blueprint for this object.
# ie they describe what HTTP API endpoints are associated to objects of this class.
from flask import Blueprint, render_template, request, redirect, url_for
from Source.models.street_lists.street_list import StreetList
__author__ = 'jslvtr'
street_list_blueprint = Blueprint('street_lists', __name__)
#street_list_blueprint.route('/')
def index():
prop_query = StreetList.get_from_mongo(streetpart="bum")
return render_template('street_lists/street_list.jinja2', stores=prop_query)
You can look at pocoo.org flask doc examples, and search other SO questions for Flask blueprint template examples I think. Good luck!
I read the blog suggested by Will Croxford, and here's the solution to my problem:
app/blueprint/views.py
from app import main
from app.blueprint import blueprint
I'm using Flask with Blueprints to get a skeleton for my website and I'm having a problem using configuration classes deep in my application.
Here's some dummy code that explains how I've set everything up:
websiteconfig.py
class Config(object):
pass
class ProductionConfig(Config):
DEBUG = False
class DevelopmentConfig(Config):
DEBUG = True
website/__ init __.py:
# Some app code and config loading
app = Flask('website')
app.config.from_object('websiteconfig.DevelopmentConfig')
# Import some random blueprint
from website import users
app.register_blueprint(users.api)
# This works:
# print app.config['DEBUG']
website/users/__ init __.py:
from flask import Blueprint
from website.users.models import test
api = Blueprint('users', __name__, url_prefix='/users')
# This works:
# print api.config['DEBUG']
# From models
print test()
website/users/models.py:
# How can I reach the config variables here?
def test():
# I want config['DEBUG'] here
How can I reach the configuration variables stored in the class I load in app.py deep inside the users package?
Is a circular import like from website import app (inside models.py) an accepted solution?
If not, is there some simple solution I've missed?
I believe you can use flask's current_app idiom for that.
http://flask.pocoo.org/docs/api/#flask.current_app
from flask import current_app
def test():
return current_app.config.get('some_config_value')