access app config variables in Flask app

Question

I have a flask app that looks like this:

myapp
-- application.py
-- models.py
-- queries.py
-- routes.py
-- settings.py

application.py looks like this:

from flask import Flask
from myapp import routes

def create_app(config_object):

    app = Flask(__name__)
    app.config.from_object(config_object)

    app.register_blueprint(routes.main)

    return app

queries.py looks like this

from myapp.models import User

class QueryConnection(DATABASE_URI):
    self.engine = create_engine(DATABASE_URI)
    self.session = sessionmaker(bind=self.engine)
    self.Session = self.session()

    def get_all_users(self):
        return self.Session.query(User).all()

routes.py looks like this:

from flask import current_app, Blueprint, render_template
from myapp import queries
main = Blueprint('main', __name__, url_prefix='/')

query_connection = queries.QueryConnection(current_app.config['DATABASE_URI'])

@main.route("/")
def index():
    return render_template('index.jinja2', list=query_connection.get_all_users())

models.py looks like this:

from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import Column, Integer, String

Base = declarative_base()

class User(Base):
    __tablename__ = 'users'

    id           = Column(Integer, primary_key=True)
    name         = Column(String)

I want to get the current_app.config['DATABASE_URI'] in routes.py so I can query the database but I don't know how to pass the app context from application.py to queries.py. I tried using this in application.py

with app.app_context():
    app.register_blueprint(main)

But I get the error "working outside of application context". Anything else gives the same error.

I want to encapsulate the queries in its own class so that I can pass the database uri in different contexts like in tests.

Answer 1

you need to import the file, from where you are calling the create_app method. My guess is that it is the application.py.

--- D_file.py

app = create_app(your_config)

--- queries.py

from D_file import app

DB_URI = app.config['DATABASE_URI']