Flask-Mail - Sending email asynchronously, based on Flask-Cookiecutter

Question

My flask project is based on Flask-Cookiecutter and I need to send emails asynchronously.

Function for sending email was configured by Miguel’s Tutorial and sending synchronously works fine, but i don’t know, how I can modify it for sending asynchronously.

My app.py

def create_app(config_object=ProdConfig):
    app = Flask(__name__)
    app.config.from_object(config_object)
    register_extensions(app)
    register_blueprints(app)
    register_errorhandlers(app)
    return app

def register_extensions(app):
    assets.init_app(app)
    bcrypt.init_app(app)
    cache.init_app(app)
    db.init_app(app)
    login_manager.init_app(app)
    debug_toolbar.init_app(app)
    migrate.init_app(app, db)
    mail.init_app(app)
    return None

my view.py

from flask import current_app

@async
def send_async_email(current_app, msg):
    with current_app.app_context():
        print('##### spustam async')
        mail.send(msg)


# Function for sending emails
def send_email(to, subject, template, **kwargs):
    msg = Message(subject, recipients=[to])
    msg.html = render_template('emails/' + template, **kwargs)
    send_async_email(current_app, msg)

route in view.py

@blueprint.route('/mailer', methods=['GET', 'POST'])
def mailer():
    user = current_user.full_name
    send_email(('[email protected]'),
               'New mail', 'test.html',
               user=user)
    return "Mail has been send."

Application run in my localhost and it's starting with command:

python manage.py server

When i call function for sending mail, output in console is:

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 a way.  To solve
this set up an application context with app.app_context().  See the
documentation for more information.

Thanks for any answer.

Answer 1

Okay, i found solution for my question i posting it here for others developers:

I create file: email.py with code:

from threading import Thread
from flask import current_app, render_template
from flask_mail import Message
from .extensions import mail
from time import sleep    

def send_async_email(app, msg):
    with app.app_context():
        # block only for testing parallel thread
        for i in range(10, -1, -1):
            sleep(2)
            print('time:', i)
        print('====> sending async')
        mail.send(msg)

def send_email(to, subject, template, **kwargs):
    app = current_app._get_current_object()
    msg = Message(subject, recipients=[to])
    msg.html = render_template('emails/' + template, **kwargs)
    thr = Thread(target=send_async_email, args=[app, msg])
    thr.start()
    return thr

my view.py:

...
from app.email import send_email
...

@blueprint.route('/mailer', methods=['GET', 'POST'])
def mailer():
    user = current_user.full_name
    send_email(('[email protected]'),
               'New mail', 'test.html',
               user=user)
    return "Mail has been send."

And when i call http://localhost:5000/mailer it starts countdown and after few seconds is mail sent.