烧瓶-邮件-异步发送电子邮件，基于烧瓶-库克

Question

我的烧瓶项目是基于烧瓶-炊具的，我需要异步发送电子邮件。

发送电子邮件的函数是由米格尔教程配置的，并且同步发送很好，但我不知道如何修改它以异步发送。

我的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

我的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)

view.py中的路由

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

应用程序在我的本地主机中运行，它以命令开头

python manage.py server

当我调用函数发送邮件时，控制台中的输出是：

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.

谢谢你的回答。

Answer 1

好的，我为我的问题找到了解决方案--我在这里为其他开发人员张贴了它：

我用代码创建了文件: email.py：

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

我的view.py：

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

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

当我打电话给http://localhost:5000/mailer时，它开始倒计时，几秒钟后，邮件就被发送了。

Answer 2

将电子邮件发送功能移动到后台线程：

from threading import Thread

def send_async_email(app,msg):
       with current_app.app_context():
               mail.send(msg)

def send_email(to, subject, template, **kwargs):
       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

Answer 3

您可以将app = Flask(__name__)移出应用程序工厂，并将其放置在模块级别。这允许您将带有其应用程序上下文的应用实例传递到您的线程中，以便发送电子邮件。您可能需要更改其他领域的一些导入，以防止循环依赖，但这应该不会太糟糕。

这里是一个使用如何做到这一点的例子的烧杯邮件和烧瓶-RESTful。它还展示了如何使用pytest来测试这一点。

from flask import Flask

from .extensions import mail
from .endpoints import register_endpoints
from .settings import ProdConfig

# app context needs to be accessible at the module level
# for the send_message.send_
app = Flask(__name__)


def create_app(config=ProdConfig):
    """ configures and returns the the flask app """
    app.config.from_object(config)

    register_extensions()
    register_endpoints(app)

    return app


def register_extensions():
    """ connects flask extensions to the app """
    mail.init_app(app)

在你发送电子邮件的模块里，你会看到这样的东西：

from flask_mail import Message

from app import app
from app import mail
from utils.decorators import async_task


def send_email(subject, sender, recipients, text_body, html_body=None, **kwargs):
    app.logger.info("send_email(subject='{subject}', recipients=['{recp}'], text_body='{txt}')".format(sender=sender, subject=subject, recp=recipients, txt=text_body))
    msg = Message(subject, sender=sender, recipients=recipients, **kwargs)
    msg.body = text_body
    msg.html = html_body

    app.logger.info("Message(to=[{m.recipients}], from='{m.sender}')".format(m=msg))
    _send_async_email(app, msg)


@async_task
def _send_async_email(flask_app, msg):
    """ Sends an send_email asynchronously
    Args:
        flask_app (flask.Flask): Current flask instance
        msg (Message): Message to send
    Returns:
        None
    """
    with flask_app.app_context():
        mail.send(msg)

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(2019年评论)

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注意:我在几年前发布了这篇文章，我觉得在应用工厂之外实例化烧瓶对象并不理想。send_email函数需要一个烧瓶实例才能工作，但是您可以在该函数中实例化一个新的烧瓶应用程序(不要忘记您的配置)。

我猜想current_app可能也能工作，但我觉得这可能会产生副作用，因为它需要创建一个新的应用程序上下文--在当前的应用程序上下文中，似乎是错误的，但可能有效。

一个很好的选择是:查看芹菜并使用RabbitMQ作为后端。

对于较大的应用程序或卷，您可能会考虑通过message (如RabbitMQ )将电子邮件发送到另一个应用程序。查看事件驱动的设计模式。如果您有需要邮寄服务的多个应用程序，这可能是很有吸引力的。如果您的服务需要支持审计日志、交付恢复等，这可能会很好。