使用 Flask 在后台任务中发送批量电子邮件

Question

我正在使用 Flask Mail 从我的 Flask 应用程序发送电子邮件。从主线程使用它没问题。但是，我有一条可以发送大量电子邮件的路由（我认为足以超过 HTTP 超时），我想快速 return 回复并运行在后台发送邮件.

我尝试了以下解决方案：

from concurrent.futures import ThreadPoolExecutor

executor = ThreadPoolExecutor(max_workers=1)
mailer = Mail(app) #Flask Mail Mailer

@app.route("/admin/sendmails")
def sendmails():

  #
  # Code to get recipients from DB here
  # 


  executor.submit(send_links,recipients,mailer)
  return "Mail sending began"

这里是 send_mails 函数的代码：

  def send_links(recipients,mailing=None):
    subject = "My subject"
    if mailing == None : return logger.warning("No mailing available : Login links could not be sent")
    with mailing.connect() as conn:
        for [recipient,token,fullname] in recipients:
            try:
                raw_body = render_template("mails/login.txt",token=token, fullname=fullname)
                html_body = render_template("mails/login.html",token=token, fullname=fullname)
                msg = Message(subject,
                            recipients=[recipient])
                msg.body = raw_body
                msg.html = html_body
                msg.attach('logo.png','image/png',open(os.path.join(os.path.dirname(os.path.abspath(__file__)),'static/image/logo.png'), 'rb').read(), 'inline', [['Content-ID', '<LOGO>']])
                conn.send(msg)
            except Exception as e:
                logger.warning("Impossible to send login token \"{}\" to {}".format(token, fullname))
                logger.warning(traceback.format_exc())
    return True

但是 send_links 函数在 Flask 上下文中使用 render_template（我猜邮件程序可能也使用它）所以我得到以下错误...

Traceback (most recent call last):
  File "/var/www/rbt-rdd/server/utils.py", line 114, in send_links
    raw_body = render_template("mails/login.txt",token=token, fullname=fullname)
  File "/var/www/rbt-rdd/venv/lib/python3.9/site-packages/flask/templating.py", line 146, in render_template
    ctx.app.update_template_context(context)
AttributeError: 'NoneType' object has no attribute 'app'

你知道如何解决这个问题吗？

Answer 1

手动推送上下文：

def send_links(recipients, mailing=None):
    # ...                    # -
    with app.app_context():  # +
        ...                  # +

参考：https://flask.palletsprojects.com/en/2.0.x/appcontext/#manually-push-a-context

您可以将其实现为装饰器，尤其是当您有许多这样的功能时：

from functools import wraps

def with_app_context(func):
    @wraps(func)
    def _func(*args, **kwargs):
        with app.app_context():
            return func(*args, **kwargs)
    return _func

用法：

@with_app_context  # +
def send_links(recipients, mailing=None):
    ...

使用 Flask 在后台任务中发送批量电子邮件

Send bulk emails in background task with Flask

python

multithreading

flask

web

flask-mail