《Flask Web Development》第6章-邮件

当某些事件被触发，应用程序通常需要通过邮件方式通知用户。Python的原生包smtplib能够被用于发送邮件，但是Flask的扩展Flask-Mail更好包装了smtplib能够方便地和Flask进行交互。

Flask-Mail提供的邮件支持

Email Support with Flask-Mail

• 安装

(venv) $ pip install flask-mail

• 配置server等参数

app.config['MAIL_SERVER'] = 'smtp.googlemail.com'
app.config['MAIL_PORT'] = 587
app.config['MAIL_USE_TLS'] = True
app.config['MAIL_USERNAME'] = os.environ.get('MAIL_USERNAME')
app.config['MAIL_PASSWORD'] = os.environ.get('MAIL_PASSWORD')

• 配置所用到的用户名和密码

(venv) $ export MAIL_USERNAME=<Gmail username>
(venv) $ export MAIL_PASSWORD=<Gmail password>

通过Python Shell发送邮件

Sending Email from the Python Shell

为了测试上述配置是否有用，可以在shell中测试是否有用：

(venv) $ python hello.py shell
>>> from flask.ext.mail import Message
>>> from index import mail
>>> msg = Message('test subject', sender='you@example.com', 
... recipients=['you@example.com'])
>>> msg.body = 'text body'
>>> msg.html = '<b>HTML</b> body'
>>> with app.app_context():
... mail.send(msg)
...

邮件和应用程序集成

Integrating Emails with the Application

配置和定义send_mail：

app.config['FLASKY_MAIL_SUBJECT_PREFIX'] = '[Flasky]'
app.config['FLASKY_MAIL_SENDER'] = 'Flasky Admin flasky@example.com'

def send_email(to, subject, template, **kwargs):
    msg = Message(app.config['FLASKY_MAIL_SUBJECT_PREFIX'] + subject,
                  sender=app.config['FLASKY_MAIL_SENDER'], recipients=[to])
    msg.body = render_template(template + '.txt', **kwargs)
    msg.html = render_template(template + '.html', **kwargs)
    mail.send(msg)

相应地改写view Function：

app.config['FLASKY_ADMIN'] = os.environ.get('FLASKY_ADMIN')
#...
@app.route('/', methods=['GET', 'POST'])
def index():
    form = NameForm()
    if form.validate_on_submit():
        user = User.query.filter_by(username=form.name.data).first()
        if user is None:
            user = User(username=form.name.data)
            db.session.add(user)
            session['known'] = False
            if app.config['FLASKY_ADMIN']:
                send_email(app.config['FLASKY_ADMIN'], 'New User',
                           'mail/new_user', user=user)
        else:
            session['known'] = True

        session['name'] = form.name.data
        form.name.data = ''

        return redirect(url_for('index'))
    return render_template('index.html', form=form, name=session.get('name'), known=session.get('known', False))

配置系统环境变量：

(venv) $ export FLASKY_ADMIN=<your-email-address>

发送异步邮件

Sending Asynchronous Email

发送邮件的瞬间，页面是没有响应的，为了jiejeu这个问题，邮件发送可以交给后台线程来做：

from threading import Thread

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

def send_email(to, subject, template, **kwargs):
    msg = Message(app.config['FLASKY_MAIL_SUBJECT_PREFIX'] + subject,
                  sender=app.config['FLASKY_MAIL_SENDER'], recipients=[to])
    msg.body = render_template(template + '.txt', **kwargs)
    msg.html = render_template(template + '.html', **kwargs)
    thr = Thread(target=send_async_email, args=[app, msg])
    thr.start()
    return thr