Creating a reminder app

Let's get into some real-world examples in Celery. Suppose another page on our site now requires a reminder feature. Users can create reminders that will send an e-mail to a specified location at the time specified. We will need a model, a task, and a way to call our task automatically every time a model is created.

Let's start with the following basic SQLAlchemy model:

class Reminder(db.Model):
    id = db.Column(db.Integer(), primary_key=True)
    date = db.Column(db.DateTime())
    email = db.Column(db.String())
    text = db.Column(db.Text())

    def __repr__(self):
        return "<Reminder '{}'>".format(self.text[:20])

Now we need a task that will send an e-mail to the location in the model. In our tasks.py file, add the following task:

import smtplib
from email.mime.text import MIMEText

@celery.task(
    bind=True,
    ignore_result=True,
    default_retry_delay=300,
    max_retries=5
)
def remind(self, pk):
    reminder = Reminder.query.get(pk)
    msg...