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Python Programming Blueprints

You're reading from   Python Programming Blueprints Build nine projects by leveraging powerful frameworks such as Flask, Nameko, and Django

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Product type Paperback
Published in Feb 2018
Publisher Packt
ISBN-13 9781786468161
Length 456 pages
Edition 1st Edition
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Authors (3):
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Marcus Pennington Marcus Pennington
Author Profile Icon Marcus Pennington
Marcus Pennington
Pierluigi Riti Pierluigi Riti
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Pierluigi Riti
Daniel Furtado Daniel Furtado
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Daniel Furtado
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Toc

Table of Contents (11) Chapters Close

Preface 1. Implementing the Weather Application 2. Creating a Remote-Control Application with Spotify FREE CHAPTER 3. Casting Votes on Twitter 4. Exchange Rates and the Currency Conversion Tool 5. Building a Web Messenger with Microservices 6. Extending TempMessenger with a User Authentication Microservice 7. Online Video Game Store with Django 8. Order Microservice 9. Notification Serverless Application 10. Other Books You May Enjoy

Authenticating users


We can now look at how to authenticate users. This is a very simple process:

  1. Retrieve the user we want to authenticate from the database.
  2. Perform a bcrypt.checkpw giving it the attempted password and the password hash of the user.
  3. Raise an exception if the result is False.
  4. Return the user if it's True.

Retrieving users from the database

Starting with the first point, we will need to add a new dependency method, get, which returns the user, given the email, if it exists.

First, add a new exception class in users.py:

class UserNotFound(Exception): 
    pass 

This is what we will raise in the event of the user not being found. Now we will update our imports to include the following:

from sqlalchemy.orm.exc import NoResultFound 

NoResultFound, as the name implies, is raised by SQLAlchemy when a requested object is not found in the database. Now we can add a new method to our UserWrapper class:

def get(self, email): 
    query = self.session.query(User) # â‘  
 
    try: 
        user...
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