Adventures in Machine Learning

Mastering Flask Email Confirmation: A Comprehensive Guide

Flask Email Confirmation

Flask email confirmation is a vital feature necessary for any web application that requires user registration. It helps to verify the authenticity of users’ email addresses, preventing fake or invalid user accounts from registering on a website.

Flask boilerplate codes for user registration come in handy when developing applications. In this article, we will explore some of the essential aspects of flask email confirmation, including the user registration process, email confirmation workflow, and limitations that come with Flask-User and Flask-Security extensions.

Implementing User Registration with Flask Boilerplate

Flask boilerplate codes are essential for building a web application with user registration features. It comes with pre-built functionalities that developers can leverage when developing their applications.

One of the core functionalities of Flask boilerplate is user registration. Flask boilerplate codes usually provide a user-friendly registration form where users can input their details and register to use the web application.

The registration form would include the user’s name, email address, and password. The form may also have optional fields such as the user’s phone number, address, and profile picture.

When the user submits the registration form, their details are stored in a database, and at this stage, the user becomes registered.

Email Confirmation Workflow

The email confirmation workflow is an essential process in the user registration cycle. After a user submits their registration form, Flask sends a confirmation email to the user’s email address.

The confirmation email includes a link to confirm the user’s email address. The link contains a unique token that Flask generates as a way of ensuring that the user did not get a generic email address.

Flask also sets the user’s confirmed attribute to false at this stage, indicating that the user account is yet to be verified.

When the user clicks on the link to confirm their email address, Flask routes the user to a confirmation page.

Flask validates the unique token included in the confirmation link, sets the user’s confirmed attribute to true, and redirects the user to the homepage of the web application. The user can now log in to the application and access its features.

Flask-User and Flask-Security Limitations

Flask-User and Flask-Security are widely-used Flask extensions for implementing authentication and security features in Flask applications. These extensions come in handy when developing applications with user registration, login, and session management functionalities.

They also provide built-in methods for dealing with password hashing and password reset functionalities. However, Flask-User and Flask-Security have their limitations.

For instance, they only work with specific databases like SQLite, PostgreSQL, and MySQL, amongst others. They do not support databases like MongoDB, which are popular in the software development community.

Also, Flask-User and Flask-Security do not work well with complex application architectures that involve several databases and microservices.

Updating the Register View Function

The register view function is a Flask function that maps to the user registration page of the web application. Flask developers can update the register view function to suit the specific requirements of their applications.

For example, they can add custom fields to the registration form, integrate third-party email services, and customize the response message for successful or failed registration attempts.

Flask Login

Flask-Login is a Flask extension that simplifies session management in Flask applications. It provides built-in handlers for login, logout, and user sessions.

Flask-Login also includes decorators for implementing user authentication and authorization functionalities. It stores user information in a secure session cookie, making it easier for developers to manage user sessions and access control.

Flask-SQLAlchemy

Flask-SQLAlchemy is a Flask extension that integrates the popular SQLAlchemy database toolkit into Flask applications. SQLAlchemy is an object-relational mapper that provides a high-level interface for interacting with databases, including PostgreSQL, MySQL, SQLite, and Oracle.

Flask-SQLAlchemy provides a declarative base class for mapping application classes to database tables, making it easier for Flask developers to work with databases.

Conclusion

In summary, Flask email confirmation is essential for ensuring that users’ email addresses are authentic and preventing fake accounts from accessing web applications. Flask boilerplate provides pre-built codes that Flask developers can use to implement user registration quickly.

Flask-User and Flask-Security provide standard functionalities for authentication and security but have limitations that developers should be aware of. Updating the register view function, implementing Flask-Login, and using

Flask-SQLAlchemy can enhance the security and user experience of Flask applications.

Add Email Confirmation

Email confirmation is an essential feature of any Flask application that requires user registration. It helps to ensure that the user’s email address is valid, and the user has access to the email address provided.

In this section, we will explore how to add email confirmation to a Flask application. We will cover generating a confirmation token, the confirm email view function, and sending emails with Flask-Mail.

Generate Confirmation Token

To add email confirmation to a Flask application, we need to generate a unique URL or confirmation token that we can send to the user’s email address. Flask provides the itsdangerous package, which we can use to generate secure tokens.

The package can sign the token with a secret key, ensuring that no one can manipulate it. To generate the token, we can use the following code:

“`

from itsdangerous import URLSafeTimedSerializer

from flask import current_app

def generate_confirmation_token(email):

serializer = URLSafeTimedSerializer(current_app.config[‘SECRET_KEY’])

return serializer.dumps(email, salt=current_app.config[‘SECURITY_PASSWORD_SALT’])

“`

In the code above, we import the URLSafeTimedSerializer class from the itsdangerous package and the current_app object from Flask. We then define the generate_confirmation_token function that takes an email address as an argument.

Inside the function, we create an instance of the serializer using the secret key defined in the application’s configuration. We then use the dumps method of the serializer to encode the email address into a string and generate a unique token.

We also add a salt value to the token generated using the SECURITY_PASSWORD_SALT configuration value.

Confirm Email View Function

After generating the confirmation token, we need to create a view function that handles the confirmation process. The confirm_email view function should verify the token’s authenticity, set the email_confirmed attribute, and redirect the user to the login page.

Here is an example of a confirm_email view function:

“`

from itsdangerous import URLSafeTimedSerializer

from flask import current_app, render_template, redirect, url_for

@app.route(‘/confirm/‘)

def confirm_email(confirmation_token):

try:

serializer = URLSafeTimedSerializer(current_app.config[‘SECRET_KEY’])

email = serializer.loads(

confirmation_token,

salt=current_app.config[‘SECURITY_PASSWORD_SALT’],

max_age=86400

)

except:

return render_template(‘invalid_token.html’)

user = User.query.filter_by(email=email).first_or_404()

if user.email_confirmed:

return redirect(url_for(‘login’))

user.email_confirmed = True

db.session.add(user)

db.session.commit()

return redirect(url_for(‘login’))

“`

In the code above, we define the confirm_email view function that takes a confirmation_token as an argument. Inside the function, we create a serializer instance and use the loads method to decode the token and retrieve the email address.

If there is an issue with the token’s authenticity, we render an invalid_token.html template that informs the user of the problem. Otherwise, we use the email address to fetch the user from the database.

If the user’s email address has already been confirmed, we redirect the user to the login page. Otherwise, we set the user’s email_confirmed attribute to True, add the user to the database session, commit the changes, and redirect the user to the login page.

Sending Emails with Flask-Mail

To send confirmation emails, we can use the Flask-Mail extension, which provides an easy way to send emails from a Flask application. We need to configure Flask-Mail before using it to send emails.

Here is an example of how to configure Flask-Mail:

“`

from flask_mail import Mail

app = Flask(__name__)

mail = Mail(app)

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’)

“`

In the code above, we import the Mail class from Flask-Mail and create an instance of it, passing the Flask application instance as a parameter. We then set the configuration values for the email server, port, TLS, username, and password.

To send an email, we can use the following code:

“`

from flask_mail import Message

from flask import url_for

def send_email(to, subject, template):

msg = Message(

subject,

recipients=[to],

html=template,

sender=current_app.config[‘MAIL_USERNAME’]

)

mail.send(msg)

“`

In the code above, we define the send_email function, which takes the recipient’s email address, email subject, and email template as parameters. We create a Message instance and set the recipients, subject, HTML body, and sender email address fields.

We then send the email using the Mail object’s send method.

Handle Permissions

Handling permissions in a Flask application is essential for restricting user access to particular parts of the application, especially for unconfirmed users. In this section, we will explore how to handle permissions by adding an unconfirmed route, adding an unconfirmed.html template, and creating a decorator function using Flask-Login.

Adding Unconfirmed Route

To handle permissions for unconfirmed users, we need to add an unconfirmed route that allows them to confirm their email addresses and gain full access to the application. Here is an example of an unconfirmed route:

“`

from flask_login import current_user

@app.route(‘/unconfirmed’)

def unconfirmed():

if current_user.is_anonymous or current_user.email_confirmed:

return redirect(url_for(‘index’))

return render_template(‘unconfirmed.html’)

“`

In the code above, we import the current_user object from Flask-Login and define the unconfirmed route that maps to the /unconfirmed URL. If the user is anonymous or has already confirmed their email address, we redirect them to the index page.

Otherwise, we render the unconfirmed.html template that informs the user that they need to confirm their email address before gaining full access to the application. Adding Unconfirmed.html Template

The unconfirmed.html template is a page that informs the user that they need to confirm their email address before they can access all of the application’s features.

Here is an example of an unconfirmed.html template:

“`

{% extends “base.html” %}

{% block content %}

Unconfirmed Email Address

Please check your email inbox and click on the confirmation link to confirm your email address. If you did not receive the confirmation email, click here to resend it.

{% endblock %}

“`

In the code above, we extend the base.html template and define the content block. We then add a header and a paragraph that inform the user that they need to confirm their email address and provide a link to resend the confirmation email.

Creating a Decorator

To handle permissions for unconfirmed users, we need to create a decorator function that restricts access to pages that require user authentication but not email confirmation. We can use the @login_required decorator function from Flask-Login and create a custom decorator function that checks whether the user has confirmed their email address.

Here is an example of a custom decorator function:

“`

from functools import wraps

from flask import flash, redirect, url_for

from flask_login import current_user

def confirmed_required(func):

@wraps(func)

def decorated_function(*args, **kwargs):

if current_user.is_authenticated and not current_user.email_confirmed:

flash(‘Please confirm your email address first.’, ‘warning’)

return redirect(url_for(‘unconfirmed’))

elif current_user.is_authenticated and current_user.email_confirmed:

return func(*args, **kwargs)

else:

return redirect(url_for(‘login’))

return decorated_function

“`

In the code above, we import the wraps function from the functools module, the flash, redirect, and url_for functions from Flask, and the current_user object from Flask-Login. We define the confirmed_required decorator function that takes a function as a parameter.

Inside the decorator function, we first check whether the user is authenticated and has not confirmed their email address. If that is the case, we flash a message informing the user that they need to confirm their email address and redirect them to the unconfirmed page.

If the user is authenticated and has confirmed their email address, we call the function passed as a parameter with the provided arguments. If the user is not authenticated, we redirect them to the login page.

Conclusion

Adding email confirmation and handling permissions are crucial features in any Flask application that requires user registration. In this article, we have explored how to generate a confirmation token, create the confirm email view function, and send emails with Flask-Mail.

We have also covered how to handle permissions by adding an unconfirmed route, adding the unconfirmed.html template, and creating a decorator function. These features are essential for securing the application and ensuring that only authorized users can access the application’s features.

Resend Email

Sometimes users may not receive the confirmation email or accidentally delete it. To handle such scenarios, we need to add an option to resend the confirmation email to the user’s email address.

In this section, we will explore adding a resend confirmation view function and testing its functionality.

Adding Resend Confirmation View Function

To add a resend confirmation functionality, we need to create a view function that generates a new confirmation token for the user and sends it to their email address. We will allow users to request a new confirmation email at /resend-confirmation route, which maps to the resend_confirmation view function.

Here is an example of a resend_confirmation view function:

“`

from flask import render_template, flash, redirect, url_for

from app.email import send_email

from app.decorators import confirmed_required

from flask_login import current_user

@app.route(‘/resend-confirmation’)

@confirmed_required

def resend_confirmation():

token = generate_confirmation_token(current_user.email)

confirm_url = url_for(‘confirm_email’, confirmation_token=token, _external=True)

send_email(current_user.email, ‘Confirm Your Email Address’, render_template(’email/confirm.html’, confirm_url=confirm_url))

flash(‘A new confirmation email has been sent to your email address.’, ‘success’)

return redirect(url_for(‘index’))

“`

In the code above, we first import the required modules and decorators, including the send_email function from the app.email module and the confirmed_required decorator from the app.decorators module. We then define the resend_confirmation view function as a confirmed_required view, ensuring that the user is authenticated and has already confirmed their email address.

Inside the view function, we generate a new confirmation token using the generate_confirmation_token function defined in the previous section. We then generate a confirmation URL using the url_for function and pass it to the send_email function, along with the user’s email address and a rendered email template.

The email template is a simple HTML template that includes a button that redirects the user to the confirm_email view function when clicked. The template is defined as follows:

“`

{% extends ’email/base.html’ %}

{% block content %}

Click the button below to confirm your email address:

{% endblock %}

“`

Testing the Functionality

To test the resend confirmation functionality, we can add a new user account and register them without confirming their email address. We can then log in to the application using the new account and navigate to the /unconfirmed route, which should display the “Unconfirmed Email Address” page.

From the Unconfirmed Email Address page, we can click on the “Resend Confirmation Email” button, which should redirect us to the /resend-confirmation route and trigger the resend_confirmation view function. We can then check our email inbox for the new confirmation email and click on the confirmation link to confirm our email address.

After confirming our email address, we can log out of the application, log in again using the same account, and be granted full access to the application.

Conclusion

In conclusion, adding email confirmation and allowing users to resend confirmation emails are crucial features for securing Flask applications that require user registration. Along with other features, such as email management, password reset, and user account management, these features ensure that only authorized