Login a User

Now that users are able to register for an account, we can define the view that allows them to login to the site and start a session. In views.py, my /login view is defined by the following:

@app.route('/login', methods=['GET', 'POST'])
def login():
    if request.method == 'POST':
        username = request.form['username']
        password = request.form['password']

        if not User(username).verify_password(password):
            flash('Invalid login.')
        else:
            session['username'] = username
            flash('Logged in.')
            return redirect(url_for('index'))

    return render_template('login.html')

The code here should look similar to the /register view. There is a similar form to fill out on login.html where a user types in their username and password. With the given username, a User object is initialized. The password they filled out in the form is verified with bcrypt.verify() against the hashed password that was retrieved from the corresponding :User node in the database. If the verification is successful it will return True, then a session object is created and session['username'] is set to the given username. The session object allows us to follow the user through requests with cookies. The user is then directed to the home page, on which they can add their first post. In models.py, the User.verify_password() method is defined as:

class User:

    ...

    def verify_password(self, password):
        user = self.find()
        if user:
            return bcrypt.verify(password, user['password'])
        else:
            return False

Note that py2neo.Node properties can be retrieved just as you would retrieve values from a Python dictionary. In this case, I got the password property off of the user object with user['password'].

The login.html template is nearly identical to the register.html template, with the exception of the form’s action which sends a POST request to the /login view instead:

{% extends "layout.html" %}
{% block body %}
  <h2>Login</h2>
    <form action="{{ url_for('login') }}" method="post">
        <dl>
            <dt>Username:</dt>
            <dd><input type="text" name="username"></dd>
            <dt>Password:</dt>
            <dd><input type="password" name="password"></dd>
        </dl>
        <input type="submit" value="Login">
    </form>
{% endblock %}

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