Customizing templates

There are only one template to customize and it is called login.html. Example is:

{% extends 'base.html' %}
{% block title %}Login{% endblock %}
{% block messages %}
   {%if form.errors %}
     <ul class="alert alert-danger">
       {% for field, errors in form.errors.items() %}
         <li>{{field}} {% for error in errors %}{{ error }}{% endfor %}</li>
       {% endfor %}
   {% endif %}
{% endblock %}

{% block page_body %}
       <form action="{{ url_for('simplelogin.login', next=request.args.get('next', '/')) }}" method="post">
            <div class="form-group">
            {{ form.csrf_token }}
            {{form.username.label}}<div class="form-control">{{ form.username }}</div><br>
            {{form.password.label}}<div class="form-control"> {{ form.password }}</div><br>
           <input type="submit" value="Send">
{% endblock %}

Take a look at the example app.

And you can customize it in anyway you want and need, it receives a form in the context and it is a WTForms form. The submit should be done to request.path which is the same as the login view.

You can also use {% if is_logged_in() %} in your template if needed.

Customizing or translating message alerts

The default message alerts are:

Key Message CSS class
login_success login success! primary
login_failure invalid credentials danger
is_logged_in already logged in primary
logout Logged out! primary
login_required You need to login first warning
access_denied Access Denied primary
auth_error Authentication Error: {0} primary

In the auth_error message, the {0} in the authentication error is a required placeholder that is replaced by the validator error message.

from flask_simplelogin import Message,
# …

app = Flask(__name__)

messages = {
    'login_success': Message('Você está dentro!'),  # the default CSS class is `primary`
    'login_failure': 'ungültige Anmeldeinformationen',  # this also uses the default CSS class
    'is_logged_in': Message('Iam initium', 'success'), # this uses `success` as the CSS class
    'logout': None, # this disables the message for logout
    'login_required': 'Devi prima accedere',
    'access_denied': 'Acceso denegado',
    'auth_error': '授權錯誤: {0}'
SimpleLogin(app, messages=messages)

Custom validators

When you pass the must argument to login_required decorator, it can be a function or a list of functions. If function returns None, it means no error and validation passed. If function returns an error message (stringt), it means validation failed.

def be_admin(username):
    """Validator to check if user has admin role"""
    user_data = my_users.get(username)
    if not user_data or 'admin' not in user_data.get('roles', []):
        return "User does not have admin role"

def have_approval(username):
    """Validator: all users approved so return None"""

@login_required(must=[be_admin, have_approval])
def protected():
    return render_template('secret.html')

Take a look at the example app.