This document explains the usage of Django’s authentication system in its default configuration. This configuration has evolved to serve the most common project needs, handling a reasonably wide range of tasks, and has a careful implementation of passwords and permissions, and can handle many projects as is. For projects where authentication needs differ from the default, Django supports extensive extension and customization of authentication.
Django authentication provides both authentication and authorization, together and is generally referred to as the authenticaiton system, as these features somewhat coupled.
User objects are the core of the authentication system. They typically represent the people interacting with your site and are used to enable things like restricting access, registering user profiles, associating content with creators etc. Only one class of user exists in Django’s authentication framework, i.e., ‘superusers’ or admin ‘staff’ users are is just a user objects with special attributes set, not different classes of user objects.
The primary attributes of the default user are:
See the full API documentation for full reference, the documentation that follows is more task oriented.
The most direct way to create users is to use the included create_user() helper function:
>>> from django.contrib.auth.models import User
>>> user = User.objects.create_user('john', 'lennon@thebeatles.com', 'johnpassword')
# At this point, user is a User object that has already been saved
# to the database. You can continue to change its attributes
# if you want to change other fields.
>>> user.last_name = 'Lennon'
>>> user.save()
If you have the Django admin installed, you can also create users interactively.
manage.py syncdb prompts you to create a superuser the first time you run it with 'django.contrib.auth' in your INSTALLED_APPS. If you need to create a superuser at a later date, you can use a command line utility:
manage.py createsuperuser --username=joe --email=joe@example.com
You will be prompted for a password. After you enter one, the user will be created immediately. If you leave off the --username or the --email options, it will prompt you for those values.
Django does not store raw (clear text) passwords on the user model, but only a hash (see documentation of how passwords are managed for full details). Because of this, do not attempt to manipulate the password attribute of the user directly. This is why a a helper function is used when creating a user.
To change a user’s password, you have several options:
manage.py changepassword *username* offers a method of changing a User’s password from the command line. It prompts you to change the password of a given user which you must enter twice. If they both match, the new password will be changed immediately. If you do not supply a user, the command will attempt to change the password whose username matches the current system user.
You can also change a password programmatically, using set_password():
>>> from django.contrib.auth.models import User
>>> u = User.objects.get(username__exact='john')
>>> u.set_password('new password')
>>> u.save()
If you have the Django admin installed, you can also change user’s passwords on the authentication system’s admin pages.
Django also provides views and forms that may be used to allow users to change their own passwords.
To authenticate a given username and password, use authenticate(). It takes credentials in the form of keyword arguments, for the default configuration this is username and password, and it returns a User object if the password is valid for the given username. If the password is invalid, authenticate() returns None. Example:
from django.contrib.auth import authenticate
user = authenticate(username='john', password='secret')
if user is not None:
# the password verified for the user
if user.is_active:
print("User is valid, active and authenticated")
else:
print("The password is valid, but the account has been disabled!")
else:
# the authentication system was unable to verify the username and password
print("The username and password were incorrect.")
Django comes with a simple permissions system. It provides a way to assign permissions to specific users and groups of users.
It’s used by the Django admin site, but you’re welcome to use it in your own code.
The Django admin site uses permissions as follows:
Permissions can be set not only per type of object, but also per specific object instance. By using the has_add_permission(), has_change_permission() and has_delete_permission() methods provided by the ModelAdmin class, it is possible to customize permissions for different object instances of the same type.
When django.contrib.auth is listed in your INSTALLED_APPS setting, it will ensure that three default permissions – add, change and delete – are created for each Django model defined in one of your installed applications.
These permissions will be created when you run manage.py syncdb; the first time you run syncdb after adding django.contrib.auth to INSTALLED_APPS, the default permissions will be created for all previously-installed models, as well as for any new models being installed at that time. Afterward, it will create default permissions for new models each time you run manage.py syncdb.
Assuming you have an application with an app_label foo and a model named Bar, to test for basic permissions you should use:
The Permission model is rarely accessed directly.
django.contrib.auth.models.Group models are a generic way of categorizing users so you can apply permissions, or some other label, to those users. A user can belong to any number of groups.
A user in a group automatically has the permissions granted to that group. For example, if the group Site editors has the permission can_edit_home_page, any user in that group will have that permission.
Beyond permissions, groups are a convenient way to categorize users to give them some label, or extended functionality. For example, you could create a group 'Special users', and you could write code that could, say, give them access to a members-only portion of your site, or send them members-only email messages.
While custom permissions can be defined within a model’s Meta class, you can also create permissions directly. For example, you can create the can_publish permission for a BlogPost model in myapp:
from django.contrib.auth.models import Group, Permission
from django.contrib.contenttypes.models import ContentType
content_type = ContentType.objects.get(app_label='myapp', model='BlogPost')
permission = Permission.objects.create(codename='can_publish',
name='Can Publish Posts',
content_type=content_type)
The permission can then be assigned to a User via its user_permissions attribute or to a Group via its permissions attribute.
Django uses sessions and middleware to hook the authentication system into request objects.
These provide a request.user attribute on every request which represents the current user. If the current user has not logged in, this attribute will be set to an instance of AnonymousUser, otherwise it will be an instance of User.
You can tell them apart with is_authenticated(), like so:
if request.user.is_authenticated():
# Do something for authenticated users.
else:
# Do something for anonymous users.
If you have an authenticated user you want to attach to the current session - this is done with a login() function.
To log a user in, from a view, use login(). It takes an HttpRequest object and a User object. login() saves the user’s ID in the session, using Django’s session framework.
Note that any data set during the anonymous session is retained in the session after a user logs in.
This example shows how you might use both authenticate() and login():
from django.contrib.auth import authenticate, login
def my_view(request):
username = request.POST['username']
password = request.POST['password']
user = authenticate(username=username, password=password)
if user is not None:
if user.is_active:
login(request, user)
# Redirect to a success page.
else:
# Return a 'disabled account' error message
else:
# Return an 'invalid login' error message.
Calling authenticate() first
When you’re manually logging a user in, you must call authenticate() before you call login(). authenticate() sets an attribute on the User noting which authentication backend successfully authenticated that user (see the backends documentation for details), and this information is needed later during the login process. An error will be raise if you try to login a user object retrieved from the database directly.
To log out a user who has been logged in via django.contrib.auth.login(), use django.contrib.auth.logout() within your view. It takes an HttpRequest object and has no return value. Example:
from django.contrib.auth import logout
def logout_view(request):
logout(request)
# Redirect to a success page.
Note that logout() doesn’t throw any errors if the user wasn’t logged in.
When you call logout(), the session data for the current request is completely cleaned out. All existing data is removed. This is to prevent another person from using the same Web browser to log in and have access to the previous user’s session data. If you want to put anything into the session that will be available to the user immediately after logging out, do that after calling django.contrib.auth.logout().
The simple, raw way to limit access to pages is to check request.user.is_authenticated() and either redirect to a login page:
from django.shortcuts import redirect
def my_view(request):
if not request.user.is_authenticated():
return redirect('/login/?next=%s' % request.path)
# ...
...or display an error message:
from django.shortcuts import render
def my_view(request):
if not request.user.is_authenticated():
return render('myapp/login_error.html')
# ...
As a shortcut, you can use the convenient login_required() decorator:
from django.contrib.auth.decorators import login_required
@login_required
def my_view(request):
...
login_required() does the following:
By default, the path that the user should be redirected to upon successful authentication is stored in a query string parameter called "next". If you would prefer to use a different name for this parameter, login_required() takes an optional redirect_field_name parameter:
from django.contrib.auth.decorators import login_required
@login_required(redirect_field_name='my_redirect_field')
def my_view(request):
...
Note that if you provide a value to redirect_field_name, you will most likely need to customize your login template as well, since the template context variable which stores the redirect path will use the value of redirect_field_name as its key rather than "next" (the default).
login_required() also takes an optional login_url parameter. Example:
from django.contrib.auth.decorators import login_required
@login_required(login_url='/accounts/login/')
def my_view(request):
...
Note that if you don’t specify the login_url parameter, you’ll need to ensure that the settings.LOGIN_URL and your login view are properly associated. For example, using the defaults, add the following line to your URLconf:
(r'^accounts/login/$', 'django.contrib.auth.views.login'),
The settings.LOGIN_URL also accepts view function names and named URL patterns. This allows you to freely remap your login view within your URLconf without having to update the setting.
Note
The login_required decorator does NOT check the is_active flag on a user.
To limit access based on certain permissions or some other test, you’d do essentially the same thing as described in the previous section.
The simple way is to run your test on request.user in the view directly. For example, this view checks to make sure the user has an email in the desired domain:
def my_view(request):
if not '@example.com' in request.user.email:
return HttpResponse("You can't vote in this poll.")
# ...
As a shortcut, you can use the convenient user_passes_test decorator:
from django.contrib.auth.decorators import user_passes_test
def email_check(user):
return '@example.com' in request.user.email
@user_passes_test(email_check)
def my_view(request):
...
user_passes_test() takes a required argument: a callable that takes a User object and returns True if the user is allowed to view the page. Note that user_passes_test() does not automatically check that the User is not anonymous.
user_passes_test() takes an optional login_url argument, which lets you specify the URL for your login page (settings.LOGIN_URL by default).
For example:
@user_passes_test(email_check, login_url='/login/')
def my_view(request):
...
It’s a relatively common task to check whether a user has a particular permission. For that reason, Django provides a shortcut for that case: the permission_required() decorator.:
from django.contrib.auth.decorators import permission_required
@permission_required('polls.can_vote')
def my_view(request):
...
As for the User.has_perm() method, permission names take the form "<app label>.<permission codename>" (i.e. polls.can_vote for a permission on a model in the polls application).
Note that permission_required() also takes an optional login_url parameter. Example:
from django.contrib.auth.decorators import permission_required
@permission_required('polls.can_vote', login_url='/loginpage/')
def my_view(request):
...
As in the login_required() decorator, login_url defaults to settings.LOGIN_URL.
Added raise_exception parameter. If given, the decorator will raise PermissionDenied, prompting the 403 (HTTP Forbidden) view instead of redirecting to the login page.
To apply a permission to a class-based generic view, decorate the View.dispatch method on the class. See Decorating the class for details.
Django provides several views that you can use for handling login, logout, and password management. These make use of the stock auth forms but you can pass in your own forms as well.
Django provides no default template for the authentication views - however the template context is documented for each view below.
The built-in views all return a TemplateResponse instance, which allows you to easily customize the response data before rendering. For more details, see the TemplateResponse documentation.
Most built-in authentication views provide a URL name for easier reference. See the URL documentation for details on using named URL patterns.
URL name: login
See the URL documentation for details on using named URL patterns.
Here’s what django.contrib.auth.views.login does:
It’s your responsibility to provide the html for the login template , called registration/login.html by default. This template gets passed four template context variables:
If you’d prefer not to call the template registration/login.html, you can pass the template_name parameter via the extra arguments to the view in your URLconf. For example, this URLconf line would use myapp/login.html instead:
(r'^accounts/login/$', 'django.contrib.auth.views.login', {'template_name': 'myapp/login.html'}),
You can also specify the name of the GET field which contains the URL to redirect to after login by passing redirect_field_name to the view. By default, the field is called next.
Here’s a sample registration/login.html template you can use as a starting point. It assumes you have a base.html template that defines a content block:
{% extends "base.html" %}
{% block content %}
{% if form.errors %}
<p>Your username and password didn't match. Please try again.</p>
{% endif %}
<form method="post" action="{% url 'django.contrib.auth.views.login' %}">
{% csrf_token %}
<table>
<tr>
<td>{{ form.username.label_tag }}</td>
<td>{{ form.username }}</td>
</tr>
<tr>
<td>{{ form.password.label_tag }}</td>
<td>{{ form.password }}</td>
</tr>
</table>
<input type="submit" value="login" />
<input type="hidden" name="next" value="{{ next }}" />
</form>
{% endblock %}
If you have customized authentication (see Customizing Authentication) you can pass a custom authentication form to the login view via the authentication_form parameter. This form must accept a request keyword argument in its __init__ method, and provide a get_user method which returns the authenticated user object (this method is only ever called after successful form validation).
Logs a user out.
URL name: logout
Optional arguments:
Template context:
Logs a user out, then redirects to the login page.
URL name: No default URL provided
Optional arguments:
Allows a user to change their password.
URL name: password_change
Optional arguments:
Template context:
The page shown after a user has changed their password.
URL name: password_change_done
Optional arguments:
Allows a user to reset their password by generating a one-time use link that can be used to reset the password, and sending that link to the user’s registered email address.
URL name: password_reset
Optional arguments:
template_name: The full name of a template to use for displaying the password reset form. Defaults to registration/password_reset_form.html if not supplied.
email_template_name: The full name of a template to use for generating the email with the reset password link. Defaults to registration/password_reset_email.html if not supplied.
subject_template_name: The full name of a template to use for the subject of the email with the reset password link. Defaults to registration/password_reset_subject.txt if not supplied.
password_reset_form: Form that will be used to get the email of the user to reset the password for. Defaults to PasswordResetForm.
token_generator: Instance of the class to check the one time link. This will default to default_token_generator, it’s an instance of django.contrib.auth.tokens.PasswordResetTokenGenerator.
post_reset_redirect: The URL to redirect to after a successful password reset request.
from_email: A valid email address. By default Django uses the DEFAULT_FROM_EMAIL.
Template context:
Email template context:
Sample registration/password_reset_email.html (email body template):
Someone asked for password reset for email {{ email }}. Follow the link below:
{{ protocol}}://{{ domain }}{% url 'password_reset_confirm' uidb36=uid token=token %}
The same template context is used for subject template. Subject must be single line plain text string.
The page shown after a user has been emailed a link to reset their password. This view is called by default if the password_reset() view doesn’t have an explicit post_reset_redirect URL set.
URL name: password_reset_done
Optional arguments:
Presents a form for entering a new password.
URL name: password_reset_confirm
Optional arguments:
Template context:
Presents a view which informs the user that the password has been successfully changed.
URL name: password_reset_complete
Optional arguments:
Redirects to the login page, and then back to another URL after a successful login.
Required arguments:
Optional arguments:
If you don’t want to use the built-in views, but want the convenience of not having to write forms for this functionality, the authentication system provides several built-in forms located in django.contrib.auth.forms:
A form used in the admin interface to change a user’s password.
A form for logging a user in.
A form for allowing a user to change their password.
A form for generating and emailing a one-time use link to reset a user’s password.
A form that lets a user change his/her password without entering the old password.
A form used in the admin interface to change a user’s information and permissions.
A form for creating a new user.
The currently logged-in user and his/her permissions are made available in the template context when you use RequestContext.
Technicality
Technically, these variables are only made available in the template context if you use RequestContext and your TEMPLATE_CONTEXT_PROCESSORS setting contains "django.contrib.auth.context_processors.auth", which is default. For more, see the RequestContext docs.
When rendering a template RequestContext, the currently logged-in user, either a User instance or an AnonymousUser instance, is stored in the template variable {{ user }}:
{% if user.is_authenticated %}
<p>Welcome, {{ user.username }}. Thanks for logging in.</p>
{% else %}
<p>Welcome, new user. Please log in.</p>
{% endif %}
This template context variable is not available if a RequestContext is not being used.
The currently logged-in user’s permissions are stored in the template variable {{ perms }}. This is an instance of django.contrib.auth.context_processors.PermWrapper, which is a template-friendly proxy of permissions.
In the {{ perms }} object, single-attribute lookup is a proxy to User.has_module_perms. This example would display True if the logged-in user had any permissions in the foo app:
{{ perms.foo }}
Two-level-attribute lookup is a proxy to User.has_perm. This example would display True if the logged-in user had the permission foo.can_vote:
{{ perms.foo.can_vote }}
Thus, you can check permissions in template {% if %} statements:
{% if perms.foo %}
<p>You have permission to do something in the foo app.</p>
{% if perms.foo.can_vote %}
<p>You can vote!</p>
{% endif %}
{% if perms.foo.can_drive %}
<p>You can drive!</p>
{% endif %}
{% else %}
<p>You don't have permission to do anything in the foo app.</p>
{% endif %}
It is possible to also look permissions up by {% if in %} statements. For example:
{% if 'foo' in perms %}
{% if 'foo.can_vote' in perms %}
<p>In lookup works, too.</p>
{% endif %}
{% endif %}
When you have both django.contrib.admin and django.contrib.auth installed, the admin provides a convenient way to view and manage users, groups, and permissions. Users can be created and deleted like any Django model. Groups can be created, and permissions can be assigned to users or groups. A log of user edits to models made within the admin is also stored and displayed.
You should see a link to “Users” in the “Auth” section of the main admin index page. The “Add user” admin page is different than standard admin pages in that it requires you to choose a username and password before allowing you to edit the rest of the user’s fields.
Also note: if you want a user account to be able to create users using the Django admin site, you’ll need to give them permission to add users and change users (i.e., the “Add user” and “Change user” permissions). If an account has permission to add users but not to change them, that account won’t be able to add users. Why? Because if you have permission to add users, you have the power to create superusers, which can then, in turn, change other users. So Django requires add and change permissions as a slight security measure.
User passwords are not displayed in the admin (nor stored in the database), but the password storage details are displayed. Included in the display of this information is a link to a password change form that allows admins to change user passwords.
Dec 23, 2012