Welcome to django-braces’s documentation!

You can view the code of our project or fork it and add your own mixins (please, send them back to us), on Github.

Access Mixins

These mixins all control a user’s access to a given view. Since they all extend the AccessMixin, the implement a common API that includes the following class attributes:

login_url = settings.LOGIN_URL
redirect_field_name = REDIRECT_FIELD_NAME
raise_exception = False

The raise_exception attribute will cause the view to raise a PermissionDenied exception if it is set to True, otherwise the view will redirect to the login view provided.

LoginRequiredMixin

This mixin is rather simple and is generally the first inherited class in any of our views. If we don’t have an authenticated user there’s no need to go any further. If you’ve used Django before you are probably familiar with the login_required decorator. All we are doing here is requiring a user to be authenticated to be able to get to this view.

While this doesn’t look like much, it frees us up from having to manually overload the dispatch method on every single view that requires a user to be authenticated. If that’s all that is needed on this view, we just saved 3 lines of code. Example usage below.

Note

As of version 1.0, the LoginRequiredMixin has been rewritten to behave like the rest of the access mixins. It now accepts login_url, redirect_field_name and raise_exception.

Note

This should be the left-most mixin of a view, except when combined with CsrfExemptMixin - which in that case should be the left-most mixin.

from django.views.generic import TemplateView

from braces.views import LoginRequiredMixin


class SomeSecretView(LoginRequiredMixin, TemplateView):
    template_name = "path/to/template.html"

    #optional
    login_url = "/signup/"
    redirect_field_name = "hollaback"
    raise_exception = True

    def get(self, request):
        return self.render_to_response({})

PermissionRequiredMixin

This mixin was originally written, I believe, by Daniel Sokolowski (code here), but we have updated it to eliminate an unneeded render if the permissions check fails.

Rather than overloading the dispatch method manually on every view that needs to check for the existence of a permission, we inherit this class and set the permission_required class attribute on our view. If you don’t specify permission_required on your view, an ImproperlyConfigured exception is raised reminding you that you haven’t set it.

The one limitation of this mixin is that it can only accept a single permission. If you need multiple permissions use MultiplePermissionsRequiredMixin.

In our normal use case for this mixin, LoginRequiredMixin comes first, then the PermissionRequiredMixin. If we don’t have an authenticated user, there is no sense in checking for any permissions.

Note

If you are using Django’s built in auth system, superusers automatically have all permissions in your system.

from braces.views import LoginRequiredMixin, PermissionRequiredMixin


class SomeProtectedView(LoginRequiredMixin, PermissionRequiredMixin, TemplateView):
    permission_required = "auth.change_user"
    template_name = "path/to/template.html"

MultiplePermissionsRequiredMixin

The multiple permissions required view mixin is a more powerful version of the PermissionRequiredMixin. This view mixin can handle multiple permissions by setting the mandatory permissions attribute as a dict with the keys any and/or all to a list/tuple of permissions. The all key requires the request.user to have all of the specified permissions. The any key requires the request.user to have at least ONE of the specified permissions. If you only need to check a single permission, the PermissionRequiredMixin is all you need.

Note

If you are using Django’s built in auth system, superusers automatically have all permissions in your system.

from braces.views import LoginRequiredMixin, MultiplePermissionsRequiredMixin


class SomeProtectedView(LoginRequiredMixin,
                        MultiplePermissionsRequiredMixin,
                        TemplateView):

    #required
    permissions = {
        "all": ("blog.add_post", "blog.change_post"),
        "any": ("blog.delete_post", "user.change_user")
    }

GroupRequiredMixin

New in version 1.2.

The group required view mixin ensures that the requesting user is in the group or groups specified. This view mixin can handle multiple groups by setting the mandatory group_required attribute as a list or tuple.

Note

The mixin assumes you’re using Django’s default Group model and that your user model provides groups as a ManyToMany relationship. If this is not the case, you’ll need to override check_membership in the mixin to handle your custom set up.

Standard Django Usage

from braces.views import GroupRequiredMixin


class SomeProtectedView(GroupRequiredMixin, TemplateView):

    #required
    group_required = u'editors'

Custom Group Usage

from braces.views import GroupRequiredMixin


class SomeProtectedView(GroupRequiredMixin, TemplateView):

    #required
    group_required = u'editors'

    def check_membership(self, group):
        ...
        # Check some other system for group membership
        if user_in_group:
            return True
        else:
            return False

UserPassesTestMixin

New in version dev.

Mixin that reimplements the user_passes_test decorator. This is helpful for much more complicated cases than checking if user is_superuser (for example if their email is from specific a domain).

from braces.views import UserPassesTestMixin

class SomeUserPassView(UserPassesTestMixin, TemplateView):
    def test_func(self, user):
        return (user.is_staff and not user.is_superuser
                and user.email.endswith("mydomain.com"))

SuperuserRequiredMixin

Another permission-based mixin. This is specifically for requiring a user to be a superuser. Comes in handy for tools that only privileged users should have access to.

from braces.views import LoginRequiredMixin, SuperuserRequiredMixin


class SomeSuperuserView(LoginRequiredMixin, SuperuserRequiredMixin, TemplateView):
    template_name = "path/to/template.html"

StaffuserRequiredMixin

Similar to SuperuserRequiredMixin, this mixin allows you to require a user with is_staff set to True.

from braces.views import LoginRequiredMixin, StaffuserRequiredMixin


class SomeStaffuserView(LoginRequiredMixin, StaffuserRequiredMixin, TemplateView):
    template_name = "path/to/template.html"

Form Mixins

All of these mixins, with one exception, modify how forms are handled within views. The UserKwargModelFormMixin is a mixin for use in forms to auto-pop a user kwarg.

CsrfExemptMixin

If you have Django’s CSRF protection middleware enabled you can exempt views using the csrf_exempt decorator. This mixin exempts POST requests from the CSRF protection middleware without requiring that you decorate the dispatch method.

Note

This should always be the left-most mixin of a view.

from django.views.generic import UpdateView

from braces.views import LoginRequiredMixin, CsrfExemptMixin

from profiles.models import Profile


class UpdateProfileView(LoginRequiredMixin, CsrfExemptMixin, UpdateView):
    model = Profile

UserFormKwargsMixin

In one of our client’s CMS, we have a lot of form-based views that require a user to be passed in for permission-based form tools. For example, only superusers can delete or disable certain objects. To custom tailor the form for users, we have to pass that user instance into the form and based on their permission level, change certain fields or add specific options within the forms __init__ method.

This mixin automates the process of overloading the get_form_kwargs (this method is available in any generic view which handles a form) method and stuffs the user instance into the form kwargs. We can then pop the user off in the form and do with it what we need. Always remember to pop the user from the kwargs before calling super on your form, otherwise the form gets an unexpected keyword argument and everything blows up.

Usage

from django.views.generic import CreateView

from braces.views import LoginRequiredMixin, UserFormKwargsMixin
from next.example import UserForm


class SomeSecretView(LoginRequiredMixin, UserFormKwargsMixin,
    TemplateView):

    form_class = UserForm
    model = User
    template_name = "path/to/template.html"

This obviously pairs very nicely with the following Form mixin.

UserKwargModelFormMixin

The UserKwargModelFormMixin is a form mixin to go along with our UserFormKwargsMixin. This becomes the first inherited class of our forms that receive the user keyword argument. With this mixin, we have automated the popping off of the keyword argument in our form and no longer have to do it manually on every form that works this way. While this may be overkill for a weekend project, for us, it speeds up adding new features.

Usage

from braces.forms import UserKwargModelFormMixin


class UserForm(UserKwargModelFormMixin, forms.ModelForm):
    class Meta:
        model = User

    def __init__(self, *args, **kwargs):
        super(UserForm, self).__init__(*args, **kwargs)

        if not self.user.is_superuser:
            del self.fields["group"]

SuccessURLRedirectListMixin

The SuccessURLRedirectListMixin is a bit more tailored to how we have handled CRUD within the CMSes we’ve built. One CMS’s workflow, by design, redirects the user to the ListView for whatever model they are working with, whether they are creating a new instance, editing an existing one or deleting one. Rather than having to override get_success_url on every view, we simply use this mixin and pass it a reversible route name. Example:

# urls.py
url(r"^users/$", UserListView.as_view(), name="cms_users_list"),

# views.py
from braces.views import (LoginRequiredMixin, PermissionRequiredMixin,
    SuccessURLRedirectListMixin)


class UserCreateView(LoginRequiredMixin, PermissionRequiredMixin,
    SuccessURLRedirectListMixin, CreateView):

    form_class = UserForm
    model = User
    permission_required = "auth.add_user"
    success_list_url = "cms_users_list"
    ...

FormValidMessageMixin

New in version 1.2.

The FormValidMessageMixin allows you to to statically or programmatically set a message to be returned using Django’s messages framework when the form is valid. The returned message is controlled by the form_valid_message property which can either be set on the view or returned by the get_form_valid_message method. The message is not processed until the end of the form_valid method.

Warning

This mixin requires the Django messages app to be enabled.

Note

This mixin is designed for use with Django’s generic form class-based views, e.g. FormView, CreateView, UpdateView

Static Example

from django.views.generic import CreateView

from braces.views import FormValidMessageMixin


class BlogPostCreateView(FormValidMessageMixin, CreateView):
    form_class = PostForm
    model = Post
    form_valid_message = 'Blog post created!'

Dynamic Example

from django.views.generic import CreateView

from braces.views import FormValidMessageMixin


class BlogPostCreateView(FormValidMessageMixin, CreateView):
    form_class = PostForm
    model = Post

    def get_form_valid_message(self):
        return '{0} created!'.format(self.object.title)

FormInvalidMessageMixin

New in version 1.2.

The FormInvalidMessageMixin allows you to to statically or programmatically set a message to be returned using Django’s messages framework when the form is invalid. The returned message is controlled by the form_invalid_message property which can either be set on the view or returned by the get_form_invalid_message method. The message is not processed until the end of the form_invalid method.

Warning

This mixin requires the Django messages app to be enabled.

Note

This mixin is designed for use with Django’s generic form class-based views, e.g. FormView, CreateView, UpdateView

Static Example

from django.views.generic import CreateView

from braces.views import FormInvalidMessageMixin


class BlogPostCreateView(FormInvalidMessageMixin, CreateView):
    form_class = PostForm
    model = Post
    form_invalid_message = 'Oh snap, something went wrong!'

Dynamic Example

from django.views.generic import CreateView

from braces.views import FormInvalidMessageMixin


class BlogPostCreateView(FormInvalidMessageMixin, CreateView):
    form_class = PostForm
    model = Post

    def get_form_invalid_message(self):
        return 'Some custom message'

FormMessagesMixin

New in version 1.2.

FormMessagesMixin is a convenience mixin which combines FormValidMessageMixin and FormInvalidMessageMixin since we commonly provide messages for both states (form_valid, form_invalid).

Warning

This mixin requires the Django messages app to be enabled.

Static & Dynamic Example

from django.views.generic import CreateView

from braces.views import FormMessagesMixin


class BlogPostCreateView(FormMessagesMixin, CreateView):
    form_class = PostForm
    form_invalid_message = 'Something went wrong, post was not saved'
    model = Post

    def get_form_valid_message(self):
        return '{0} created!'.format(self.object.title)

Other Mixins

These mixins handle other random bits of Django’s views, like controlling output, controlling content types, or setting values in the context.

SetHeadlineMixin

The SetHeadlineMixin is a newer edition to our client’s CMS. It allows us to statically or programmatically set the headline of any of our views. We like to write as few templates as possible, so a mixin like this helps us reuse generic templates. Its usage is amazingly straightforward and works much like Django’s built-in get_queryset method. This mixin has two ways of being used.

Static Example

from braces.views import SetHeadlineMixin


class HeadlineView(SetHeadlineMixin, TemplateView):
    headline = "This is our headline"
    template_name = "path/to/template.html"

Dynamic Example

from datetime import date

from braces.views import SetHeadlineMixin


class HeadlineView(SetHeadlineMixin, TemplateView):
    template_name = "path/to/template.html"

    def get_headline(self):
        return u"This is our headline for %s" % date.today().isoformat()

In both usages, in the template, just print out {{ headline }} to show the generated headline.

SelectRelatedMixin

A simple mixin which allows you to specify a list or tuple of foreign key fields to perform a select_related on. See Django’s docs for more information on select_related.

# views.py
from django.views.generic import DetailView

from braces.views import SelectRelatedMixin

from profiles.models import Profile


class UserProfileView(SelectRelatedMixin, DetailView):
    model = Profile
    select_related = ["user"]
    template_name = "profiles/detail.html"

PrefetchRelatedMixin

A simple mixin which allows you to specify a list or tuple of reverse foreign key or ManyToMany fields to perform a prefetch_related on. See Django’s docs for more information on prefetch_related.

# views.py
from django.contrib.auth.models import User
from django.views.generic import DetailView

from braces.views import PrefetchRelatedMixin


class UserView(PrefetchRelatedMixin, DetailView):
    model = User
    prefetch_related = ["post_set"]  # where the Post model has an FK to the User model as an author.
    template_name = "users/detail.html"

JSONResponseMixin

Changed in version 1.1: render_json_response now accepts a status_code keyword argument. json_dumps_kwargs class-attribute and get_json_dumps_kwargs method to provide arguments to the json.dumps() method.

A simple mixin to handle very simple serialization as a response to the browser.

# views.py
from django.views.generic import DetailView

from braces.views import JSONResponseMixin

class UserProfileAJAXView(JSONResponseMixin, DetailView):
    model = Profile
    json_dumps_kwargs = {'indent': 2}

    def get(self, request, *args, **kwargs):
        self.object = self.get_object()

        context_dict = {
            'name': self.object.user.name,
            'location': self.object.location
        }

        return self.render_json_response(context_dict)

You can additionally use the AjaxResponseMixin

# views.py
from braces.views import AjaxResponseMixin

class UserProfileView(JSONResponseMixin, AjaxResponseMixin, DetailView):
    model = Profile

    def get_ajax(self, request, *args, **kwargs):
        return self.render_json_object_response(self.get_object())

The JSONResponseMixin provides a class-level variable to control the response type as well. By default it is application/json, but you can override that by providing the content_type variable a different value or, programmatically, by overriding the get_content_type() method.

from braces.views import JSONResponseMixin

class UserProfileAJAXView(JSONResponseMixin, DetailView):
    content_type = 'application/javascript'
    model = Profile

    def get(self, request, *args, **kwargs):
        self.object = self.get_object()

        context_dict = {
            'name': self.object.user.name,
            'location': self.object.location
        }

        return self.render_json_response(context_dict)

    def get_content_type(self):
        # Shown just for illustrative purposes
        return 'application/javascript'

JsonRequestResponseMixin

New in version 1.3.

A mixin that attempts to parse request as JSON. If request is properly formatted, the json is saved to self.request_json as a Python object. request_json will be None for imparsible requests.

To catch requests that aren’t JSON-formatted, set the class attribute require_json to True.

Override the class attribute error_response_dict to customize the default error message.

It extends JSONResponseMixin, so those utilities are available as well.

Note: To allow public access to your view, you’ll need to use the csrf_exempt decorator or CsrfExemptMixin.

from django.views.generic import View

from braces.views import CsrfExemptMixin, JsonRequestResponseMixin

class SomeView(CsrfExemptMixin, JsonRequestResponseMixin, View):
    require_json = True

    def post(self, request, *args, **kwargs):
        try:
            burrito = self.request_json['burrito']
            toppings = self.request_json['toppings']
        except:
            error_dict = {'message':
                'your order must include a burrito AND toppings'}
            return self.render_bad_request_response(error_dict)
        place_order(burrito, toppings)
        return self.render_json_response(
            {'message': 'Your order has been placed!'})

AjaxResponseMixin

A mixin to allow you to provide alternative methods for handling AJAX requests.

To control AJAX-specific behavior, override get_ajax, post_ajax, put_ajax, or delete_ajax. All four methods take request, *args, and **kwargs like the standard view methods.

# views.py
from django.views.generic import View

from braces.views import AjaxResponseMixin, JSONResponseMixin

class SomeView(JSONResponseMixin, AjaxResponseMixin, View):
    def get_ajax(self, request, *args, **kwargs):
        json_dict = {
            'name': "Benny's Burritos",
            'location': "New York, NY"
        }
        return self.render_json_response(json_dict)

OrderableListMixin

New in version 1.1.

A mixin to allow easy ordering of your queryset basing on the GET parameters. Works with ListView.

To use it, define columns that the data can be order by as well as the default column to order by in your view. This can be done either by simply setting the class attributes...

# views.py
class OrderableListView(OrderableListMixin, ListView):
    model = Article
    orderable_columns = ('id', 'title',)
    orderable_columns_default = 'id'

...or by using similarly name methods to set the ordering constraints more dynamically:

# views.py
class OrderableListView(OrderableListMixin, ListView):
    model = Article

    def get_orderable_columns(self):
        # return an iterable
        return ('id', 'title', )

    def get_orderable_columns_default(self):
        # return a string
        return 'id'

The orderable_columns restriction is here in order to stop your users from launching inefficient queries, like ordering by binary columns.

OrderableListMixin will order your queryset basing on following GET params:

  • order_by: column name, e.g. 'title'
  • ordering: ‘asc’ (default) or 'desc'

Example url: http://127.0.0.1:8000/articles/?order_by=title&ordering=asc

CanonicalSlugDetailMixin

New in version 1.3.

A mixin that enforces a canonical slug in the url. Works with DetailView.

If a urlpattern takes a object’s pk and slug as arguments and the slug url argument does not equal the object’s canonical slug, this mixin will redirect to the url containing the canonical slug.

To use it, the urlpattern must accept both a pk and slug argument in its regex:

# urls.py
urlpatterns = patterns('',
    url(r'^article/(?P<pk>\d+)-(?P<slug>[-\w]+)$')
    ArticleView.as_view(),
    'view_article'
)

Then create a standard DetailView that inherits this mixin:

class ArticleView(CanonicalSlugDetailMixin, DetailView):
    model = Article

Now, given an Article object with {pk: 1, slug: 'hello-world'}, the url http://127.0.0.1:8000/article/1-goodbye-moon will redirect to http://127.0.0.1:8000/article/1-hello-world with the HTTP status code 301 Moved Permanently. Any other non-canonical slug, not just ‘goodbye-moon’, will trigger the redirect as well.

Control the canonical slug by either implementing the method get_canonical_slug() on the model class:

class Article(models.Model):
    blog = models.ForeignKey('Blog')
    slug = models.SlugField()

    def get_canonical_slug(self):
      return "{}-{}".format(self.blog.get_canonical_slug(), self.slug)

Or by overriding the get_canonical_slug() method on the view:

class ArticleView(CanonicalSlugDetailMixin, DetailView):
    model = Article

    def get_canonical_slug():
        import codecs
        return codecs.encode(self.get_object().slug, 'rot_13')

Given the same Article as before, this will generate urls of http://127.0.0.1:8000/article/1-my-blog-hello-world and http://127.0.0.1:8000/article/1-uryyb-jbeyq, respectively.

Indices and tables