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 allows you to statically or programmatically set the headline of any of your views. Ideally, you’ll write as few templates as possible, so a mixin like this helps you 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 django.utils.translation import ugettext_lazy as _
from django.views import TemplateView

from braces.views import SetHeadlineMixin


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

Dynamic Example

from datetime import date

from django.views import TemplateView

from braces.views import SetHeadlineMixin


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

    def get_headline(self):
        return u"This is our headline for {0}".format(date.today().isoformat())

For both usages, the context now contains a headline key with your headline.

StaticContextMixin

New in version 1.4.

The StaticContextMixin allows you to easily set static context data by using the static_context property.

Note

While it’s possible to override the StaticContextMixin.get_static_context method, it’s not very practical. If you have a need to override a method for dynamic context data it’s best to override the standard get_context_data method of Django’s generic class-based views.

View Example

# views.py

from django.views import TemplateView

from braces.views import StaticContextMixin


class ContextTemplateView(StaticContextMixin, TemplateView):
    static_context = {u"nav_home": True}

URL Example

# urls.py

urlpatterns = patterns(
    '',
    url(ur"^$",
        ContextTemplateView.as_view(
            template_name=u"index.html",
            static_context={u"nav_home": True}
        ),
        name=u"index")
)

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 = [u"user"]
    template_name = u"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 = [u"post_set"]  # where the Post model has an FK to the User model as an author.
    template_name = u"users/detail.html"

JSONResponseMixin

Changed in version 1.1: render_json_response now accepts a status 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 = {u"indent": 2}

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

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

        return self.render_json_response(context_dict)

You can additionally use the AjaxResponseMixin

# views.py
from django.views import DetailView

from braces import views


class UserProfileView(views.JSONResponseMixin,
                      views.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 django.views import DetailView

from braces.views import JSONResponseMixin


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

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

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

        return self.render_json_response(context_dict)

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

The JSONResponseMixin provides another class-level variable json_encoder_class to use a custom json encoder with json.dumps. By default it is django.core.serializers.json.DjangoJsonEncoder

from django.core.serializers.json import DjangoJSONEncoder

from braces.views import JSONResponseMixin


class SetJSONEncoder(DjangoJSONEncoder):
    """
    A custom JSONEncoder extending `DjangoJSONEncoder` to handle serialization
    of `set`.
    """
    def default(self, obj):
        if isinstance(obj, set):
            return list(obj)
        return super(DjangoJSONEncoder, self).default(obj)


class GetSetDataView(JSONResponseMixin, View):
    json_encoder_class = SetJSONEncoder

    def get(self, request, *args, **kwargs):
        numbers_set = set(range(10))
        data = {'numbers': numbers_set}
        return self.render_json_response(data)

JsonRequestResponseMixin

New in version 1.3.

A mixin that attempts to parse the request as JSON. If the 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 import views

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

    def post(self, request, *args, **kwargs):
        try:
            burrito = self.request_json[u"burrito"]
            toppings = self.request_json[u"toppings"]
        except KeyError:
            error_dict = {u"message":
               u"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(
            {u"message": u"Your order has been placed!"})

AjaxResponseMixin

This mixin provides hooks for altenate processing of AJAX requests based on HTTP verb.

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 import views

class SomeView(views.JSONResponseMixin, views.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)

Note

This mixin is only useful if you need to have behavior in your view fork based on request.is_ajax().

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 ordered 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
from django.views import ListView

from braces.views import OrderableListMixin


class OrderableListView(OrderableListMixin, ListView):
    model = Article
    orderable_columns = (u"id", u"title",)
    orderable_columns_default = u"id"

Or by using similarly-named methods to set the ordering constraints more dynamically:

# views.py
from django.views import ListView

from braces.views import OrderableListMixin


class OrderableListView(OrderableListMixin, ListView):
    model = Article

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

    def get_orderable_columns_default(self):
        # return a string
        return u"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

You can also override the default ordering from "asc" to "desc" by setting the "ordering_default" in your view class.

# views.py
from django.views import ListView

from braces.views import OrderableListMixin


class OrderableListView(OrderableListMixin, ListView):
    model = Article
    orderable_columns = (u"id", u"title",)
    orderable_columns_default = u"id"
    ordering_default = u"desc"

This will reverse the order of list objects if no query param is given.

Front-end Example Usage

If you’re using bootstrap you could create a template like the following:

<div class="table-responsive">
    <table class="table table-striped table-bordered">
        <tr>
            <th><a class="order-by-column" data-column="id" href="#">ID</a></th>
            <th><a class="order-by-column" data-column="title" href="#">Title</a></th>
        </tr>
        {% for object in object_list %}
            <tr>
                <td>{{ object.id }}</td>
                <td>{{ object.title }}</td>
            </tr>
        {% endfor %}
    </table>
</div>

<script>
function setupOrderedColumns(order_by, orderin) {

    $('.order-by-column').each(function() {

        var $el = $(this),
            column_name = $el.data('column'),
            href = location.href,
            next_order = 'asc',
            has_query_string = (href.indexOf('?') !== -1),
            order_by_param,
            ordering_param;

        if (order_by === column_name) {
            $el.addClass('current');
            $el.addClass(ordering);
            $el.append('<span class="caret"></span>');
            if (ordering === 'asc') {
                $el.addClass('dropup');
                next_order = 'desc';
            }
        }

        order_by_param = "order_by=" + column_name;
        ordering_param = "ordering=" + next_order;

        if (!has_query_string) {
            href = '?' + order_by_param + '&' + ordering_param;
        } else {
            if (href.match(/ordering=(asc|desc)/)) {
                href = href.replace(/ordering=(asc|desc)/, ordering_param);
            } else {
                href += '&' + ordering_param;
            }

            if (href.match(/order_by=[_\w]+/)) {
                href = href.replace(/order_by=([_\w]+)/, order_by_param);
            } else {
                href += '&' + order_by_param;
            }

        }

        $el.attr('href', href);

    });
}
setupOrderedColumns('{{ order_by }}', '{{ ordering }}');
</script>

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 "{0}-{1}".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.

MessageMixin

New in version 1.4.

A mixin that adds a messages attribute on the view which acts as a wrapper to django.contrib.messages and passes the request object automatically.

Warning

If you’re using Django 1.4, then the message attribute is only available after the base view’s dispatch method has been called (so our second example would not work for instance).

from django.views.generic import TemplateView

from braces.views import MessageMixin


class MyView(MessageMixin, TemplateView):
    """
    This view will add a debug message which can then be displayed
    in the template.
    """
    template_name = "my_template.html"

    def get(self, request, *args, **kwargs):
        self.messages.debug("This is a debug message.")
        return super(MyView, self).get(request, *args, **kwargs)
from django.contrib import messages
from django.views.generic import TemplateView

from braces.views import MessageMixin


class OnlyWarningView(MessageMixin, TemplateView):
    """
    This view will only show messages that have a level
    above `warning`.
    """
    template_name = "my_template.html"

    def dispatch(self, request, *args, **kwargs):
        self.messages.set_level(messages.WARNING)
        return super(OnlyWarningView, self).dispatch(request, *args, **kwargs)

AllVerbsMixin

New in version 1.4.

This mixin allows you to specify a single method that will response to all HTTP verbs, making a class-based view behave much like a function-based view.

from django.views import TemplateView

from braces.views import AllVerbsMixin


class JustShowItView(AllVerbsMixin, TemplateView):
    template_name = "just/show_it.html"

    def all(self, request, *args, **kwargs):
        return super(JustShowItView, self).get(request, *args, **kwargs)

If you need to change the name of the method called, provide a new value to the all_handler attribute (default is 'all')

HeaderMixin

New in version 1.11.

This mixin allows you to add arbitrary HTTP header to a response. Static headers can be defined in the headers attribute of the view.

from django.views import TemplateView

from braces.views import HeaderMixin


class StaticHeadersView(HeaderMixin, TemplateView):
    template_name = "some/headers.html"
    headers = {
        'X-Header-Sample': 'some value',
        'X-Some-Number': 42
    }

If you need to set the headers dynamically, e.g depending on some request information, override the get_headers method instead.

from django.views import TemplateView

from braces.views import HeaderMixin


class EchoHeadersView(HeaderMixin, TemplateView):
    template_name = "some/headers.html"

    def get_headers(self, request):
        """
        Echo back request headers with ``X-Request-`` prefix.
        """
        for key, value in request.META.items():
            yield "X-Request-{}".format(key), value