Other Mixins ¶

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

Contents

Other Mixins

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.