django-braces icondjango-braces 1.2.1

Reusable, generic mixins for Django
django-braces is a Django app that provides mixins to add easy functionality to Django class-based views, forms, and models.

Here are the generic mixins we've been using a lot lately. If you have any that you find useful, feel free to send them to us in a pull request. Please include example usage.

Mixins

- LoginRequiredMixin
- PermissionRequiredMixin
- SuperuserRequiredMixin
- UserFormKwargsMixin
- UserKwargModelFormMixin
- SuccessURLRedirectListMixin
- SetHeadlineMixin
- CreateAndRedirectToEditView

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.

from django.views.generic import TemplateView

from braces.views import LoginRequiredMixin


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

 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.

The permission required mixin has been very handy for our client's custom CMS. Again, 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. It would need to be modified to handle more than one. We haven't needed that yet, so this has worked out well for us.

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"


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"


UserFormKwargsMixin

In our clients 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. Example 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 new form mixin we just implemented this week 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. Example 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 handle CRUD within our CMS. Our 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"
 ...


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.

CreateAndRedirectToEditView

Mostly used for CRUD, where you're going to create an object and then move direct to the update view for that object. Your URL for the update view has to accept a PK for the object.

# urls.py
...
url(r"^users/create/$", UserCreateView.as_view(), name="cms_users_create"),
url(r"^users/edit/(?P\d+)/$", UserUpdateView.as_view(), name="cms_users_update"),
...

# views.py
from braces.views import CreateAndRedirectToEditView


class UserCreateView(CreateAndRedirectToEditView, CreateView):
 model = User
 ...

last updated on:
September 16th, 2012, 17:09 GMT
price:
FREE!
developed by:
Kenneth Love and Chris Jones
license type:
BSD License 
category:
ROOT \ Internet \ Django Plugins

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