How do I inject the same context into many different Django views?
I want to put information about one object in many views without repeating it in get_context_data in every view. Since I understand that I need a class with get_context_data inside, I can mix with other views. Here in my example I want to see "some_object" in the context of UpdateAnotherObjectView:
class BaseObjectInfoView(View):
def get_context_data(self, **kwargs):
context_data = super(BaseObjectInfoView, self).get_context_data(**kwargs)
context_data['some_object'] = SomeObjects.objects.get(pk=1)
return context_data
class UpdateAnotherObjectView(BaseObjectInfo, UpdateView):
template_name = 'create_object.html'
form_class = AnotherObjectForm
model = AnotherObjects
def get_context_data(self, **kwargs):
context_data = super(UpdateAnotherObjectView, self).get_context_data(**kwargs)
context_data['all_another_objects'] = AnotherObjects.objects.all()
return context_data
it works, but get_context_data is not part of the parent class "View". Maybe I need a more special class for inheritance in BaseObjectInfoView?
or maybe it's better to build the context with a different method?
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Mixins don't have to be views, but it helps the IDE if they have methods that they override.
The contexts are handled with django.views.generic.base.ContextMixin
(more on this very handy site ). So the cool views on things would be this:
from django.views import generic
class WebsiteCommonMixin(generic.base.ContextMixin):
page_title = ''
active_menu = None
def get_context_data(self, **kwargs):
context = super(WebsiteCommonMixin, self).get_context_data(**kwargs)
context.update(dict(page_title=self.page_title, active_menu=self.active_menu))
return context
class NewsListView(WebsiteCommonMixin, ListView):
page_title = 'News list'
active_menu = 'News'
model = News
paginate_by = 12
I do this for a lot of projects and the simple views you have to create anyway are completely declarative. And just, I mean they can be made up of mulitple mixins, all of which do the heavy lifting in get_queryset, get_context_data, or form_valid. A more complex example, straight from the project:
class FeedbackMixin(object):
message = 'Well Done!'
def __init__(self):
self._message_kwargs = {}
super().__init__()
def add_message_kwarg(self, name, value) -> None:
self._message_kwargs[name] = value
def format_message(self, kwargs) -> str:
return self.message.format(**kwargs)
def generate_message(self) -> None:
msg = self.format_message(self._message_kwargs)
messages.success(getattr(self, 'request'), msg)
class ModelFeedbackMixin(FeedbackMixin, generic.edit.ModelFormMixin):
success_view_name = None
success_url_kwargs = None
def get_success_url_kwargs(self):
return self.success_url_kwargs
def get_success_url(self) -> str:
success_url_kwargs = self.get_success_url_kwargs()
if not self.success_view_name:
url = super().get_success_url()
elif success_url_kwargs is not None:
url = reverse(self.success_view_name, kwargs=success_url_kwargs)
else:
if hasattr(self.object, 'slug'):
url_kwargs = {'slug': self.object.slug}
else:
url_kwargs = {'pk': self.object.pk}
url = reverse(self.success_view_name, kwargs=url_kwargs)
return url
def form_valid(self, form):
response = super().form_valid(form)
self.generate_message()
return response
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Perhaps this way could be easier to read ...
def add_context(func):
# this is a wrapper function
def wrapper(*args, **kwargs):
context_data = func(*args, **kwargs)
context_data['some_object'] = SomeObjects.objects.get(pk=1)
return context_data
return wrapper
class UpdateAnotherObjectView(BaseObjectInfo, UpdateView):
template_name = 'create_object.html'
form_class = AnotherObjectForm
model = AnotherObjects
@add_context
def get_context_data(self, **kwargs):
kwargs['all_another_objects'] = AnotherObjects.objects.all()
return kwargs
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