Django access queryset variabile from a custom method on the same view - django-views

Question

I am implementing csv export on django. In particular I have a link on my template to export actual query and for this I am trying to handle all on the same class based view.
Here is my code
# views.py
class MyView(ListView):
template_name = 'my_template.html'
model = Archivio
def get_queryset(self):
if self.request.GET.get('q'):
dateC = '01/01/'+self.request.GET.get('q')
queryset = Archivio.objects.filter(~Q(quoteiscrizione__anno_quota__exact=self.request.GET.get('q'))
return queryset
# my custom method
#staticmethod
def csv_output():
qs = MyView.get_queryset(): # i want to access to the queryset variable from get_queryset() method of the class
# here i have other code to produce csv output
But the method csv_output() is wrong.. I get this TypeError: csv_output() takes 0 positional arguments but 1 was given
I have also tried with a classmethod decorator but without success.
My question is: How can i access queryset variable from another method of the same class?

Answer 1

Note the self in get_queryset(self). It means the first argument of this method is always the instance of the class (in your case, MyView). So when you want to call it in another method, you should provide this instance.
The solution is to replace your #staticmethod decorator with the #classmethod one:
class MyView(ListView):
template_name = 'my_template.html'
model = Archivio
def get_queryset(self):
if self.request.GET.get('q'):
dateC = '01/01/' + self.request.GET.get('q')
queryset = Archivio.objects.filter(~Q(quoteiscrizione__anno_quota__exact=self.request.GET.get('q'))
return queryset
#classmethod
def csv_output(cls):
qs = cls.get_queryset(cls)
# Class methods have one required positional argument
# which is the class that contains them
# They are called like this:
# MyClass.class_method()
# So in your case, you can call
# get_queryset() by doing MyView.get_queryset()
# But as you are in a class method, you do
# cls.get_queryset()
# As get_queryset() needs one positional argument *self*,
# which is the instance of your class, you do
# cls.get_queryset(cls)
# and it will work as expected :-)

Answer 2

I solved my Issue saving my queryset on the request and then using it somewhere on my views like this:
views.py
class SomeClass(ListView):
def get_queryset(self):
.....
queryset = MyModel.objects.filter(*somefilterlist)
self.request.session['search_queryset'] = serialize('json', queryset) # in order to save something on session in must be JSON serialized
class Output(SomeClass):
#classmethod
def cvsOutput(cls):
deserialized = list(deserialize('json', request.session.get('search_queryset')))
pk_list = []
for arch in deserialized:
pk_list.append(arch.object.pk) # List of pk
queryset = Archivio.objects.filter(pk__in=pk_list) # Query the list ok pk's
In this way I was able to make available the list ok pk of the queryset of my ListView, then I make again the same query based on that list of pk's..