I'm newbie in django and I was trying to construct a site in which the user can take a quiz. In a simpler version of that, I wanted just the questions to be displayed in random order, one after another(when the user presses a button) and when all the questions have been displayed to return to the main page, where there is a link "take the test". I know that it certainly isn't the most efficient way to do it, but I want to know what is wrong with my code.

urls.py:

path('start',views.startquiz,name='start'),
path('test/<int:pk>/<int:index>',views.TakeQuizView.as_view(),name='test'),

views.py:

def startquiz(request):
    questions=list(Question.objects.all())
    question=random.choice(questions)
    pk=question.id
    return redirect(reverse('quiz:test',args=(pk,1)))

class TakeQuizView(LoginRequiredMixin,View):
    questions=list(Question.objects.all())
    n=len(questions)

    def get(self,request,pk,index):
        question=Question.objects.get(id=pk)
        self.questions.remove(question)
        ctx={'question':question,'index':index,'n':self.n}
        return render(request,'quiz/test.html',ctx,)

    def post(self,request,pk,index):
        if index<self.n:
            question=random.choice(self.questions)
            pk=question.id
            return redirect(reverse('quiz:test',args=(pk,index 1)))
        else:
            self.questions=list(Question.objects.all())
            return redirect(reverse_lazy('quiz:main'))

` Whenever I take the quiz for the first time, all works fine, and after all questions have been displayed, it returns to the main page. However, if I want to take the test again, the questions list fails to be filled up again and I get an error: list.remove(x): x not in list from remove()

I also tried to put in the get method the following code: `

if index==1:
    self.questions=list(Question.objects.all())

` However it still does not work and I have some unexpected results. When I try to restart the quiz, I have the list filled up, and on the second step it suddenly gets emptied and I really cannot figure out what's going wrong.

CodePudding user response：

The problem with your approach is that HTTP is stateless. Each request should have all the information required for the server to handle it. In other words the server should absolutely not keep any state. In your case, the questions list represents a state.

More details about HTTP and its statelessness: Why is it said that "HTTP is a stateless protocol"?

Instead of keeping a list of your questions on the server side you should randomly pull a question at each request from the client. How to pull a random record using Django's ORM?

To make sure that the same questions does not appear twice there are multiple possible solutions:

1. the client should send the ids of the seen questions (perhaps by get Query parameters) when asking for a new question.
2. the client stores a session_id and sends that to the server with every request. The server then stores in a table the mapping between a session id and the question that were displayed so far.
3. cookies might represent a solution as well, but I would say it's the most complicated out of the 3

Personally I would go with the first solution.