send request from signal - django

Question

I have an exam model that whenever an instance is created, instances of the Question model to the number that is specified in the Exam are created(using post_save signal). Also, I have a Go code that whenever a request is sent, fills out 3 fields of the Question model. My problem is how can I send this request in the signal part.
The codes are as followed:
models.py:
class Exam(models.Model):
title = models.CharField(max_length=255)
subject = models.CharField(max_length=255, default='')
organizer = models.CharField(max_length=255, default='...')
description = models.TextField(max_length=1000)
created_at = models.DateTimeField(auto_now_add=True)
duration = models.DurationField()
number_of_questions = models.PositiveSmallIntegerField()
order = models.IntegerField(default=0)
def __str__(self):
return self.title
class ExamQuestion(models.Model):
exam = models.ForeignKey('ExamApply', on_delete=models.CASCADE)
question_template = models.ForeignKey(QuestionTemplate, on_delete=models.CASCADE)
text = models.TextField(max_length=5000, null=True, blank=True)
question_params = models.JSONField(null=True, blank=True)
answer_choices = models.JSONField(null=True, blank=True)
answer_given = models.JSONField(default=dict, null=True, blank=True)
correct_answer = models.JSONField(null=True, blank=True)
data = models.JSONField(null=True, blank=True)
is_correct = models.BooleanField(null=True)
order = models.IntegerField(null=True, blank=True)
def __str__(self):
return str(self.id)
class ExamApply(models.Model):
class Status(models.TextChoices):
CREATED = 'CR', 'Created'
STARTED = 'ST', 'Started'
FINISHED = 'FN', 'Finished'
user = models.ForeignKey(settings.AUTH_USER_MODEL, on_delete=models.CASCADE)
exam = models.ForeignKey(Exam, on_delete=models.CASCADE)
start_date = models.DateTimeField()
end_date = models.DateTimeField()
status = models.CharField(max_length=2, choices=Status.choices, default=Status.CREATED)
def get_score(self):
score = ExamQuestion.objects.filter(exam=self, answer_given=F('correct_answer')).count()
return score
signals.py:
#receiver(post_save, sender=ExamApply)
def create_examapply_examquestion(sender, instance, created, **kwargs):
if created:
for _ in range(instance.exam.number_of_questions):
ExamQuestion.objects.create(exam=instance)
id = ExamQuestion.objects.all().last().id
return redirect('/question/' + str(id) + '/') #doesnt work
#receiver(post_save, sender=ExamApply)
def save_examapply_examquestion(sender, instance, created, **kwargs):
instance.exam.save()
urls.py related to the part I want:
urlpatterns = [
path('questions/<int:pk>/', UpdateQuestionAPI.as_view()),
]
views.py:
class UpdateQuestionAPI(generics.RetrieveUpdateDestroyAPIView):
queryset = ExamQuestion.objects.all()
serializer_class = IntegrateQuestionSerializer
lookup_field = 'pk'
def get(self, request, *args, **kwargs):
question = ExamQuestion.objects.filter(pk=kwargs['pk'])
serializer = ExamQuestionSerializer(question, many=True)
return Response(serializer.data)
def update(self, request, *args, **kwargs):
instance = self.get_object()
serializer = self.get_serializer(instance, data=request.data, partial=True)
if serializer.is_valid():
serializer.save()
return Response({"message": "updated successfully"})
else:
return Response({"message": "failed", "details": serializer.errors})
serializers.py:
class IntegrateQuestionSerializer(serializers.ModelSerializer):
class Meta:
model = ExamQuestion
fields = ['question_params', 'answer_choices', 'correct_answer',]
class ExamQuestionSerializer(serializers.ModelSerializer):
title = serializers.SerializerMethodField()
class Meta:
model = ExamQuestion
fields = ['title']
def get_title(self, obj):
return obj.exam.exam.title
I had the idea of using redirect(to the update view), but it doesn't work.

Answer 1

First of all, it makes no sense to use request in the signal part.
This code is related to the model and the orm and is not responsible of the request part. That's the view work.
The signal you are using is related to the creation of the ExamApply model. The view you posted doesn't create a ExamApply so it will not get called at all.
Just so you know, usually signals are avoided because they lead to complicated code. To quote the documentation “Signals give the appearance of loose coupling, but they can quickly lead to code that is hard to understand, adjust and debug. Where possible you should opt for directly calling the handling code, rather than dispatching via a signal.”
Here you have multiple issues in your signals, you have a return in a loop, that will stop the loop after the first iteration. Then you return an HttpResponse (in the form of redirect) but you are not in a view so it doesn't make sense.
It's not clear what you want to do because the view and the serializer you posted are not related to the creation of ExamApply as I understand it what you could do (one of):
Override the save method of ExamApply to create the questions.
Or handle the creation of questions in the view that create the ExamApply
For example:
def save(self, *args, **kwargs):
if not self.pk:
# not self.pk means a creation.
for _ in range(self.exam.number_of_questions):
question = ExamQuestion.objects.create(exam=self.exam)
# You might want to link question to user / exam apply here?
self.exam.question_set.add(question)
super().save(*args, **kwargs)
In your ExamApply creation view or serializer you might want to return the questions id, if you use DRF it's trivial to do so: https://www.django-rest-framework.org/api-guide/relations/#primarykeyrelatedfield
But you might want to link questions to ExamApply and/or user and not just Exam.
On a side note, for the future, if you need the created object id you should use
question = ExamQuestion.objects.create(exam=instance)
question.id