How to relate two tables with one of the field equal? - django

Question

I am new with django and django rest framework. Excuse me for my bad english...
I am trying to relate two django models:
First one (class ModulMess) receives messages from remote numbered modules
-moduleA received message "AAA".
-moduleB received message "BBB"
-moduleA received message "CCC"
-moduleC received message "DDD"
Second one (class Owner) is a list of users who own the modules
-UserXX owns moduleA and moduleC
-UserYY owns moduleB
I am tryng to make search filter in order to list this sort of message for actual user:
For example, for UserXX:
UserXX received from moduleA messages "AAA" and "CCC"
and from moduleC message "DDD"
Please could you explain me theorically how to manage it? I am not abble to visualize how to make relations between the two models, as they have one equal field each one...
Thank you very much!
I tried:
class Owner(models.Model):
user = models.ForeignKey(User, on_delete=models.CASCADE,related_name='usermod')
modulkey = models.CharField(max_length=255)
date_in = models.DateTimeField(default=timezone.now, blank=True)
def __str__(self):
return f'{self.user.first_name} {self.user.last_name} | {self.modulkey}'
class ModulMess(models.Model):
modulkey = models.ForeignKey(Owner, on_delete=models.CASCADE)
date_ini = models.DateTimeField(default=timezone.now, blank=True)
message = models.CharField(max_length=255)
But cannot reach to achieve a good serializer nor view...

Answer 1

I think your modelling is correct. You also need the correct queryset logic and you are set to go. But I'll try to provide the viewset and serializer.
Though the FK modulkey in ModuleMess model can be changed to owner as it makes more sense:
class ModulMess(models.Model):
owner = models.ForeignKey(Owner, on_delete=models.CASCADE)
date_ini = models.DateTimeField(default=timezone.now, blank=True)
message = models.CharField(max_length=255)
The query logic can be defined in a different function like below:
def get_messages_for_user(user):
# Get the owner object for the user
owner = Owner.objects.get(user=user)
# Filter the ModulMess queryset to include only messages for the user's modulkey
messages = ModulMess.objects.filter(owner__modulkey=owner.modulkey)
return messages
Then for serializer we can use model serializer class. Like below:
class ModulMessSerializer(serializers.ModelSerializer):
class Meta:
model = ModulMess
fields = ['id', 'date_ini', 'message', 'owner']
And lastly the viewset will look like below:
class ModulMessViewSet(viewsets.ViewSet):
permission_classes = [IsAuthenticated]
serializer_class = ModulMessSerializer
def list(self, request):
user = request.user
messages = get_messages_for_user(user)
serializer = self.serializer_class(messages, many=True)
return Response(serializer.data)