Add warning message in django-rest-framework - django

Question

I am new to django-rest-framework. I am building an employee scheduling application where I have a REST Api built with drf and frontend in angular. Below is one of my models and it's corrsponding serializer and viewset.
model:
class Eventdetail(models.Model):
event = models.ForeignKey(Event, models.DO_NOTHING, blank=True, null=True)
start = models.DateTimeField(blank=True, null=True)
end = models.DateTimeField(blank=True, null=True)
employee = models.ForeignKey(Employee, models.DO_NOTHING, blank=True, null=True)
location = models.ForeignKey(Location, models.DO_NOTHING, blank=True, null=True)
is_daily_detail = models.BooleanField
def __str__(self):
return self.event
serializer:
class LocationTrackSerializer(serializers.ModelSerializer):
def __init__(self, *args, **kwargs):
many = kwargs.pop('many', True)
super(LocationTrackSerializer, self).__init__(many=many, *args, **kwargs)
location = serializers.SlugRelatedField(slug_field='location_name', queryset=Location.objects.all())
location_color = serializers.CharField(source='location.location_color', read_only=True)
class Meta:
model = Eventdetail
fields = ('id','employee','location','location_color','start','end')
viewset:
class LocationTrackViewSet(viewsets.ModelViewSet):
queryset = Eventdetail.objects.all()
serializer_class = LocationTrackSerializer
def create(self, request, *args, **kwargs):
self.user = request.user
listOfThings = request.data['events']
serializer = self.get_serializer(data=listOfThings, many=True)
if serializer.is_valid():
serializer.save()
headers = self.get_success_headers(serializer.data)
return Response(serializer.data, status=status.HTTP_201_CREATED,
headers=headers)
return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)
As you can see, this exposes event details of all employees. Now when new events are posted, I want to be able to find if the start and end times of posted events overlap with existing events and throw a warning message with info of overlapping events after creation. I still want to allow save but only return warnings after save. i am trying to figure out a way to do this. I looked at how to create validators, but I am not sure if that is how I should go about this. Any help is appreciated! Thanks.

Answer 1

You can add a field warning_message to the serializer as follows -
class LocationTrackSerializer(serializers.ModelSerializer):
# rest of the code
def get_warning_message(self, obj):
warning_msg = ''
# logic for checking overlapping dates
# create a method `are_dates_overlapping` which takes
# start and end date of the current obj and checks with all
# others in queryset.
overlap = are_dates_overlapping(obj.start, obj.end)
if overlap:
warning_msg = 'overlaps'
return warning_msg
warning_message = serializers.SerializerMethodField(read_only=True)
class Meta:
model = Eventdetail
fields = ('id','employee','location','location_color','start','end', 'warning_message')
Ref: Serializer Method Field in DRF