# MODELS

class User(models.Model):
    name = models.CharField(max_length=50)
    # ...etc...

class Assignment(models.Model):
    user = models.ForeignKey(
        settings.AUTH_USER_MODEL, on_delete=models.PROTECT
    )
    job = models.ForeignKey(Job, on_delete=models.PROTECT)
    location = models.ForeignKey(Location, on_delete=models.PROTECT)

# SERIALIZER

class UserSerializer(serializers.HyperlinkedModelSerializer):
    assignment_job = serializers.SerializerMethodField()
    multiple_locations = serializers.SerializerMethodField()
    multiple_jobs = serializers.SerializerMethodField()

    class Meta:
        model = User
        fields = [
            "url",
            "id",
            "username",
            "first_name",
            "last_name",
            "full_name",
            "email",
            "is_staff",
            "assignment_job",
            "multiple_locations",
            "multiple_jobs",
        ]

    def get_assignment_job(self, obj):
        assignment = obj.assignment_set.get(primary=True)
        return assignment.job.description

    def get_multiple_locations(self, obj):
        location_count = obj.assignment_set.filter(
            end_date__isnull=True
        ).aggregate(total_locations=Count("location"))
        if location_count["total_locations"] > 1:
            return True
        return False

    def get_multiple_jobs(self, obj):
        job_count = obj.assignment_set.filter(end_date__isnull=True).aggregate(
            total_jobs=Count("job")
        )
        if job_count["total_jobs"] > 1:
            return True
        return False