Django REST ManyToManyField fetch related values using serializer

Question

I am new to django. I had searched all over stackoverflow but did get anything related.

I had two Table Owner and Services. owner can select N no of services. I am using ManyToManyField and i want to fetch related values in Generic View. may be it can be achieved using prefetch_related function but i dont know how. I want output like below. can anyone please help me achieving below expected output. Thanks

Expected Output

[
    {
        "owner_id": 1,
        "first_name": "james",
        "last_name": "cook",
        "services_id": [
               [1, service_title, desc],
               [2, service_title, desc],
               [3, service_title, desc]
        ]
    }
]

model.py

class services(models.Model):   
   service_id=models.IntegerField(primary_key=True)
   title=models.CharField(max_length=200)
   description=models.TextField()
   type=models.PositiveSmallIntegerField() #1: Package; 2: A La Carte
   status=models.PositiveSmallIntegerField(default=1)

class reservations(models.Model):
   owner_id=models.IntegerField()
   first_name=models.CharField(max_length=50)
   last_name=models.CharField(max_length=50)
   services_id=models.ManyToManyField(services, related_name='services')

serializers.py

class servicesSerializer(ModelSerializer):
    class Meta:
        model=services
        fields = [
            'service_id'
            'title',
            'description',
            'type',
        ]


class ownerSerializer(ModelSerializer):
    class Meta:
        model=reservations
        fields = [
        'owner_id',
        'first_name',
        'last_name',
        'services_id',
        ]

View.py

class upcomingServices(ListAPIView):
 queryset = owner.objects.all()
 serializer_class=ownerSerializer

output

[
{
    "owner_id": 1,
    "first_name": "james",
    "last_name": "cook",
    "services_id": [
        1,
        2,
        3
    ]
}
]

Answer 1

I changed the view slightly as below,

class upcomingServices(ListAPIView):
    queryset = reservations.objects.all()  # Changed here
    serializer_class = ownerSerializer

Change your serializer.py as below,

class servicesSerializer(serializers.ModelSerializer):
    class Meta:
        model = services
        fields = ['service_id'
                  'title',
                  'description',
                  'type',
                  ]

    def to_representation(self, instance):
        return [instance.service_id, instance.title, instance.description]


class ownerSerializer(serializers.ModelSerializer):
    services_id = servicesSerializer(many=True)

    class Meta:
        model = reservations
        fields = [
            'owner_id',
            'first_name',
            'last_name',
            'services_id',
        ]

Answer 2

Use this in your ServicesSerializer

class servicesSerailizer(ModelSerializer):
        class Meta:
            model=services
            fields = [
                'service_id'
                'title',
                'description',
                'type',
            ]

        def to_representation(self, value):
            return [value.pk, value.title, value.description]

and add it to your ownerSerializer

class ownerSerializer(reservationSerailizer):
    service_id = servicesSerializer(many=True, read_only=True)
    class Meta:
        model=reservations
        fields = [
            'owner_id',
            'first_name',
            'last_name',
            'services_id',
             ]

Here the docs