Django REST Framework serializer PrimaryKeyRelatedField() not adding object in GET response - django

Question

I'm using Django 2.x and `Django REST Framework.
I have models.py with content as
class ModeOfPayment(models.Model):
id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
title = models.CharField()
class AmountGiven(models.Model):
id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
contact = models.ForeignKey(Contact, on_delete=models.PROTECT)
amount = models.FloatField()
mode_of_payment = models.ForeignKey(
ModeOfPayment,
on_delete=models.PROTECT,
blank=True,
default=None,
null=True
)
and serializers.py
class AmountGivenSerializer(serializers.ModelSerializer):
mode_of_payment = serializers.PrimaryKeyRelatedField(queryset=ModeOfPayment.objects.all())
class Meta:
model = AmountGiven
depth = 1
fields = (
'id', 'contact', 'amount', 'mode_of_payment',
)
def update(self, instance, validated_data):
mode_of_payment = validated_data.pop('mode_of_payment')
instance.mode_of_payment_id = mode_of_payment.id
return instance
This works fine as I'm able to update mode_of_payment field. But in response when calling amount_given doesn't contain parameters of mode_of_payment object.
the response is like
{
"id": "326218dc-66ab-4c01-95dc-ce85f226012d",
"contact": {
"id": "b1b87766-86c5-4029-aa7f-887f436d6a6e",
"first_name": "Prince",
"last_name": "Raj",
"user": 3
},
"amount": 3000,
"mode_of_payment": "0cd51796-a423-4b75-a0b5-80c03f7b1e65",
}
while removing the line
mode_of_payment = serializers.PrimaryKeyRelatedField(queryset=ModeOfPayment.objects.all())
does add the mode_of_payment parameters with response but this time this does not update the mode_of_payment field on amount_given.
why mode_of_payment data is not contained even when depth is set to 1.

Answer 1

You can create ModeOfPaymentSerializer and use it in AmountGivenSerializer's to_representation() method:
class ModeOfPaymentSerializer(serializers.ModelSerializer):
class Meta:
model = ModeOfPayment
fields = (
'id', 'title',
)
class AmountGivenSerializer(serializers.ModelSerializer):
mode_of_payment = serializers.PrimaryKeyRelatedField(queryset=ModeOfPayment.objects.all())
class Meta:
model = AmountGiven
fields = (
'id', 'contact', 'amount', 'mode_of_payment',
)
def update(self, instance, validated_data):
mode_of_payment = validated_data.pop('mode_of_payment')
instance.mode_of_payment_id = mode_of_payment.id
return instance
def to_representation(self, value):
data = super().to_representation(value)
mode_serializer = ModeOfPaymentSerializer(value.mode_of_payment)
data['mode_of_payment'] = mode_serializer.data
return data