Error

AssertionError: The `.create()` method does not support writable dotted-source fields by default.
Write an explicit `.create()` method for serializer `hrm_apps.configuration.serializers.CurrencySerializer`, or set `read_only=True` on dotted-source serializer fields.

models.py,

class CurrencyMaster(models.Model):
    code = models.CharField(max_length=3, null=False, unique=True)
    name = models.CharField(max_length=100, null=False, unique=True)

    def __str__(self):
        return self.name
class Currency(models.Model):
    currency_master = models.OneToOneField(CurrencyMaster, on_delete=models.RESTRICT)
    conversion_rate = models.FloatField(null=False)

    def __str__(self):
        return self.currency_master.name

views.py,

class CurrencyViewSet(viewsets.ModelViewSet):
    queryset = Currency.objects.all()
    serializer_class = CurrencySerializer
    lookup_field = 'id'

serializers.py,

class CurrencySerializer(serializers.ModelSerializer):
    currency_master = serializers.CharField(source="currency_master.name")

    class Meta:
        model = Currency
        fields = ['id', 'currency_master', 'conversion_rate']

When i give post request i got assertion error like above,

class CurrencySerializer(serializers.ModelSerializer):
    currency_master = serializers.CharField(source="currency_master.name")

    class Meta:
        model = Currency
        fields = ['id', 'currency_master', 'conversion_rate']

    def create(self, validated_data):
        return Currency.objects.create(**validated_data)

    def update(self, instance, validated_data):
        instance.currency_master = validated_data.get('currency_master', instance.currency_master)
        instance.conversion_rate = validated_data.get('conversion_rate', instance.conversion_rate)
        return instance

I tried above i got this error "ValueError: Cannot assign "{'name': 'ALL - Albania Lek'}": "Currency.currency_master" must be a "CurrencyMaster" instance". How to resolve this???

CodePudding user response：

Customize the create method.

class CurrencySerializer(serializers.ModelSerializer):
    currency_master = serializers.CharField(source="currency_master.name")

    class Meta:
        model = Currency
        fields = ['id', 'currency_master', 'conversion_rate']

    def create(self, validated_data):
        currency_master_name = validated_data.pop('currency_master')["name"]
        currency_master_obj = get_object_or_404(CurrencyMaster, name=currency_master_name)
        validated_data["currency_master"] = currency_master_obj
        return Currency.objects.create(**validated_data)