JSON field sometimes contains string, sometimes object-CodePudding

I'm using Django rest framework to validate JSON received from an API that receives financial transactions. The serializer has been working for a few years now. The merchant field in the JSON would always contained the merchant as a nested object with the merchant's ID, name etc. But now I am sometimes receiving just the merchant's ID as a string and the JSON now fails validation.

How do I set up my serializer to allow eith string or object in the merchant field?

Basically the merchant fields needs to accept either of these:

merchant = MerchantSerializer(required=False, allow_null=True)
merchant = serializers.CharField(required=False, max_length=50)

serializers.py

class MerchantSerializer(serializers.Serializer):
    id = serializers.CharField(required=True, max_length=50)
    name = serializers.CharField(required=True, max_length=100)
    atm = serializers.BooleanField(required=False, allow_null=True)
    address = AddressSerializer(required=False, allow_null=True)
    logo = serializers.URLField(required=False, allow_null=True, max_length=500, min_length=None, allow_blank=True)

class DataSerializer(serializers.Serializer):
    account_id = serializers.CharField(required=True, max_length=50)
    amount = serializers.IntegerField(required=True)
    created = serializers.DateTimeField()
    currency = serializers.CharField(required=True, max_length=3)
    description = serializers.CharField(required=True, max_length=250)
    id = serializers.CharField(required=True, max_length=50)
    category = serializers.CharField(required=True, max_length=100)
    decline_reason = serializers.CharField(required=False, allow_null=True, allow_blank=True, max_length=100)
    merchant = MerchantSerializer(required=False, allow_null=True)
    counterparty = CounterpartySerializer(required=False, allow_null=True)
    metadata = MetadataSerializer(required=False, allow_null=True)

CodePudding user response：

You can override to_internal_value such that, it would try to parse the passed data. In the solution below, it's just checking if the data is a dictionary and set it to a dictionary if it's not.

This solution will allow the serializer to accept a string but within the serializer it will become a dictionary containing a key id only.

class MerchantSerializer(serializers.Serializer):
    id = serializers.CharField(required=True, max_length=50)
    # other fields ...

    def to_internal_value(self, data):
        parsed_data = data
        if not isinstnace(parsed_data, dict):
            parsed_data = { "id": data }
        return super().to_internal_value(parsed_data)

You will probably have to change some validations on the serializer to allow it to receive only id though.

CodePudding user response：

You need to set required to false for the name field.

class MerchantSerializer(serializers.Serializer):
    id = serializers.CharField(required=True, max_length=50)
    name = serializers.CharField(required=False, max_length=100)   # this field
    atm = serializers.BooleanField(required=False, allow_null=True)
    address = AddressSerializer(required=False, allow_null=True)
    logo = serializers.URLField(required=False, allow_null=True, max_length=500, min_length=None, allow_blank=True)

Hope it could help.