Deserializing a number that is null throws

[aubergemediale]

When I deserialize json that contains

{"address":"an address","amount":null}

to a target Type like

public class Recipient
    {
        public string Address { get; set; }
        public long Amount { get; set; }
    }

I get an Exception: expected:'Number Token', actual:'null', at offset:107

My expectation would be, that the long gets initialized to its default value of 0;

Afaik, in json or javascript, it is not wrong to have a number be null. It's just a falsy value.

And I think the least surprise would be if this would not throw and just set the number to 0.

Is there maybe any option I can use to achieve this? This is not so easy to fix if you don't have control of the production of the json you are getting.

[tandasima]

Deserializer is expecting a number long (number) primitive type but you are giving it a null. You should make Amount nullable as in public long? Amount { get; set; }

Also, deserializing a null to 0 doesn't make sense since 0 and null are essentially 2 different values when dealing with primitive types hence ? nullable feature.

If there is not any Amount, just don't pass it in the payload and it'll default to 0. However, if you make it ? nullable it will be null when you don't pass it.

[aubergemediale]

@tandasima I can't agree with you here. Sure, I could work around this with making the long a Nullable and then write extra code to query .HasValue. But that is complicated and not efficient. We want extreme perf, here don't we? :-)

Also, I cannot influence what the api is getting as Json. I am getting:

• no property 'amount'
• amount: null
• amount: 0

JSON null means: also undefined, NaN, +/- infinity, it doen't strictly equal C# null.

So, imo, the C# property should basically 'stay' it's default value of 0, because no better value can be assigned.

Also, Newtonsoft's and Microsofts new serializers do it this way.

So I hope I find a way with Utf8Json to have the null resolve to 0. Maybe there is a way to override or customize this behavior, but I can't find that in the documentation...