Registration of JsonbAdapter on target class

[dblevins]

The proposal is to update Jakarta JSON Binding 3.0 section 4.7.1. Adapters so that an adapter can be registered on the adapted class itself. For example:

@JsonbTypeAdapter(EmailAddressAdapter.class)
public class EmailAddress {

    private String value;

    public EmailAddress(String value) {
        this.value = value;
    }

    public String getValue() {
        return value;
    }
}

And

public class EmailAddressAdapter implements JsonbAdapter<EmailAddress, String> {

    @Override
    public String adaptToJson(EmailAddress obj) {
        return obj.getValue();
    }

    @Override
    public EmailAddress adaptFromJson(String obj) {
        return new EmailAddress(obj);
    }
}

For the purposes specification backwards compatibility and the ability to override an adapter, the existing two forms would take precedence. This is consistent with the specification's requirement use of JsonbTypeAdapter on parameters be ignored if it the adapter is defined on a field or in the config.

[dblevins]

See also #340 by @mkarg

[dblevins]

🔍 Implementation Behavior of @JsonbTypeAdapter Annotation on Class

Implementation	Version	Write (Serialize)	Read (Deserialize)	Notes
Yasson	3.0.3	✅ Works	✅ Works	Fully honors @JsonbTypeAdapter on class
Johnzon	2.0.1	✅ Works	⚠️ Only works if previously serialized	Adapter not discovered during read unless previously cached

[dblevins]

Sample project with both Yasson and Johnzon: https://github.com/tomitribe/jsonbadapter

[jungm]

+1

There is also a similar issue for JsonbTypeDeserializer/JsonbTypeSerializer (#89), it is about inconsistent specs but roughly the same underlying issue

[mkarg]

+1

[Verdent]

+1