`@JsonSerialize` with `nullUsing` option not working for `String` properties

[esoni88]

Hi All,
if i use AfterModule
this.registerModule(new AfterburnerModule());

the following annotation
@JsonSerialize(nullsUsing=CustomSerialize.class)

not work.
How can enable it ? i want to customize null serialization for certain fields.
Thanks
Dario

[cowtowncoder]

@dario-frongillo It should just work. If not, it would be great to have a unit test that shows the problem so we can fix it.

[esoni88]

Hi @cowtowncoder ,
this is a a simple spring boot app that show you the issue: https://github.com/dario-frongillo/test-null-serializer-afterburnerModule

I customized the object mapper in order to use AfterburnerModule

@Component
@Primary
public class CustomObjectMapper extends ObjectMapper {
    public CustomObjectMapper() {
        // if you comment this instruction the  NULL field with annotation  
 //@JsonSerialize(nullsUsing=MyNullSerializer.class)
        // are correctly serialized with MyNullSerializer
        this.registerModule(new AfterburnerModule());
        disable(DeserializationFeature.ADJUST_DATES_TO_CONTEXT_TIME_ZONE);
    }
}

I have a model Person with certain fields with annotation :@JsonSerialize(nullsUsing=MyNullSerializer.class)

for i.e

    @JsonSerialize(nullsUsing=MyNullSerializer.class)
    private String c;

I have a simple controller to test it with a curl tool as postman

    @RequestMapping("/greeting")
    public ResponseEntity<?> getProva(){
        Person a = new Person();
        a.setA("x");
        a.setB(null);
        a.setC(null);
        return ResponseEntity.ok(a);
    }

the controller return c field with null so MyNullSerializer should intercept the serialization but this does not happen.
If i comment the instruction

this.registerModule(new AfterburnerModule());`

on my object mapper all it works.. so AfterburnerModule not allow you to use null serializer.. can you kindly check it ?
Thanks a lot
Dario

[cowtowncoder]

Ok I'll try to create stand-alone test (it makes no sense to add Spring Boot dependency for unit tests) and may be able to resolve this. Afterburner should not change behavior in any way here.

[cowtowncoder]

Thank you for reporting this -- this turned out to specifically affect String valued properties, since they are optimized separately (along with int, long and boolean); and being the only Object value (as opposed to primitive) was missing one check that "general Object-valued" handler was doing.

Fix will be in 2.9.3 but I also back-ported it in 2.8 branch in case 2.8.11 might be released at some point.