Jackson - custom serializer that overrides only specific fields

Question

I know how to use a custom serializer in Jackson (by extending JsonSerializer), but I want the default serializer to work for all fields, except for just 1 fiel

Answer 1

In case you don't want to pollute your model with annotations, you could use mixins.

ObjectMapper mapper = new ObjectMapper();
SimpleModule simpleModule = new SimpleModule();
simpleModule.setMixInAnnotation(Student.class, StudentMixin.class);
mapper.registerModule(simpleModule);

And you want to override id field for example:

public abstract class StudentMixin {
    @JsonSerialize(using = StudentIdSerializer.class)
    public String id;
}

Do whatever you need with the field:

public class StudentIdSerializer extends JsonSerializer {
    @Override
    public void serialize(Integer integer, JsonGenerator jsonGenerator, SerializerProvider serializerProvider) throws IOException {
        jsonGenerator.writeString(String.valueOf(integer * 2));
    }
}