How to define optional json field using Jackson

Question

I have an object with one optional field and can not find proper annotation to model it. Any ideas what is the proper way to do it with Jackson?

Answer 1

In Jackson you cannot make the difference between optional and non-optional fields. Just declare any field in your POJO. If a field is not present in your JSON structure then Jackson will not call the setter. You may keep track of wether a setter has been called with a flag in the POJO.

Answer 2

Coming late to the party...

Using Jackson 2.8.6 via Spring HttpMessageConverter 4.3.6, I had to change my setter parameter to the unwrapped type, like so:

class Foo {     private Optional<Bar> bar;      public void setBar(Bar bar) { // NOT Optional<Bar>, this gives me Optional.empty()         this.bar = Optional.of(bar);     }      // getter doesn't need to be changed }