I was trying to use Jackson to write a class value to JSON that has Optional as fields:
public class Test {
Optional<String> field = Optional.of("hello, world!");
public Optional<String> getField() {
return field;
}
public static void main(String[] args) throws JsonProcessingException {
ObjectMapper mapper = new ObjectMapper();
System.out.println(mapper.writeValueAsString(new Test()));
}
}
When executed, this class generates the following output:
{"field":{"present":true}}
I understand the present/not present field being included and could work around it when reading the JSON data, however I can't get around the fact that the actual content of the optional is never written to the output. :(
Any workarounds here except not using ObjectMapper at all?
You could use jackson-datatype-jdk8 which is described as:
Support for new JDK8-specific types, such as Optional
In order to do this:
com.fasterxml.jackson.datatype:jackson-datatype-jdk8
as a dependencyobjectMapper.registerModule(new Jdk8Module());