Differentiate a null value from an absent one in JsonDeserializer #578
Description
Hi,
I have a class representing a field update:
public class OptionalUpdate<T> { private final Optional<T> value; private Present(Optional<T> value) { this.value = value; } public boolean isPresent() { return value != null; } public Optional<T> getValue() { return value; } public static <T> OptionalUpdate<T> unset() { return new OptionalUpdate<>(Optional.empty()); } public static <T> OptionalUpdate<T> set(T value) { return new OptionalUpdate<>(Optional.of(value)); } public static <T> OptionalUpdate<T> empty() { return new OptionalUpdate<>(null); } }and an entity update:
public class UserUpdate { private final OptionalUpdate<String> nickname; @JsonCreator public UserUpdate(OptionalUpdate<String> nickname) { this.nickname = nickname; } public OptionalUpdate<String> getNickname() { return nickname; } }I would like to handle three types of updates:
- to set a nickname to "lolcontrol":
{ "nickname": "lolcontrol" } - to unset a nickname:
{ "nickname": null } - not to update a nickname:
{ }
How relevant is it to add a new method to JsonDeserializer that can be overridden in the custom deserializer?
/** * Method called to determine value to be used for absent values. * Usually this is same as {@link #getNullValue} (which in turn * is usually simply Java null), but it can be overridden * for types. *<p> * Default implementation simple calls {@link #getNullValue} and * returns value. */ public T getAbsentValue() { return getNullValue(); }