Spring data-rest: set null value by PATCH request

Question

I want to set null value to entity by sending null request.

For example:

PATCH: "{deleteDate: null}" to http://localhost/api/entity/1

But it doesn't work.

I found here information how PATCH requests processed:

• An new instance of Foo is created
• Foo is populated with all values that have been sent with the request
• The Foo entity with the id provided by the URI is loaded
• All properties that differ between the two objects are copied from the new Foo to the persisted Foo, unless the value is null in the new Foo.

Do I understand correctly that it is impossible to set value to NULL with PATCH request to spring-data-rest service API?

Answer 1

In Spring context null values in PATCH method means that there are no changes. If you want write null values you can

1) use PUT method;
2) implement your own DomainObjectMerger class, in which you can extend method merge with condition like

sourceValue != targetValue;

3) use DomainObjectMerger.NullHandlingPolicy configuration.
Depends on your Spring Data REST version.

Answer 2

All 3 options from egorlitvinenko's answer will solve the described problem but will have another one:

• All other properties which were not specified in PATCH request would be "nullified" too.

Seems like spring-data-rest, issue-345 was already fixed in v2.2.x.