Updating property and resource link in single PUT query with Spring Data Rest - spring

Question

OK so let's start self referencing object, something like this:
#Data
#Entity
public class FamilyNode {
#Id
#GeneratedValue
private long id;
private boolean orphan;
#ManyToOne
private FamilyNode parent;
}
And a standard repository rest resource like this:
#RepositoryRestResource(collectionResourceRel = "familynodes", path = "familynodes")
public interface FamilyNodeRepository extends CrudRepository<FamilyNode, Long> {
}
Now, let's assume some parent objects which I want to link with already exist with ID=1 and ID=2, each of which were created with a POST to /api/familynodes which looked like this:
{
"orphan": true,
}
If I attempt to create a new client (ID=3) with something like this using a POST request to /api/familynodes, it will work fine with the linked resource updating fine in the DB:
{
"orphan": false,
"parent": "/api/familynodes/1"
}
However, if I attempt to do a PUT with the following body to /api/familynodes/3, the parent property seems to silently do nothing and the database is not updated to reflect the new association:
{
"orphan": false,
"parent": "/api/familynodes/2"
}
Similarly (and this is the use case that I'm getting at), a PUT like this will only update the orphan property but will leave the parent untouched:
{
"orphan": true,
"parent": null
}
So you now have a record which claims to be an orphan, but still has a parent. Of course you could do subsequent REST requests to the resource URI directly but I'm trying to make rest operations atomic so that it's impossible for any single rest query to create invalid state. So now I'm struggling with how do that with what seems like a simple use case without getting into writing my own controller to handle it - am I missing a mechanism here within the realm of spring data rest?

Answer 1

This is the expected behaviour for PUT requests in Spring Data Rest 2.5.7 and above wherein a PUT request does not update the resource links, only the main attributes.
As detailed here by Oliver Gierke:
If we consider URIs for association fields in the payload to update those associations, the question comes up about what's supposed to happen if no URI is specified. With the current behavior, linked associations are simply not a part of the payload as they only reside in the _links block. We have two options in this scenario: wiping the associations that are not handed, which breaks the "PUT what you GET" approach. Only wiping the ones that are supplied using null would sort of blur the "you PUT the entire state of the resource".
You may use a PATCH instead of PUT to achieve the desired result in your case