How to reference an entity with inheritance in Spring Data REST when POSTing new entity?

Question

I have entities with joined inheritance:

Supporter

@Entity
@Inheritance(strategy=InheritanceType.JOINED)
@Js         


        

Answer 1

You should be able to workaround this by setting @JsonTypeInfo(use= JsonTypeInfo.Id.NONE) at the property/method level e.g.

Try with this:

@ManyToOne // same error with @OneToOne
@JoinColumn(name = "supporter_id", referencedColumnName = "id", nullable = false)
@JsonTypeInfo(use= JsonTypeInfo.Id.NONE)
public SupporterEntity getSupporter() {
    return supporter;
}

Answer 2

It looks like a Jackson problem. To be specific, it's the following code in com.fasterxml.jackson.databind.deser.SettableBeanProperty:

if (_valueTypeDeserializer != null) {
   return _valueDeserializer.deserializeWithType(jp, ctxt, _valueTypeDeserializer);
}
return _valueDeserializer.deserialize(jp, ctxt);

Without inheritance _valueDeserializer.deserialize would be called which in turn runs some Spring code to convert the URI to a Supporter.

With inheritance _valueDeserializer.deserializeWithType is called and vanilla Jackson, of course, expects an object, not a URI.

If supporter was nullable you could first POST to /contacts and then PUT the supporter's URI to /contacts/xx/supporter. Unfortunately I am not aware of any other solution.

Answer 3

Just another workaround using a RelProvider:

1. Do not use @JsonTypeInfo

2. Create a RelProvider for SupporterEntity sub-classes

   @Component
   @Order(Ordered.HIGHEST_PRECEDENCE)
   public class SupporterEntityRelProvider implements RelProvider {
   
     @Override
     public String getCollectionResourceRelFor(final Class<?> type) {
       return "supporters";
     }
   
     @Override
     public String getItemResourceRelFor(final Class<?> type) {
       return "supporter";
     }
   
     @Override
     public boolean supports(final Class<?> delimiter) {
       return org.apache.commons.lang3.ClassUtils.isAssignable(delimiter, SupporterEntity.class);
     }
   }
   

See also:

• https://jira.spring.io/browse/DATAREST-344
• http://docs.spring.io/spring-hateoas/docs/current/reference/html/#configuration.at-enable