How to associate an object with inheritance in Spring Data REST when sending a new object?

Question

I have entities with combined inheritance:

Supporter

@Entity @Inheritance(strategy=InheritanceType.JOINED) @JsonTypeInfo(use = JsonTypeInfo.Id.NAME, include = JsonTypeInfo.As.PROPERTY, property = "supporterType") @JsonSubTypes({ @JsonSubTypes.Type(value = PersonSupporterEntity.class, name = "PERSON"), @JsonSubTypes.Type(value = CompanySupporterEntity.class, name = "COMPANY") }) @DiscriminatorColumn(name="supporter_type") @Table(name = "supporter") public class SupporterEntity extends UpdatableEntity { private long id; private SupporterType supporterType; private PartnerEntity partner; ... } 

PersonSupporter

 @Entity @DiscriminatorValue("PERSON") @Table(name = "person_supporter") public class PersonSupporterEntity extends SupporterEntity { ... } 

Companysupporter

 @Entity @DiscriminatorValue("COMPANY") @Table(name = "company_supporter") public class CompanySupporterEntity extends SupporterEntity { ... } 

I have another object that references SupporterEntity

 @Entity @Table(name = "contact") public class ContactEntity extends UpdatableEntity { private long id; private SupporterEntity supporter; ... @ManyToOne // same error with @OneToOne @JoinColumn(name = "supporter_id", referencedColumnName = "id", nullable = false) public SupporterEntity getSupporter() { return supporter; } ... } 

Storage facilities

 @Transactional @RepositoryRestResource(collectionResourceRel = "supporters", path = "supporters") public interface SupporterEntityRepository extends JpaRepository<SupporterEntity, Long> { @Transactional(readOnly = true) @RestResource(path = "by-partner", rel = "by-partner") public Page<SupporterEntity> findByPartnerName(@Param("name") String name, Pageable pageable); } 

 @Transactional @RepositoryRestResource(collectionResourceRel = "person_supporters", path = "person_supporters") public interface PersonSupporterEntityRepository extends JpaRepository<PersonSupporterEntity, Long> { } 

 @Transactional @RepositoryRestResource(collectionResourceRel = "company_supporters", path = "company_supporters") public interface CompanySupporterEntityRepository extends JpaRepository<CompanySupporterEntity, Long> { } 

 @Transactional @RepositoryRestResource(collectionResourceRel = "contacts", path = "contacts") public interface ContactEntityRepository extends JpaRepository<ContactEntity, Long> { @Transactional(readOnly = true) @RestResource(path = "by-supporter", rel = "by-supporter") public ContactEntity findBySupporterId(@Param("id") Long id); } 

I use Spring Boot, Spring Data REST, Spring Data JPA, Hibernate, Jackson. When I try to create a new ContactEntity with an email request as follows:

 { "supporter":"/supporters/52", "postcode":"1111", "city":"Test City 1", "address":"Test Address 1", "email":" [e-mail] ", "newsletter":true } 

I get this exception:

 Caused by: com.fasterxml.jackson.databind.JsonMappingException: Unexpected token (VALUE_STRING), expected FIELD_NAME: missing property 'supporterType' that is to contain type id (for class com.facer.domain.supporter.SupporterEntity) at [Source: HttpInputOverHTTP@4321c221 ; line: 1, column: 2] (through reference chain: com.facer.domain.supporter.ContactEntity["supporter"]) at com.fasterxml.jackson.databind.JsonMappingException.from(JsonMappingException.java:148) ~[jackson-databind-2.4.4.jar:2.4.4] 

After two days of debugging, I found a way, but I kind of figured it out. Therefore, if I publish it as follows:

 { "supporter":{ "supporterType":"PERSON", "id":"52" }, "postcode":"1111", "city":"Test City 1", "address":"Test Address 1", "email":" [e-mail] ", "newsletter":true } 

It works, but I don’t know why. What is wrong with another request? It works just like everywhere else when the reference object has no inheritance.

Answer 1

This is similar to Jackson's problem. To be specific, this is 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 will be called, which in turn runs some Spring code to convert the URI to Supporter .

With the inheritance, _valueDeserializer.deserializeWithType is invoked and Vanilla Jackson, of course, expects an object, not a URI.

If Supporter is NULL, you can first POST to /contacts , and then PUT URI support to /contacts/xx/supporter . Unfortunately, I do not know another solution.

Answer 2

Another workaround using RelProvider :

• Do not use @JsonTypeInfo

• Subclass RelProvider for SupporterEntity

   @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

Answer 3

You should be able to get around this by setting @JsonTypeInfo (use = JsonTypeInfo.Id.NONE) at the property / method level, for example.

Try the following:

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