Infinite recursion with #JsonManagedReference and #JsonBackReference - spring-boot

Question

I have an entity class that is self referencing itself. For example, a document can be linked to a parent document.
#Entity
#Table(name = "documents")
public class DocumentEntity {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
#JsonIgnore
#JsonManagedReference
#ManyToOne(fetch = FetchType.LAZY)
private DocumentEntity parentDocument;
#JsonBackReference
#OneToMany(mappedBy = "parentDocument", fetch = FetchType.LAZY)
private Set<DocumentEntity> documents;
#Column(nullable = false, unique = true)
private String documentId;
#Column(nullable = false)
private String fileName;
}
In my entry point / controller layer :
#GetMapping(
path = "/{fileId}",
produces = { MediaType.APPLICATION_JSON_VALUE, MediaType.APPLICATION_XML_VALUE }
)
public DocumentResponse getParentDocument(#PathVariable("fileId") String fileId) {
modelMapper = createModelMapper();
DocumentDto documentDto = documentService.getParentDocument(fileId);
DocumentResponse documentResponse = modelMapper.map(documentDto, DocumentResponse.class);
documentResponse.getDocuments().forEach(document -> System.out.println(document.getDocumentId()));
return documentResponse;
}
In my Service layer :
#Override
public DocumentDto getParentDocument(String documentId) {
DocumentDto documentDtoResponse = new DocumentDto();
ModelMapper modelMapper = new ModelMapper();
modelMapper.getConfiguration().setMatchingStrategy(MatchingStrategies.STRICT);
DocumentEntity storedDocumentEntity =
documentRepository.findByDocumentIdAndParentDocumentNull(documentId);
if(storedDocumentEntity.getDocumentId().isEmpty() || storedDocumentEntity.getDocumentId().isBlank()) {
throw new AppFileNotFoundException("Oops file not found");
}
documentDtoResponse = modelMapper.map(storedDocumentEntity, DocumentDto.class);
return documentDtoResponse;
}
In the repository:
Now I'm making a sql request in a repository interface that extends JpaRepository.
The application allow to have a parent document with child documents and child documents cannot have child documents.
#Repository
public interface DocumentRepository extends JpaRepository<DocumentEntity, Long> {
DocumentEntity findByDocumentIdAndParentDocumentNull(String documentId);
}
I also tried to implement the method using JPQL :
#Query("SELECT d FROM DocumentEntity d WHERE d.documentId = :documentId AND d.parentDocument IS NULL")
DocumentEntity findByDocumentIdAndParentDocumentNull(String documentId);
This query allow to get parent documents and child documents.
My code implementation separates response and database by using a DTO layer.
Issue:
My issue is that I obtain an infinite recursion. I think i'm using #JsonManagedReference and #JsonBackReference correctly. Even adding the same annotations to DTO pojo do not solve issue. If i add those annotation to response POJO, then I do not obtain child documents.
Could not write JSON: Infinite recursion (StackOverflowError); nested exception is com.fasterxml.jackson.databind.JsonMappingException

Answer 1

Inially I have a DTO class that also self refers to itself.
public class DocumentDto implements Serializable {
private String filePath;
private String mimeType;
private String documentType;
private DocumentDto parentDocument;
Set<DocumentDto> documents;
}
I created a second class without properties that are causing problems;
public class DocumentChildDto implements Serializable {
private String filePath;
private String mimeType;
private String documentType;
}
In the DocumentDto I simply replaced the DocumentDto with DocumentChildDto.
public class DocumentDto implements Serializable {
private String filePath;
private String mimeType;
private String documentType;
private DocumentChildDto parentDocument;
Set<DocumentChildDto> documents;
}
It's more a hack than a technical solution but it works fine. Here childDocumentDto object won't load the parentDocument.