Spring Boot methods to add and remove relationships

Question

I have a Spring Boot application and I wrote a piece of code to manage relationships between two entities.

The code consists mostly in these two methods:

@Override
 public void associateDocumentsToPersonRecord(Long personRecordId, AssociationDTO associationDTO) {
 PersonRecord personRecord = personRecordRepository.findById(personRecordId).orElse(null);
 if (personRecord == null)
 return;
 for (Long documentId : associationDTO.getDocumentsId())
 documentRepository
 .findById(documentId)
 .ifPresent(document -> personRecord.getDocuments().add(document));
 personRecordRepository.save(personRecord);
 }
 @Override
 public void removeAssociateDocumentsToPersonRecord(Long personRecordId, AssociationDTO associationDTO) {
 PersonRecord personRecord = personRecordRepository.findById(personRecordId).orElse(null);
 if (personRecord == null)
 return;
 for (Long documentId : associationDTO.getDocumentsId())
 documentRepository
 .findById(documentId)
 .ifPresent(document -> personRecord.getDocuments().remove(document));
 personRecordRepository.save(personRecord);
 }

One method is for adding relations, the other is to remove them.

I definitely get the smell of duplicated code and the only thing that changes is remove or add between the two methods. How could I refactor this code in the most elegant way?

Answer 1

You may extract the action part as a method parameter (I am using BiConsumer in this case).

@Override
public void performActionOnRecords(Long personRecordId, AssociationDTO associationDTO, BiConsumer<PersonRecord,Document> action) {
 PersonRecord personRecord = personRecordRepository.findById(personRecordId).orElse(null);
 if (personRecord == null)
 return;
 for (Long documentId : associationDTO.getDocumentsId())
 documentRepository
 .findById(documentId)
 .ifPresent(document -> action.accept(personRecord,document));
 personRecordRepository.save(personRecord);
}

and call the methods as

performActionOnRecords(personId, associationDTO, (personRecord, document) -> personRecord.getDocuments().add(document)); // To add document

and,

performActionOnRecords(personId, associationDTO, (personRecord, document) -> personRecord.getDocuments().remove(document)); // To remove document