无法解析方法，使用 JPA 数据的 Spring Boot 应用程序

Question

I would like to store a method in a helper class and call that method from another class. The method also fetches data from a jpa repository.

For some reason when i call the method from the helper class, i get an error : Cannot resolve method 'getDocumentListByProduit' in 'DocumentHelper'. The method name doesn't show in IDE's autocompletion either. It's like the method isn't mapped for some reason. Any hints why? thanks in advance.

class from where i wish to call the method:

@Entity
@Table(name = "document", schema = "table_name")
public class Document {
   private int id;
   private String url;
   private String type;
   private String titre;
   private String description;

   @Autowired
   private DocumentHelper dh;

...

  public Map<String, List<Document>> getDocumentListByProduit(int id){
       Map<String, List<Document>> ret = dh.getDocumentListByProduit(id);
       return ret;
   }

the helper class :

@Component
public class DocumentHelper {

   @Autowired
   private DocumentRepository dr;

   public DocumentHelper() {
   }


   public Map<String, List<Document>> getDocumentListByProduit(int id) {
       Map<String, List<Document>> ret = new HashMap<>();
       List<Document> listImg = new ArrayList<>();
       List<Document> listOther = new ArrayList<>();
       List<Document> dList = new ArrayList<>();
       try {
           dList = dr.getDocumentListByProduit(id);
           for (Document tDoc : dList) {
               if (tDoc.getType().equals("image")) {
                   listImg.add(tDoc);
               } else {
                   listOther.add(tDoc);
               }
           }
           ret.put("imageCollection", listImg);
           ret.put("otherCollection", listOther);
       } catch (Exception e) {
           throw new DAOException("Une erreur est survenue : " + e.getMessage());
       }
       return ret;
   }
}

then the Repository:

public interface DocumentRepository extends JpaRepository<Document, Integer> {

    // in method getDocumentListByProduit in DocumentHelper
    @Query(value = "SELECT * FROM DOCUMENT D, DOCUMENT_PRODUIT DP WHERE D.id = DP.id_document AND DP.id_produit = :id_produit;", nativeQuery = true)
    List<Document> getDocumentListByProduit(@Param("id_produit") int id_produit);

}

Answer 1

JPA doesn't use the Spring container to instantiate its entities, so Spring does not inject dependencies into entities by default.

You can inject dependencies into objects not managed by the Spring container using @Configurable as described here . This approach requires configuring AspectJ into the project.

Another way would be injecting dependencies manually after JPA constructed an entity using AutowireCapableBeanFactory#autowireBean . This approach may be considered as a bad practice because of repetitiveness if you need it more than in one case.