JPA @ManyToMany问题通过C表从A到B（不是双向），但是不是通过主键连接到B

Question

I have an JPA @ManyToMany issue

I have One Main entity called Report . I have several entities connect to Report with ManyToMany Relation. The connection is done via extra table. ie with @JoinTable annotation. Each relation is lazy .

I have a function that fetch the report with all its relations. now, if i do fetch by accessing the property (ie mark the function as @Transcational and access to each one of the property) everything works as expected. But , if I do

 CriteriaBuilder cb = em.getCriteriaBuilder();
 CriteriaQuery<Report> query = cb.createQuery(Report.class);
 Root<Report> report = query.from(Report.class);

 ArrayList<Predicate> preds = new ArrayList<Predicate>();
 DomainSpecification.<Report>eager().toPredicate(report, query, cb);
 preds.add(DomainSpecification.<Report>idIsEqual(id).toPredicate(report, query, cb));
 query.where(cb.and(preds.toArray(new Predicate[preds.size()])));

 query.select(report);
 List<Report> results = em.createQuery(query).setMaxResults(1).get

I get all the relations as well but One of the relation (that has been connected to another table NOT by primary key) is fetching alots times. This means that the length of r.getProjects() is 13823 of the same value. ie of the same Project.

I'm attaching here the relevant source from Domain Specification / Report.java / Project.java and Keyword.java (the keyword is just to show an example for an entity that works good with this kind of fetching) Maybe one can throw some light on this issues.

Thanks, Oak

Additional Information

Code

Report.java

@Entity(name = "reports") public class Report implements Serializable, Auditing,JppDbObject {

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "REPORT_ID", unique = true, nullable = false)
private Long id;

@JsonIgnore
@OneToOne(cascade = CascadeType.ALL, mappedBy = "report")
private ReportId report;
/*
 * this here for updating the reports_ids table.
 * 
 * set json ignore over this field.
 */

@Column(name = "txt", nullable = false)
private String txt;

@Column(name = "cleanTxt")
private String cleanTxt;

@CreatedDate
@Column(name = "CREATION_DATE", nullable = false)
private Date creationDate;

@LastModifiedDate
@Column(name = "LAST_MODIFIED", nullable = false)
private Date lastModified;

@Column(name = "status", nullable = false)
private Integer status;

@CreatedBy
@JsonIgnore
@ManyToOne(optional = true)
@JoinColumn(name="CREATOR_ID", referencedColumnName = "ID")
private User createdBy;

@LastModifiedBy
@ManyToOne(optional = true)
@JoinColumn(name="MODIFIER_ID", referencedColumnName = "ID")
private User modifiedBy;

@JsonIgnore
@OneToMany(mappedBy="reportCommented")
//TODO make sure comments works good with lazy. @OneToMany(fetch=FetchType.EAGER, mappedBy="reportCommented")
private Set<ReportComment> comments;

/* this is the important line*/
@JsonIgnore
@ManyToMany
@JoinTable(
      name="reports_projects",
      joinColumns={@JoinColumn(name="report_id", referencedColumnName="REPORT_ID")},
      inverseJoinColumns={@JoinColumn(name="project", referencedColumnName="CODE")})
private List<Project> projects;

@JsonIgnore
@ManyToMany
@JoinTable(
        name="reports_keywords",
        joinColumns={@JoinColumn(name="report_id", referencedColumnName="REPORT_ID")},
        inverseJoinColumns={@JoinColumn(name="keyword_id", referencedColumnName="keyword_id")})
private Set<Keyword> keywords;

Project.java

@Entity(name = "projects") public class Project implements Serializable{

@Id
@GeneratedValue(strategy = GenerationType.AUTO)
@Column(name = "PROJECT_ID")
private long id;

@Column(name = "CODE", nullable = false,unique = true)
private String code;

@Column(name = "DESCRIPTION", nullable = false)
private String description;

@CreatedDate
@Column(name = "CREATION_DATE", nullable = false)
private Date creationDate;

@JsonIgnore
@OneToMany(mappedBy = "id.proj", cascade = {CascadeType.ALL}, orphanRemoval=true)
private List<ProjectPermission> permissions;

Domain Specification

public class DomainSpecification {

public static <T> Specification<T> eager() {

    return new Specification<T>() {

        @Override
        public Predicate toPredicate(Root<T> root, CriteriaQuery<?> query, CriteriaBuilder cb) {
            for (PluralAttribute<? super T, ?, ?> fetch : root.getModel().getPluralAttributes()) {
                root.fetch(fetch, JoinType.LEFT);
            }
            query.distinct(true);
            return null;
        }

    };
}

public static <T> Specification<T> idIsEqual(final Long id) {

    return new Specification<T>() {

        @Override
        public Predicate toPredicate(Root<T> root, CriteriaQuery<?> query, CriteriaBuilder cb) {

                        return cb.equal(root.get("id"),id);

        }

    };
}

}

System

• Spring (4.0.6.RELEASE)
• Spring-Data (1.6.2.RELEASE)
• Hibernate EntityManager (4.3.6.Final - 4.2.1)
• MySQl Connector (5.1.13)
• cglib (3.1)
• aspectj (1.8.1)

Answer 1

Seems that the issue was connecting two table not via primary key. Although this can be done via normal sql. JPA produces unexpected result for me.