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javapostgresqlspring-mvclazy-initialization

Problem with LazyInitializationException and Correct setting ManyToOne

I have 3 object that interfacing each other like that:

@Entity
public class Room {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;

    @Column
    private String name;

    @OneToMany(mappedBy = "room", fetch = FetchType.EAGER)
    private List<SponsorStart> sponsorsStart = new ArrayList<>();

    @OneToMany(mappedBy = "room", fetch = FetchType.LAZY)
    private List<SponsorFinish> sponsorsFinish = new ArrayList<>();
    //getters and setters
    ```
@Entity
public class SponsorStart {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;

    @ManyToOne(cascade = CascadeType.ALL)
    @JoinColumn(name = "room_id")
    private Room room;

    @OneToMany(cascade = CascadeType.ALL)
    private List<Post> posts;
//getters and setters

@Entity
public class Post {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;
    @Column
    private long pk;
    @Column
    private String postId;
    //getters and setters

if set settings like top then results here: enter image description here Note that displayed 4 rows (3 if start from 0) But if i want to get list of post form SponsorStart object i get:

org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: com.spring.givestracker.model.SponsorStart.posts, could not initialize proxy - no Session
        at org.hibernate.collection.internal.AbstractPersistentCollection.throwLazyInitializationException(AbstractPersistentCollection.java:597)
        at org.hibernate.collection.internal.AbstractPersistentCollection.withTemporarySessionIfNeeded(AbstractPersistentCollection.java:216)
        at org.hibernate.collection.internal.AbstractPersistentCollection.initialize(AbstractPersistentCollection.java:576)
        at org.hibernate.collection.internal.AbstractPersistentCollection.read(AbstractPersistentCollection.java:147)
        at org.hibernate.collection.internal.PersistentBag.iterator(PersistentBag.java:303)
        at com.spring.givestracker.service.impl.SponsorsFinishServiceImpl.parseSponsorFinishByRoom(SponsorsFinishServiceImpl.java:78)
Here is lazy:
    for (SponsorStart sponsorStart : room.getSponsorsStart()) {
            Hibernate.initialize(sponsorStart.getPosts());
         }

Okay, i thought i know problem and in SponsorStart Entity added:

    @OneToMany(cascade = CascadeType.ALL, fetch = FetchType.EAGER)
    private List<Post> posts;

But! I have this problem! enter image description here Yes here is problem! I have total 43 post in 4 SonsorStart entity, why it displayed like that and what should i do to fix it?

Help)

UPDATE 1

@Entity
public class Room {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;

    @Column
    private String name;

    @OneToMany(mappedBy = "room", fetch = FetchType.EAGER, cascade = CascadeType.ALL)
    private List<SponsorStart> sponsorsStart = new ArrayList<>();

    @OneToMany(mappedBy = "room", fetch = FetchType.LAZY, cascade = CascadeType.ALL)
    private List<SponsorFinish> sponsorsFinish = new ArrayList<>();
    //getters and setters

@Entity
public class SponsorStart {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;

    @ManyToOne (fetch=FetchType.LAZY,
            cascade=CascadeType.ALL)
    @JoinColumn(name = "room_id")
    private Room room;

     @OneToMany(mappedBy = "sponsorStart", cascade = CascadeType.ALL)
    private List<Post> posts;
//getters and setters

@Entity
public class Post {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;
    @Column
    private long pk;
    @Column
    private String postId;
    @ManyToOne(fetch=FetchType.LAZY)
    private SponsorStart sponsorStart;

 //getters and setters

And i faced with lazy initialization

org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: com.spring.givestracker.model.SponsorStart.posts, could not initialize proxy - no Session
        at org.hibernate.collection.internal.AbstractPersistentCollection.throwLazyInitializationException(AbstractPersistentCollection.java:597)
        at org.hibernate.collection.internal.AbstractPersistentCollection.withTemporarySessionIfNeeded(AbstractPersistentCollection.java:216)
        at org.hibernate.collection.internal.AbstractPersistentCollection.initialize(AbstractPersistentCollection.java:576)
        at org.hibernate.collection.internal.AbstractPersistentCollection.forceInitialization(AbstractPersistentCollection.java:744)
        at org.hibernate.Hibernate.initialize(Hibernate.java:64)
        at com.spring.givestracker.service.impl.SponsorsFinishServiceImpl.parseSponsorFinishByRoom(SponsorsFinishServiceImpl.java:73)
Solution

  • From RoomController using RoomService i get findRoomById(id), RoomService has @Transactional, and from RoomController i gave the Room was found to another service. When i delegated another service used RoomService to findRoomById(id) the problem with Lazy the problem disappeared! But i dont know what was that when i have 4 sponsors but hibernate load me 43 times 4 sponsors) because sponsors get 43 posts...