@Basic(fetch = FetchType.LAZY) does not work?

Question

I use JPA (Hibernate) with Spring. When i want to lazy load a Stirng property i use this syntax:

@Lob
@Basic(fetch = FetchType.LAZY)
public String getHtmlSum         


        

Answer 1

@Entity
public class User implements FieldHandled {

    @Id
    private String uid;

    private String uname;

    private int age;

    @Lob
    @Basic(fetch = FetchType.LAZY)
    private byte[] img;

    private FieldHandler fieldHandler;

    public User() {
    }

    // getter() and setter() of uid, uname, age

    public byte[] getImg() {
        // if User user = new User() then fieldHandler is null
        // if User user = entityManager.find(User.class, "001") then fieldHandler is not null
       if(img != null) { 
           return img;
       }

       if (fieldHandler != null) { 
           return (byte[]) fieldHandler.readObject(this, "img", img);
       } else {
           return null;
       }  
    }

    public void setImg(byte[] img) {
        this.img = img;
    }

    public void setFieldHandler(FieldHandler fieldHandler) {
        this.fieldHandler = fieldHandler;
    }

    public FieldHandler getFieldHandler() {
        return fieldHandler;
    }
}

I use Hibernate4 h2database.I am sure lazy loading can work fine by my code.

Hibernate: select user0_.uid as uid1_0_0_, user0_.age as age2_0_0_, user0_.uname as uname4_0_0_ from User user0_ where user0_.uid=?

Hibernate: select user_.img as img3_0_ from User user_ where user_.uid=?

if use repository.save(User) to add a new User will be ok, but update a User will throw a exception

java.lang.ClassCastException: org.hibernate.bytecode.instrumentation.spi.LazyPropertyInitializer$1 cannot be cast to java.sql.Blob

I suggest use repository.delete(userid) before repository.save in one transactional, then it will work fine.