Duplicate entry error occurs on saveorupdate method

Question

I tried to do use saveorupdate method in hibernate and it resulted in

com.mysql.jdbc.exceptions.jdbc4.MySQLIntegrityConstraintViolationException: Duplicate entry 'Mobiles' for key 'type_name'

This is my code

public ItemType addItemType(String typeName) {
    Session session = factory.openSession();

    Transaction tx = null;
    ItemType itemType = null;
    try{
        tx = session.beginTransaction();
        itemType = new ItemType();
        itemType.setTypeName(typeName);
        itemType.setDescription("");
        itemType.setCreatedBy("shoppingcart");
        itemType.setCreatedDate(new Date());
        itemType.setUpdatedBy("shoppingcart");
        itemType.setUpdatedDate(new Date());
        session.saveOrUpdate(itemType); 
        tx.commit();
    }catch (HibernateException e) {
        if (tx!=null) tx.rollback();
        e.printStackTrace(); 
    }finally {
        session.close(); 
    }
    return itemType;
}

and this is the ItemType class

@Entity
@Table(name = "item_types")
public class ItemType implements Serializable{

/**
 * 
 */
private static final long serialVersionUID = 1L;

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "item_type_id")
private String typeId;

@Column(name = "type_name")
private String typeName;

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

@Column(name = "created_date")
private Date createdDate;
@Column(name = "created_user")
private String createdBy;
@Column(name = "updated_date")
private Date updatedDate;
@Column(name = "updated_user")
private String updatedBy;

public String getTypeName() {
    return typeName;
}

public void setTypeName(String typeName) {
    this.typeName = typeName;
}

public String getDescription() {
    return description;
}

public void setDescription(String description) {
    this.description = description;
}

public String getTypeId() {
    return typeId;
}

public void setTypeId(String typeId) {
    this.typeId = typeId;
}

public Date getCreatedDate() {
    return createdDate;
}

public void setCreatedDate(Date createdDate) {
    this.createdDate = createdDate;
}

public String getCreatedBy() {
    return createdBy;
}

public void setCreatedBy(String createdBy) {
    this.createdBy = createdBy;
}

public Date getUpdatedDate() {
    return updatedDate;
}

public void setUpdatedDate(Date updatedDate) {
    this.updatedDate = updatedDate;
}

public String getUpdatedBy() {
    return updatedBy;
}

public void setUpdatedBy(String updatedBy) {
    this.updatedBy = updatedBy;
}   


}

First I made an insert entry and it is working fine and when I try to update, I guess it tries to make an insert and results in the above error. Please help.

UPDATE

This is the table structure in db

DROP TABLE IF EXISTS `shopping_cart`.`item_types`;
CREATE TABLE  `shopping_cart`.`item_types` (
`item_type_id` int(10) unsigned NOT NULL AUTO_INCREMENT,
`type_name` varchar(45) NOT NULL,
`description` varchar(450) DEFAULT NULL,
`created_user` varchar(45) NOT NULL,
`created_date` datetime NOT NULL,
`updated_user` varchar(45) NOT NULL,
`updated_date` datetime NOT NULL,
PRIMARY KEY (`item_type_id`),
UNIQUE KEY `type_name` (`type_name`)
) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=latin1;

Answer 1

Your code always saves a new ItemType, and because your database my have an unique constraint on "type_name" you get that exception the second time your try to run this method (for the same type_name).

So, you can't be using hbmddl, because otherwise your Hibernate ItemType model must have used:

@Column(name = "type_name", unique = "true")
private String typeName;

You need to select the ItemType by typeName before doing a save:

public ItemType addItemType(String typeName) {
    Session session = factory.openSession();

    Transaction tx = null;
    ItemType itemType = null;
    try{
        tx = session.beginTransaction();
        itemType = session.createQuery("select it from ItemType where typeName = :typeName")
                   .setParameter("typeName", typeName)
                   .uniqueResult();
        if(itemType == null) {
            itemType = new ItemType();
            itemType.setTypeName(typeName);
            itemType.setDescription("");
            itemType.setCreatedBy("shoppingcart")    
            itemType.setCreatedDate(new Date());
        }
        itemType.setUpdatedBy("shoppingcart");
        itemType.setUpdatedDate(new Date());
        session.saveOrUpdate(itemType); 
        tx.commit();
    }catch (HibernateException e) {
        if (tx!=null) tx.rollback();
            e.printStackTrace(); 
    }finally {
        session.close(); 
    }
    return itemType;
}

Answer 2

If you're just running the same code, trying to update entity instead of saving it, it'll gonna fail. To update an entity with this method, you must not create a new ItemType, but get it from db, using session.get(ItemType.class, id); - that way hibernate will understand, that this entity is already in db, and try to update it, not to save a new one