1. Hibernate Foreign Key Name Generator Download

Posted by: carcophan
Date: January 20, 2006 03:06AM

Hibernate Foreign Key Name Generator Download

If you use a List, or other indexed collection, set the key column of the foreign key to not null. Hibernate will manage the association from the collections side to maintain the index of each element, making the other side virtually inverse by setting update='false' and insert='false'.

  1. To govern this process Hibernate ™ uses a reverse engineering strategy. A reverse engineering strategy is mainly called to provide more Java like names for tables, column and foreign keys into classes, properties and associations. It is also used to provide mappings from SQL types to Hibernate ™ types. The strategy can be customized by the.
  2. Generator classes in hibernate are used to generate the primary key ids, the types we have sequence, identity, increment, hilo, native and foreign and uuid generators. Here we discussed hilo generator formula in detaild explanation. Hibernate generator classes have been used to generating the primary key.
  3. Jun 11, 2015 Hibernate provides a tool to automatically generate the database schema from the mapping files. The generated schema includes ‘create table’, ‘alter table’, referential integrity constraints, primary and foreign keys. Create some POJO persistent classes. Create mapping files. Configure the Dialect. Customize your mapping files to improve the generated schema. Run SchemaExport tool to.
  4. Changing the generated name of a foreign key in Hibernate. Keys usually just result in the name of the foreign key being spit out by the database, naming the keys.

Hi,
I'm posting a Hibernate problem here because nobody could help me solve my problem at forum.hibernate.org. I've tried google, and the Hibernate manual too, and I've tried all sorts of workarounds , without any luck! - So I was hoping, someone here could give me some advice. Anyway here's the reason for my post:
(Using Hibernate 3.1 and MySQL 4.1.14 on SuSE 9.2)
I've got 2 Tables: Parent and Child:
CREATE TABLE `parent` (
`id` int(11) NOT NULL auto_increment,
`name` varchar(20) default NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
CREATE TABLE `child` (
`id` int(11) NOT NULL auto_increment,
`name` varchar(30) default NULL,
`parent_id` int(11) NOT NULL default '0',
PRIMARY KEY (`id`),
KEY `parent_id` (`parent_id`),
CONSTRAINT `child_ibfk_1` FOREIGN KEY (`parent_id`) REFERENCES `parent` (`id`) ON DELETE CASCADE ON UPDATE CASCADE
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
Here are my Mapping Files for:
Parent:
<hibernate-mapping>
<class name='entities.Parent' table='parent' >
<id name='id' column='id' unsaved-value='-1' type='long'>
<generator/>
</id>
<property name='name' />
<set name='children' inverse='true' cascade='all'>
<key column='parent_id' not-null='true' />
<one-to-many />
</set>
</class>
</hibernate-mapping>
and Child:
<hibernate-mapping>
<class name='entities.Child' table='child'>
<id name='id' column='id' unsaved-value='-1' type='long'>
<generator/>
</id>
<property name='name' />
<property name='parent_id' not-null='true' />
</class>
</hibernate-mapping>
When I load a Parent all works fine, and hibernate populates all the Child Objects associated with the Parent, and adds them to the HashSet.
But when I try to create a new Parent and add new Children to the Parent, I get the following error:
org.hibernate.exception.ConstraintViolationException: could not insert: [entities.Child]
and...
Caused by: java.sql.SQLException: Cannot add or update a child row: a foreign key constraint fails
Here's my Java Code for the parent and child classes:
package entities;
public class Child {
private String name = null;
private long id = -1;
private long parent_id= -1;
public long getParent_id() {
return parent_id;
}
public void setParent_id(long parent_id) {
this.parent_id = parent_id;
}
public long getId() {
return id;
}
public void setId(long id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
package entities;
import java.util.Set;
public class Parent {
private String name = null;
private long id = -1;
private Set children = null;
public Set getChildren() {
return children;
}
public void setChildren(Set children) {
this.children = children;
}
public long getId() {
return id;
}
public void setId(long id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
this is what I do when I try to create and save a new Parent with new Children:
Session session = SessionManager.getSessionFactory().getCurrentSession();
session.beginTransaction();
Parent p= new Parent();
p.setName('mom');
Child c = new Child();
c.setName('kid1');
p.setChildren(new HashSet());
p.getChildren().add(c);
session.save(p);
session.getTransaction().commit();
Apparently to me, Hibernate doesn't know the Parents id at the time of saving and therefore cant set the foreign key of the Parent_id in the Child table. But how to I tell Hibernate that it should update this foreign key?
This problem has been haunting me for days now, and I cant solve it on my own. Maybe someones got some helpful hints on how to solve this problem.

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