persist « Key « JPA Q&A

1. Handling creation of ORM objects prior to persistence/generation of primary keys?

Bear with me as I try to simplify my issue as much as possible. I am creating a new ORM object. This object has an auto generated primary key which is created ...

2. JPA: Weird error when I try to persist an object

I got a OneToMany relation between User and Group

public class Group {

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

private String groupid;

private User user;
public class User {

@GeneratedValue(strategy ...

3. Foreign key problem in Java Persistance API with Netbeans 6.9.1

I have an error in setting up Java Persistence in Netbeans. I have used MySQL as Back-End Database Server. My Code is as below, Database

 `hub_ID` INT(11) NOT NULL ...

4. JPA Key generation in the class of the many side

I am new to JPA. I want to comprehed what kind of assistence gives me JPA in persisting objects to database. My example: a Person class is related to an Address class. ...

5. Beginner Question - Assign Key without Persisting

In my current project, I create new objects, and the process of creating them compares them to a list of previous objects (based on object key). However, I do not have the time to check every item in the database when I create new objects in order to assign a unique key, and I need to create several objects (including several ...

6. problems persisting primary/foreign keys in 1-N objects/rela

Newbie Joined: Tue Jun 22, 2010 2:26 am Posts: 4 i have two objects, Company and Employee. the relationship between these two objects are one to many (1-N); one Company has many Employees. when i instantiate a Company with a List of Employees, i cannot get the to persist to the Employee.companyId table/field. can someone tell me what i am ...

7. key type independent persistent objects

we want to hav our pojos independent from the generated db-keys. as string if possible public class Teehaus { private String key = null; } not any code should change when the tables move from integer to bigint or uuid. the mapping file may change. do we have to implement custom types which do the conversion for us like StringToInt, StringToBigInt ...

8. Persistence by reachability causes primary key un-populated

I'm using Spring + Hibernate. I'm writing a test for Blog and BlogEntry class. A Blog has a List of BlogEntry object. The mapping of the classes are shown below. Blog blog = new Blog(); getHibernateTemplate().saveOrUpdate(blog); // persisted the blog... verified it by checking the Blog table... ID=12 BlogEntry blogEntry = new BlogEntry(); blog.addBlogEntry(blogEntry); getHibernateTemplate().saveOrUpdate(blog); // persisted the blogEntry... verified by ...

9. Only Primary key being persisted