PersistentManager and Transaction

PersistentManager is used to manage database connection, state of the persistent objects and transaction when the application is running. A database transaction is a unit of the application. It is used to keep integrity of your data in database. Our Persistent Library provides a transaction API for you to create, commit and rollback the transaction for your application.

Start Transaction

When you need to start a transaction, you need to get the session from the PersistentManager and call the beginTransaction function (PersistentManager.instance().getSession().beginTransaction();). Here is a sample:

PersistentTransaction t = PersistentManager.instance().getSession().beginTransaction();

Commit Transaction

After you have inserted/updated/deleted data, you can call the commit function of the transaction object to commit your changes to Database.

t.commit();

Rollback Transaction

In case there are any exception, you can call the rollback function to cancel all the operation.

t.rollback();

Sample Code

The following is an example of using the transaction API.

private Course fireOK() throws PersistentException {
   PersistentTransaction t = SchoolSystemPersistentManager.instance().getSession().beginTransaction();
   try {Course lCourse = CourseFactory.createCourse();
      lCourse.setTitle(getTitleTextField().getText());
      lCourse.setDescription(getDescriptionTextField().getText());
      lCourse.setTeacher(_teacher);
      _teacher.save();
      t.commit();
      return lCourse;
   } catch (Exception e) {
      e.printStackTrace();
      t.rollback();
   }
   return null;
}