Book Image

Seam 2.x Web Development

Book Image

Seam 2.x Web Development

Overview of this book

The Seam framework from JBoss allows developers to use JSF, Facelets, EJB, and JPA to write conversational web applications. But you will first have to learn how these standard technologies are integrated using Seam and how they can be built upon using additional Seam components. If you need to build a Java web application fast, but don't have time to learn all these complex features, then this book is for you. The book provides a practical approach to developing Seam applications highlighting good development practices. It provides a complete walk through to develop Web applications using Seam, Facelets, and RichFaces and explains how to deploy them to the JBoss Application Server. You can start using key aspects of the Seam framework immediately because this book builds on them chapter by chapter, finally ending with details of enterprise functionality such as PDF report generation and event frameworks. First, the book introduces you to the fundamentals of Seam applications, describing topics such as Injection, Outjection and Bijection. You will understand the Facelets framework, AJAX, database persistence, and advanced Seam concepts through the many examples in the book. The book takes a practical approach throughout to describing the technologies and tools involved. You will add functionality to Seam applications after you learn how to use the Seam Generator RAD tools and how to customize and fully test application functionality. Hints and tips are provided along the way of how to use Seam and the JBoss Application Server.
Table of Contents (17 chapters)
Seam 2.x Web Development
Credits
About the author
About the reviewers
Preface

Performing CRUD operations on entities


In addition to persisting and retrieving entities from the database, JPA also allows us to delete and update data from the database. Deleting is achieved using the remove() method on the entity manager.

If we already have an instance on an entity that we wish to delete, we can simply call the remove() method to delete it.

@PersistenceContext
EntityManager em
…
em.remove(customer);

If we do not have an instance of an entity to remove, we can first find and load it from the database using the find() method of the entity manager.

Customer customer = em.find(Customer.class, customerId);
em.remove(customer);

To update an entity in the database, we simply get an instance of the object and invoke the relevant setters on it. As the code that is running is inside a Session Bean method using Container Managed Persistence, any changes to the object will be persisted to the database when the method exits. Once again, we can use the find() method of the entity manager...