ch.codebulb.crudlet.service

Class CrudService<T extends CrudIdentifiable>

java.lang.Object

ch.codebulb.crudlet.service.CrudService<T>

All Implemented Interfaces:

Serializable

Direct Known Subclasses:

CrudServiceMocked

public abstract class CrudService<T extends CrudIdentifiable>
extends Object
implements Serializable

An abstract generic base implementation of a CRUD persistence storage access "service" (a "persistence service"), making it easy to derive a best-practices compliant concrete CRUD service implementation.

This service realizes the basic CRUD operations:

• Create (C): create() + save()
• Read (R): findById(Long id) / findAll()
• Update (U): save()
• Delete (D): delete()

In order to create a CRUD service for an entity type, make sure the entity implements CrudIdentifiable (or inherits from CrudEntity), implement CrudService for the entity and register it as a CDI bean in the container (depending on beans.xml bean-discovery-mode, explicit registration may not be necessary).

As an example, a service implementation for a Customer entity can extend CrudService like this:

public class CustomerService extends CrudService<Customer> {
    @Override
    @PersistenceContext
    protected void setEm(EntityManager em) {
        super.setEm(em);
    }

    @Override
    public Customer create() {
        return new Customer();
    }

    @Override
    public Class<Customer> getModelClass() {
        return Customer.class;
    }
}
                

• Within the setEm(EntityManager) method, simply call the super method. The important part is that you inject your @PersistenceContext in this method by annotation.

You can immediately use this service in a backing bean with full support for CRUD operations on your persistence storage.

Conveniently, Crudlet also comes with an alternative implementation of CrudService named CrudServiceMocked. As its name suggests, this implementation's "persistence" functionality is based on a simple HashMap storing the saved entities. Whilst of no use in a real-world production environment, this class might come in handy if you want to try something out without having a proper database / persistence configuration set up. You may then use a CrudServiceMocked implementation as e.g. a @SessionScoped bean, and later change to a true CrudService without any interface changes.

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected javax.persistence.EntityManager	em

Constructor Summary

Constructors

Constructor and Description
CrudService()

Method Summary

Modifier and Type	Method and Description
long	countAll() Counts the number of entities.
abstract T	create() Invokes the constructor for the entity type.
void	delete(Long id) Deletes the entity with the CrudEntity.getId() provided.
List<T>	findAll() Returns a List of all entities.
T	findById(Long id) Returns the entity with the CrudEntity.getId() provided.
abstract Class<T>	getModelClass() Returns the entity type.
T	save(T entity) Saves / Inserts / Updates the entity provided and returns the updated entity (e.g. updated CrudEntity.getId() field.
protected void	setEm(javax.persistence.EntityManager em) Sets the entity manager.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

em

protected javax.persistence.EntityManager em

Constructor Detail

CrudService

public CrudService()

Method Detail

create

public abstract T create()

Invokes the constructor for the entity type.

getModelClass

public abstract Class<T> getModelClass()

Returns the entity type.

setEm

protected void setEm(javax.persistence.EntityManager em)

Sets the entity manager. Override this method to dependency-inject an EntityManager with the associated @PersistenceContext

findById

public T findById(Long id)

Returns the entity with the CrudEntity.getId() provided.

findAll

public List<T> findAll()

Returns a List of all entities.

countAll

public long countAll()

Counts the number of entities.

save

public T save(@NotNull
              T entity)

Saves / Inserts / Updates the entity provided and returns the updated entity (e.g. updated CrudEntity.getId() field.

Note: It's important to continue to work with the newly returned, updated entity rather than with the original entity.

delete

public void delete(Long id)

Deletes the entity with the CrudEntity.getId() provided.