com.devonfw.module.jpa.dataaccess.api

Class JpaHelper

java.lang.Object

com.devonfw.module.jpa.dataaccess.api.JpaHelper

public class JpaHelper
extends Object

Helper class for generic handling of persistence entities (based on EntityManager). In some cases it is required to access JPA features in a static way. E.g. a common case is a setter in your entity for a reference from an ETO that can be achieved via the following code:

 @Entity
 @Table("Foo")
 public class FooEntity extends ApplicationPersistenceEntity implements Foo {
   @OneToOne(fetch = FetchType.LAZY, cascade = CascadeType.ALL)
   @JoinColumn(name = "bar")
   private BarEntity bar;
   ...
   @Override
   public void setBarId(IdRef <Bar> barId) {
     this.bar = JpaHelper.asEntity(barId, BarEntity.class);
   }
 }
 

Since:

3.0.0

Constructor Summary

Constructors

Constructor and Description
JpaHelper()

Method Summary

Modifier and Type	Method and Description
static <E extends GenericEntity<?>,P extends E> void	asEntities(Collection<? extends E> input, Class<P> entityClass, Collection<P> output)
static <E> E	asEntity(Ref<?,? super E> reference, Class<E> entityClass)

Methods inherited from class java.lang.Object

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

Constructor Detail

JpaHelper

public JpaHelper()

Method Detail

asEntity

public static <E> E asEntity(Ref<?,? super E> reference,
                             Class<E> entityClass)

Type Parameters:

E - generic type of the entity.

Parameters:

reference - the Ref or null. Typically an IdRef.

entityClass - the entity Class.

Returns:

the entity of the specified Class with the ID from the given GenericIdRef or null if the given Ref is null.

asEntities

public static <E extends GenericEntity<?>,P extends E> void asEntities(Collection<? extends E> input,
                                                                       Class<P> entityClass,
                                                                       Collection<P> output)

Type Parameters:

E - generic type of the input entities (most commonly the entity interface).

P - generic type of the output entities.

Parameters:

input - the Collection of entities (e.g. ETOs) to use as input.

entityClass - the Class reflecting the entity.

output - die Collection where to add the entities corresponding to the input entities. Most probably empty but may also already contain entities so this method will add additional entities.