HHH-11186 - Add example for all Hibernate annotations
Document more annotations: - @NotFound
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@ -1006,6 +1006,8 @@ The `NotFoundAction` defines with two possibilities:
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`EXCEPTION`:: An exception is thrown when an element is not found (default and recommended).
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`IGNORE`:: Ignore the element when not found in the database.
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See the <<chapters/domain/associations.adoc#associations-not-found,`@NotFound` mapping>> section for more info.
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[[annotations-hibernate-ondelete]]
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==== `@OnDelete`
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@ -388,3 +388,69 @@ include::{extrasdir}/associations-many-to-many-bidirectional-with-link-entity-li
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====
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There is only one delete statement executed because, this time, the association is controlled by the `@ManyToOne` side which only has to monitor the state of the underlying foreign key relationship to trigger the right DML statement.
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[[associations-not-found]]
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==== `@NotFound` association mapping
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When dealing with associations which are not enforced by a Foreign Key,
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it's possible to bump into inconsistencies if the child record cannot reference a parent entity.
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By default, Hibernate will complain whenever a child association references a non-existing parent record.
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However, you can configure this behavior so that Hibernate can ignore such an Exception and simply assign `null` as a parent object referenced.
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To ignore non-existing parent entity references, even though not really recommended, it's possible to use the annotation `org.hibernate.annotation.NotFound` annotation with a value of `org.hibernate.annotations.NotFoundAction.IGNORE`.
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Considering the following `City` and `Person` entity mappings:
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[[associations-not-found-domain-model-example]]
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.`@NotFound` mapping example
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====
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[source,java]
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----
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include::{sourcedir}/NotFoundTest.java[tags=associations-not-found-domain-model-example,indent=0]
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----
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====
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If we have the following entities in our database:
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[[associations-not-found-persist-example]]
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.`@NotFound` mapping example
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====
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[source,java]
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----
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include::{sourcedir}/NotFoundTest.java[tags=associations-not-found-persist-example,indent=0]
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----
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====
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When loading the `Person` entity, Hibernate is able to locate the associated `City` parent entity:
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[[associations-not-found-find-example]]
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.`@NotFound` find existing entity example
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====
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[source,java]
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----
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include::{sourcedir}/NotFoundTest.java[tags=associations-not-found-find-example,indent=0]
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----
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====
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However, if we change the `cityName` attribute to a non-existing city:
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[[associations-not-found-non-existing-persist-example]]
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.`@NotFound` change to non-existing City example
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====
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[source,java]
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----
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include::{sourcedir}/NotFoundTest.java[tags=associations-not-found-non-existing-persist-example,indent=0]
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----
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====
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Hibernate is not going to throw any exception, and it will assign a value of `null` for the non-existing `City` entity reference:
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[[associations-not-found-non-existing-find-example]]
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.`@NotFound` find non-existing City example
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====
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[source,java]
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----
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include::{sourcedir}/NotFoundTest.java[tags=associations-not-found-non-existing-find-example,indent=0]
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----
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====
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@ -0,0 +1,162 @@
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package org.hibernate.userguide.associations;
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import java.io.Serializable;
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import javax.persistence.Entity;
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import javax.persistence.FetchType;
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import javax.persistence.GeneratedValue;
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import javax.persistence.Id;
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import javax.persistence.JoinColumn;
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import javax.persistence.ManyToOne;
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import javax.persistence.Table;
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import org.hibernate.annotations.NotFound;
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import org.hibernate.annotations.NotFoundAction;
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import org.hibernate.jpa.test.BaseEntityManagerFunctionalTestCase;
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import org.junit.Test;
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import static org.hibernate.testing.transaction.TransactionUtil.doInJPA;
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import static org.junit.Assert.assertEquals;
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import static org.junit.Assert.assertNull;
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/**
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* @author Fábio Ueno
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*/
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public class NotFoundTest extends BaseEntityManagerFunctionalTestCase {
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@Override
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protected Class<?>[] getAnnotatedClasses() {
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return new Class<?>[] {
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Person.class,
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City.class
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};
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}
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@Test
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public void test() {
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doInJPA( this::entityManagerFactory, entityManager -> {
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//tag::associations-not-found-persist-example[]
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City _NewYork = new City();
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_NewYork.setName( "New York" );
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entityManager.persist( _NewYork );
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Person person = new Person();
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person.setId( 1L );
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person.setName( "John Doe" );
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person.setCityName( "New York" );
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entityManager.persist( person );
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//end::associations-not-found-persist-example[]
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} );
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doInJPA( this::entityManagerFactory, entityManager -> {
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//tag::associations-not-found-find-example[]
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Person person = entityManager.find( Person.class, 1L );
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assertEquals( "New York", person.getCity().getName() );
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//end::associations-not-found-find-example[]
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//tag::associations-not-found-non-existing-persist-example[]
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person.setCityName( "Atlantis" );
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//end::associations-not-found-non-existing-persist-example[]
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} );
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doInJPA( this::entityManagerFactory, entityManager -> {
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//tag::associations-not-found-non-existing-find-example[]
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Person person = entityManager.find( Person.class, 1L );
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assertEquals( "Atlantis", person.getCityName() );
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assertNull( null, person.getCity() );
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//end::associations-not-found-non-existing-find-example[]
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} );
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}
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//tag::associations-not-found-domain-model-example[]
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@Entity
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@Table( name = "Person" )
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public static class Person {
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@Id
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private Long id;
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private String name;
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private String cityName;
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@ManyToOne( fetch = FetchType.LAZY )
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@NotFound ( action = NotFoundAction.IGNORE )
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@JoinColumn(
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name = "cityName",
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referencedColumnName = "name",
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insertable = false,
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updatable = false
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)
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private City city;
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//Getters and setters are omitted for brevity
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//end::associations-not-found-domain-model-example[]
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public Long getId() {
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return id;
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}
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public void setId(Long id) {
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this.id = id;
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}
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public String getName() {
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return name;
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}
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public void setName(String name) {
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this.name = name;
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}
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public String getCityName() {
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return cityName;
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}
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public void setCityName(String cityName) {
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this.cityName = cityName;
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this.city = null;
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}
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public City getCity() {
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return city;
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}
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//tag::associations-not-found-domain-model-example[]
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}
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@Entity
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@Table( name = "City" )
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public static class City implements Serializable {
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@Id
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@GeneratedValue
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private Long id;
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private String name;
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//Getters and setters are omitted for brevity
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//end::associations-not-found-domain-model-example[]
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public Long getId() {
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return id;
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}
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public void setId(Long id) {
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this.id = id;
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}
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public String getName() {
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return name;
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}
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public void setName(String name) {
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this.name = name;
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}
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//tag::associations-not-found-domain-model-example[]
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}
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//end::associations-not-found-domain-model-example[]
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}
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