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BAEL-4887: fetching multiple entities in JPA query (#10803)

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This commit is contained in:
Maciej Główka 2021-05-25 21:48:22 +02:00 committed by GitHub
parent c24379b927
commit 27c53fd6de
6 changed files with 240 additions and 0 deletions
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43
persistence-modules/java-jpa-3/src/main/java/com/baeldung/jpa/returnmultipleentities/Channel.java Normal file
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@ -0,0 +1,43 @@
package com.baeldung.jpa.returnmultipleentities;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import java.util.Objects;
@Entity
public class Channel {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
private String code;
private Long subscriptionId;
public void setCode(String code) {
this.code = code;
}
public String getCode() {
return code;
}
public void setSubscriptionId(Long subscriptionId) {
this.subscriptionId = subscriptionId;
}
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
Channel channel = (Channel) o;
return Objects.equals(id, channel.id) && Objects.equals(code, channel.code) && Objects.equals(subscriptionId, channel.subscriptionId);
}
@Override
public int hashCode() {
return Objects.hash(id, code, subscriptionId);
}
}

23
persistence-modules/java-jpa-3/src/main/java/com/baeldung/jpa/returnmultipleentities/ReportRepository.java Normal file
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package com.baeldung.jpa.returnmultipleentities;
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;
import javax.persistence.Query;
import java.util.List;
public class ReportRepository {
private final EntityManagerFactory emf;
public ReportRepository() {
emf = Persistence.createEntityManagerFactory("jpa-h2-return-multiple-entities");
}
public List<Object[]> find(String email) {
EntityManager entityManager = emf.createEntityManager();
Query query = entityManager.createQuery("SELECT c, s, u FROM Channel c, Subscription s, User u WHERE c.subscriptionId = s.id AND s.id = u.subscriptionId AND u.email=:email");
query.setParameter("email", email);
return query.getResultList();
}
}

41
persistence-modules/java-jpa-3/src/main/java/com/baeldung/jpa/returnmultipleentities/Subscription.java Normal file
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@ -0,0 +1,41 @@
package com.baeldung.jpa.returnmultipleentities;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import java.util.Objects;
@Entity
public class Subscription {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
private String code;
public void setCode(String code) {
this.code = code;
}
public String getCode() {
return code;
}
public Long getId() {
return id;
}
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
Subscription subscription = (Subscription) o;
return Objects.equals(id, subscription.id) && Objects.equals(code, subscription.code);
}
@Override
public int hashCode() {
return Objects.hash(id, code);
}
}

29
persistence-modules/java-jpa-3/src/main/java/com/baeldung/jpa/returnmultipleentities/User.java Normal file
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@ -0,0 +1,29 @@
package com.baeldung.jpa.returnmultipleentities;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
@Entity
public class User {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
private String email;
private Long subscriptionId;
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
public void setSubscriptionId(Long subscriptionId) {
this.subscriptionId = subscriptionId;
}
}

20
persistence-modules/java-jpa-3/src/main/resources/META-INF/persistence.xml
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@ -113,4 +113,24 @@
<property name="hibernate.temp.use_jdbc_metadata_defaults" value="false"/>
</properties>
</persistence-unit>
<persistence-unit name="jpa-h2-return-multiple-entities">
<provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
<class>com.baeldung.jpa.returnmultipleentities.Channel</class>
<class>com.baeldung.jpa.returnmultipleentities.Subscription</class>
<class>com.baeldung.jpa.returnmultipleentities.User</class>
<class>com.baeldung.jpa.returnmultipleentities.ReportRepository</class>
<exclude-unlisted-classes>true</exclude-unlisted-classes>
<properties>
<property name="javax.persistence.jdbc.driver" value="org.h2.Driver"/>
<property name="javax.persistence.jdbc.url" value="jdbc:h2:mem:test"/>
<property name="javax.persistence.jdbc.user" value="sa"/>
<property name="javax.persistence.jdbc.password" value=""/>
<property name="javax.persistence.jdbc.driver" value="org.h2.Driver"/>
<property name="hibernate.dialect" value="org.hibernate.dialect.H2Dialect"/>
<property name="hibernate.hbm2ddl.auto" value="create-drop"/>
<property name="hibernate.show_sql" value="true"/>
<property name="hibernate.format_sql" value="true"/>
<property name="hibernate.temp.use_jdbc_metadata_defaults" value="false"/>
</properties>
</persistence-unit>
</persistence>

84
persistence-modules/java-jpa-3/src/test/java/com/baeldung/jpa/returnmultipleentities/ReturnMultipleEntitiesIntegrationTest.java Normal file
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package com.baeldung.jpa.returnmultipleentities;
import org.junit.Before;
import org.junit.Test;
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;
import java.util.List;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.fail;
public class ReturnMultipleEntitiesIntegrationTest {
private static EntityManagerFactory factory;
private static EntityManager entityManager;
private ReportRepository reportRepository;
@Before
public void setup() {
factory = Persistence.createEntityManagerFactory("jpa-h2-return-multiple-entities");
entityManager = factory.createEntityManager();
reportRepository = new ReportRepository();
populateH2DB();
}
@Test
public void whenQueryingForMultipleEntitiesInOneQuery_thenJPAReturnsMultipleEntitiesInCorrectOrder() {
List<Object[]> reportDetails = reportRepository.find("user1@gmail.com");
assertEquals(2, reportDetails.size());
for (Object[] reportDetail : reportDetails) {
assertEquals(3, reportDetail.length);
Channel channel = (Channel) reportDetail[0];
Subscription subscription = (Subscription) reportDetail[1];
User user = (User) reportDetail[2];
assertEquals("single", subscription.getCode());
assertEquals("user1@gmail.com", user.getEmail());
if (!("eurosport".equals(channel.getCode()) || "hbo".equals(channel.getCode()))) {
fail();
}
}
}
private static void populateH2DB() {
entityManager.getTransaction().begin();
Subscription single = new Subscription();
single.setCode("single");
Subscription family = new Subscription();
family.setCode("family");
entityManager.persist(single);
entityManager.persist(family);
Channel bbc = new Channel();
bbc.setCode("bbc");
bbc.setSubscriptionId(family.getId());
Channel eurosport = new Channel();
eurosport.setCode("eurosport");
eurosport.setSubscriptionId(single.getId());
Channel hbo = new Channel();
hbo.setCode("hbo");
hbo.setSubscriptionId(single.getId());
entityManager.persist(bbc);
entityManager.persist(eurosport);
entityManager.persist(hbo);
User user1 = new User();
user1.setEmail("user1@gmail.com");
user1.setSubscriptionId(single.getId());
entityManager.persist(user1);
entityManager.getTransaction().commit();
}
}