Add BAEL-2067 DomainEvents examples

spring-data-jpa/pom.xml

@@ -41,6 +41,26 @@
             <artifactId>guava</artifactId>
             <version>21.0</version>
         </dependency>
+        
+        <!-- JUnit Jupiter dependencies -->
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-api</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-engine</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <!-- JUnit platform launcher -->
+        <!-- To be able to run tests from IDE directly -->
+        <dependency>
+            <groupId>org.junit.platform</groupId>
+            <artifactId>junit-platform-launcher</artifactId>
+            <version>${junit-platform.version}</version>
+            <scope>test</scope>
+        </dependency>
     </dependencies>
 
 </project>

spring-data-jpa/src/main/java/com/baeldung/Application.java

@@ -1,11 +1,11 @@
 package com.baeldung;
 
-import com.baeldung.dao.repositories.impl.ExtendedRepositoryImpl;
 import org.springframework.boot.SpringApplication;
 import org.springframework.boot.autoconfigure.SpringBootApplication;
-import org.springframework.boot.autoconfigure.domain.EntityScan;
 import org.springframework.data.jpa.repository.config.EnableJpaRepositories;
 
+import com.baeldung.dao.repositories.impl.ExtendedRepositoryImpl;
+
 @SpringBootApplication
 @EnableJpaRepositories(repositoryBaseClass = ExtendedRepositoryImpl.class)
 public class Application {

spring-data-jpa/src/main/java/com/baeldung/ddd/event/Aggregate.java

@@ -0,0 +1,46 @@
+/**
+ *
+ */
+package com.baeldung.ddd.event;
+
+import javax.persistence.Entity;
+import javax.persistence.Id;
+import javax.persistence.Transient;
+
+import org.springframework.context.ApplicationEventPublisher;
+
+@Entity
+class Aggregate {
+    @Transient
+    private ApplicationEventPublisher eventPublisher;
+    @Id
+    private long id;
+
+    private Aggregate() {
+    }
+
+    Aggregate(long id, ApplicationEventPublisher eventPublisher) {
+        this.id = id;
+        this.eventPublisher = eventPublisher;
+    }
+
+    /* (non-Javadoc)
+     * @see java.lang.Object#toString()
+     */
+    @Override
+    public String toString() {
+        return "DomainEntity [id=" + id + "]";
+    }
+
+    void domainOperation() {
+        // some business logic
+        if (eventPublisher != null) {
+            eventPublisher.publishEvent(new DomainEvent());
+        }
+    }
+
+    long getId() {
+        return id;
+    }
+
+}

spring-data-jpa/src/main/java/com/baeldung/ddd/event/Aggregate2.java

@@ -0,0 +1,44 @@
+/**
+ *
+ */
+package com.baeldung.ddd.event;
+
+import java.util.ArrayList;
+import java.util.Collection;
+
+import javax.persistence.Entity;
+import javax.persistence.GeneratedValue;
+import javax.persistence.Id;
+import javax.persistence.Transient;
+
+import org.springframework.data.domain.AfterDomainEventPublication;
+import org.springframework.data.domain.DomainEvents;
+
+@Entity
+public class Aggregate2 {
+    @Transient
+    private final Collection<DomainEvent> domainEvents;
+    @Id
+    @GeneratedValue
+    private long id;
+
+    public Aggregate2() {
+        domainEvents = new ArrayList<>();
+    }
+
+    @AfterDomainEventPublication
+    public void clearEvents() {
+        domainEvents.clear();
+    }
+
+    public void domainOperation() {
+        // some domain operation
+        domainEvents.add(new DomainEvent());
+    }
+
+    @DomainEvents
+    public Collection<DomainEvent> events() {
+        return domainEvents;
+    }
+
+}

spring-data-jpa/src/main/java/com/baeldung/ddd/event/Aggregate2Repository.java

@@ -0,0 +1,10 @@
+/**
+ *
+ */
+package com.baeldung.ddd.event;
+
+import org.springframework.data.repository.CrudRepository;
+
+public interface Aggregate2Repository extends CrudRepository<Aggregate2, Long> {
+
+}

spring-data-jpa/src/main/java/com/baeldung/ddd/event/Aggregate3.java

@@ -0,0 +1,23 @@
+/**
+ *
+ */
+package com.baeldung.ddd.event;
+
+import javax.persistence.Entity;
+import javax.persistence.GeneratedValue;
+import javax.persistence.Id;
+
+import org.springframework.data.domain.AbstractAggregateRoot;
+
+@Entity
+public class Aggregate3 extends AbstractAggregateRoot<Aggregate3> {
+    @Id
+    @GeneratedValue
+    private long id;
+
+    public void domainOperation() {
+        // some domain operation
+        registerEvent(new DomainEvent());
+    }
+
+}

spring-data-jpa/src/main/java/com/baeldung/ddd/event/Aggregate3Repository.java

@@ -0,0 +1,14 @@
+/**
+ * 
+ */
+package com.baeldung.ddd.event;
+
+import org.springframework.data.repository.CrudRepository;
+
+/**
+ * @author goobar
+ *
+ */
+public interface Aggregate3Repository extends CrudRepository<Aggregate3, Long> {
+
+}

spring-data-jpa/src/main/java/com/baeldung/ddd/event/AggregateRepository.java

@@ -0,0 +1,10 @@
+/**
+ *
+ */
+package com.baeldung.ddd.event;
+
+import org.springframework.data.repository.CrudRepository;
+
+public interface AggregateRepository extends CrudRepository<Aggregate, Long> {
+
+}

spring-data-jpa/src/main/java/com/baeldung/ddd/event/DddConfig.java

@@ -0,0 +1,15 @@
+/**
+ *
+ */
+package com.baeldung.ddd.event;
+
+import org.springframework.boot.SpringBootConfiguration;
+import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+import org.springframework.context.annotation.PropertySource;
+
+@SpringBootConfiguration
+@EnableAutoConfiguration
+@PropertySource("classpath:/ddd.properties")
+public class DddConfig {
+
+}

spring-data-jpa/src/main/java/com/baeldung/ddd/event/DomainEvent.java

@@ -0,0 +1,8 @@
+/**
+ *
+ */
+package com.baeldung.ddd.event;
+
+class DomainEvent {
+
+}

spring-data-jpa/src/main/java/com/baeldung/ddd/event/DomainService.java

@@ -0,0 +1,31 @@
+/**
+ *
+ */
+package com.baeldung.ddd.event;
+
+import javax.transaction.Transactional;
+
+import org.springframework.context.ApplicationEventPublisher;
+import org.springframework.stereotype.Service;
+
+@Service
+public class DomainService {
+    private final ApplicationEventPublisher eventPublisher;
+    private final AggregateRepository repository;
+
+    public DomainService(AggregateRepository repository, ApplicationEventPublisher eventPublisher) {
+        this.repository = repository;
+        this.eventPublisher = eventPublisher;
+    }
+
+    @Transactional
+    public void serviceDomainOperation(long entityId) {
+        repository.findById(entityId)
+            .ifPresent(entity -> {
+                entity.domainOperation();
+                repository.save(entity);
+                eventPublisher.publishEvent(new DomainEvent());
+            });
+    }
+
+}

spring-data-jpa/src/main/resources/ddd.properties

@@ -0,0 +1 @@
+spring.datasource.initialization-mode=never

spring-data-jpa/src/main/resources/persistence-multiple-db.properties

@@ -3,7 +3,7 @@ jdbc.driverClassName=org.h2.Driver
 user.jdbc.url=jdbc:h2:mem:spring_jpa_user;DB_CLOSE_DELAY=-1;INIT=CREATE SCHEMA IF NOT EXISTS USERS
 product.jdbc.url=jdbc:h2:mem:spring_jpa_product;DB_CLOSE_DELAY=-1;INIT=CREATE SCHEMA IF NOT EXISTS PRODUCTS
 jdbc.user=sa
-jdbc.pass=
+jdbc.pass=sa
 
 # hibernate.X
 hibernate.dialect=org.hibernate.dialect.H2Dialect

spring-data-jpa/src/main/resources/persistence.properties

@@ -2,7 +2,7 @@
 jdbc.driverClassName=org.h2.Driver
 jdbc.url=jdbc:h2:mem:db;DB_CLOSE_DELAY=-1;INIT=CREATE SCHEMA IF NOT EXISTS USERS
 jdbc.user=sa
-jdbc.pass=
+jdbc.pass=sa
 
 # hibernate.X
 hibernate.dialect=org.hibernate.dialect.H2Dialect

spring-data-jpa/src/test/java/com/baeldung/ddd/event/Aggregate2EventsIntegrationTest.java

@@ -0,0 +1,68 @@
+/**
+ *
+ */
+package com.baeldung.ddd.event;
+
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.boot.test.mock.mockito.MockBean;
+import org.springframework.test.context.junit.jupiter.SpringJUnitConfig;
+
+@SpringJUnitConfig
+@SpringBootTest
+class Aggregate2EventsIntegrationTest {
+    @MockBean
+    private TestEventHandler eventHandler;
+    @Autowired
+    private Aggregate2Repository repository;
+
+    // @formatter:off
+    @DisplayName("given aggregate with @AfterDomainEventPublication,"
+        + " when do domain operation and save twice,"
+        + " then an event is published only for the first time")
+    // @formatter:on
+    @Test
+    void afterDomainEvents() {
+        // given
+        Aggregate2 aggregate = new Aggregate2();
+
+        // when
+        aggregate.domainOperation();
+        repository.save(aggregate);
+        repository.save(aggregate);
+
+        // then
+        verify(eventHandler, times(1)).handleEvent(any(DomainEvent.class));
+    }
+
+    @BeforeEach
+    void beforeEach() {
+        repository.deleteAll();
+    }
+
+    // @formatter:off
+    @DisplayName("given aggregate with @DomainEvents,"
+        + " when do domain operation and save,"
+        + " then an event is published")
+    // @formatter:on
+    @Test
+    void domainEvents() {
+        // given
+        Aggregate2 aggregate = new Aggregate2();
+
+        // when
+        aggregate.domainOperation();
+        repository.save(aggregate);
+
+        // then
+        verify(eventHandler, times(1)).handleEvent(any(DomainEvent.class));
+    }
+
+}

spring-data-jpa/src/test/java/com/baeldung/ddd/event/Aggregate3EventsIntegrationTest.java

@@ -0,0 +1,63 @@
+/**
+ *
+ */
+package com.baeldung.ddd.event;
+
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.boot.test.mock.mockito.MockBean;
+import org.springframework.test.context.junit.jupiter.SpringJUnitConfig;
+
+@SpringJUnitConfig
+@SpringBootTest
+class Aggregate3EventsIntegrationTest {
+
+    @MockBean
+    private TestEventHandler eventHandler;
+    @Autowired
+    private Aggregate3Repository repository;
+
+    // @formatter:off
+    @DisplayName("given aggregate extending AbstractAggregateRoot,"
+        + " when do domain operation and save twice,"
+        + " then an event is published only for the first time")
+    // @formatter:on
+    @Test
+    void afterDomainEvents() {
+        // given
+        Aggregate3 aggregate = new Aggregate3();
+
+        // when
+        aggregate.domainOperation();
+        repository.save(aggregate);
+        repository.save(aggregate);
+
+        // then
+        verify(eventHandler, times(1)).handleEvent(any(DomainEvent.class));
+    }
+
+    // @formatter:off
+    @DisplayName("given aggregate extending AbstractAggregateRoot,"
+        + " when do domain operation and save,"
+        + " then an event is published")
+    // @formatter:on
+    @Test
+    void domainEvents() {
+        // given
+        Aggregate3 aggregate = new Aggregate3();
+
+        // when
+        aggregate.domainOperation();
+        repository.save(aggregate);
+
+        // then
+        verify(eventHandler, times(1)).handleEvent(any(DomainEvent.class));
+    }
+
+}

spring-data-jpa/src/test/java/com/baeldung/ddd/event/AggregateEventsIntegrationTest.java

@@ -0,0 +1,82 @@
+package com.baeldung.ddd.event;
+
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.verifyZeroInteractions;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.boot.test.context.TestConfiguration;
+import org.springframework.boot.test.mock.mockito.MockBean;
+import org.springframework.context.ApplicationEventPublisher;
+import org.springframework.context.annotation.Bean;
+import org.springframework.test.context.junit.jupiter.SpringJUnitConfig;
+
+@SpringJUnitConfig
+@SpringBootTest
+class AggregateEventsIntegrationTest {
+
+    @Autowired
+    private DomainService domainService;
+
+    @MockBean
+    private TestEventHandler eventHandler;
+    @Autowired
+    private ApplicationEventPublisher eventPublisher;
+    @Autowired
+    private AggregateRepository repository;
+
+    // @formatter:off
+    @DisplayName("given existing aggregate,"
+        + " when do domain operation directly on aggregate,"
+        + " then domain event is NOT published")
+    // @formatter:on
+    @Test
+    void aggregateEventsTest() {
+        Aggregate existingDomainEntity = new Aggregate(0, eventPublisher);
+        repository.save(existingDomainEntity);
+
+        // when
+        repository.findById(existingDomainEntity.getId())
+            .get()
+            .domainOperation();
+
+        // then
+        verifyZeroInteractions(eventHandler);
+    }
+
+    @BeforeEach
+    void beforeEach() {
+        repository.deleteAll();
+    }
+
+    // @formatter:off
+    @DisplayName("given existing aggregate,"
+        + " when do domain operation on service,"
+        + " then domain event is published")
+    // @formatter:on
+    @Test
+    void serviceEventsTest() {
+        Aggregate existingDomainEntity = new Aggregate(1, eventPublisher);
+        repository.save(existingDomainEntity);
+
+        // when
+        domainService.serviceDomainOperation(existingDomainEntity.getId());
+
+        // then
+        verify(eventHandler, times(1)).handleEvent(any(DomainEvent.class));
+    }
+
+    @TestConfiguration
+    public static class TestConfig {
+        @Bean
+        public DomainService domainService(AggregateRepository repository, ApplicationEventPublisher eventPublisher) {
+            return new DomainService(repository, eventPublisher);
+        }
+    }
+
+}

spring-data-jpa/src/test/java/com/baeldung/ddd/event/TestEventHandler.java

@@ -0,0 +1,12 @@
+/**
+ *
+ */
+package com.baeldung.ddd.event;
+
+import org.springframework.transaction.event.TransactionalEventListener;
+
+interface TestEventHandler {
+    @TransactionalEventListener
+    void handleEvent(DomainEvent event);
+
+}