Merge pull request eugenp#8246 from kumar-devender/master

Persistence context example

Author: sjmillington

persistence-modules/spring-boot-persistence/src/main/java/com/baeldung/persistencecontext/PersistenceContextDemoApplication.java

@@ -0,0 +1,13 @@
+package com.baeldung.persistencecontext;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.context.annotation.ComponentScan;
+
+@SpringBootApplication
+@ComponentScan(basePackages="com.baeldung.persistencecontext")
+public class PersistenceContextDemoApplication {
+    public static void main(String[] args) {
+        SpringApplication.run(PersistenceContextDemoApplication.class, args);
+    }
+}

persistence-modules/spring-boot-persistence/src/main/java/com/baeldung/persistencecontext/entity/User.java

@@ -0,0 +1,36 @@
+package com.baeldung.persistencecontext.entity;
+
+import javax.persistence.Entity;
+import javax.persistence.Id;
+
+@Entity
+public class User {
+
+    @Id
+    private Long id;
+    private String name;
+    private String role;
+
+    public User() {
+
+    }
+
+    public User(Long id, String name, String role) {
+        this.id = id;
+        this.name = name;
+        this.role = role;
+    }
+
+    public Long getId() {
+        return id;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public String getRole() {
+        return role;
+    }
+
+}

persistence-modules/spring-boot-persistence/src/main/java/com/baeldung/persistencecontext/service/ExtendedPersistenceContextUserService.java

@@ -0,0 +1,33 @@
+package com.baeldung.persistencecontext.service;
+
+import javax.persistence.EntityManager;
+import javax.persistence.PersistenceContext;
+import javax.persistence.PersistenceContextType;
+import javax.transaction.Transactional;
+
+import org.springframework.stereotype.Component;
+
+import com.baeldung.persistencecontext.entity.User;
+
+@Component
+public class ExtendedPersistenceContextUserService {
+
+    @PersistenceContext(type = PersistenceContextType.EXTENDED)
+    private EntityManager entityManager;
+
+    @Transactional
+    public User insertWithTransaction(User user) {
+        entityManager.persist(user);
+        return user;
+    }
+
+    public User insertWithoutTransaction(User user) {
+        entityManager.persist(user);
+        return user;
+    }
+
+    public User find(long id) {
+        User user = entityManager.find(User.class, id);
+        return user;
+    }
+}

persistence-modules/spring-boot-persistence/src/main/java/com/baeldung/persistencecontext/service/TransctionPersistenceContextUserService.java

@@ -0,0 +1,32 @@
+package com.baeldung.persistencecontext.service;
+
+
+import javax.persistence.EntityManager;
+import javax.persistence.PersistenceContext;
+import javax.transaction.Transactional;
+
+import org.springframework.stereotype.Component;
+
+import com.baeldung.persistencecontext.entity.User;
+
+@Component
+public class TransctionPersistenceContextUserService {
+
+    @PersistenceContext
+    private EntityManager entityManager;
+    
+    @Transactional
+    public User insertWithTransaction(User user) {
+        entityManager.persist(user);
+        return user;
+    }
+    
+    public User insertWithoutTransaction(User user) {
+        entityManager.persist(user);
+        return user;
+    }
+    
+    public User find(long id) {
+        return entityManager.find(User.class, id);
+    }
+}

persistence-modules/spring-boot-persistence/src/test/java/com/baeldung/persistencecontext/PersistenceContextIntegrationTest.java

@@ -0,0 +1,90 @@
+package com.baeldung.persistencecontext;
+
+import com.baeldung.persistencecontext.entity.User;
+import com.baeldung.persistencecontext.service.ExtendedPersistenceContextUserService;
+import com.baeldung.persistencecontext.service.TransctionPersistenceContextUserService;
+
+import javax.persistence.EntityExistsException;
+import javax.persistence.TransactionRequiredException;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.test.context.junit4.SpringRunner;
+
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNull;
+
+@RunWith(SpringRunner.class)
+@SpringBootTest(classes = com.baeldung.persistencecontext.PersistenceContextDemoApplication.class)
+public class PersistenceContextIntegrationTest {
+
+    @Autowired
+    private TransctionPersistenceContextUserService transctionPersistenceContext;
+    @Autowired
+    private ExtendedPersistenceContextUserService extendedPersistenceContext;
+
+    @Test
+    public void testThatWhenUserSavedWithTransctionPersistenceContextThenUserShouldGetSavedInDB() {
+        User user = new User(121L, "Devender", "admin");
+        transctionPersistenceContext.insertWithTransaction(user);
+
+        User userFromTransctionPersistenceContext = transctionPersistenceContext.find(user.getId());
+        assertNotNull(userFromTransctionPersistenceContext);
+
+        User userFromExtendedPersistenceContext = extendedPersistenceContext.find(user.getId());
+        assertNotNull(userFromExtendedPersistenceContext);
+    }
+
+    @Test(expected = TransactionRequiredException.class)
+    public void testThatUserSaveWithoutTransactionThrowException() {
+        User user = new User(122L, "Devender", "admin");
+        transctionPersistenceContext.insertWithoutTransaction(user);
+    }
+
+    @Test
+    public void testThatWhenUserSavedWithExtendedPersistenceContextWithoutTransactionThenUserShouldGetCached() {
+        User user = new User(123L, "Devender", "admin");
+        extendedPersistenceContext.insertWithoutTransaction(user);
+
+        User userFromExtendedPersistenceContext = extendedPersistenceContext.find(user.getId());
+        assertNotNull(userFromExtendedPersistenceContext);
+
+        User userFromTransctionPersistenceContext = transctionPersistenceContext.find(user.getId());
+        assertNull(userFromTransctionPersistenceContext);
+    }
+
+    @Test(expected = EntityExistsException.class)
+    public void testThatPersistUserWithSameIdentifierThrowException() {
+        User user1 = new User(126L, "Devender", "admin");
+        User user2 = new User(126L, "Devender", "admin");
+        extendedPersistenceContext.insertWithoutTransaction(user1);
+        extendedPersistenceContext.insertWithoutTransaction(user2);
+    }
+
+    @Test
+    public void testThatWhenUserSavedWithExtendedPersistenceContextWithTransactionThenUserShouldSaveEntityIntoDB() {
+        User user = new User(127L, "Devender", "admin");
+        extendedPersistenceContext.insertWithTransaction(user);
+
+        User userFromDB = transctionPersistenceContext.find(user.getId());
+        assertNotNull(userFromDB);
+    }
+
+    @Test
+    public void testThatWhenUserSavedWithExtendedPersistenceContextWithTransactionThenUserShouldFlushCachedEntityIntoDB() {
+        User user1 = new User(124L, "Devender", "admin");
+        extendedPersistenceContext.insertWithoutTransaction(user1);
+
+        User user2 = new User(125L, "Devender", "admin");
+        extendedPersistenceContext.insertWithTransaction(user2);
+
+        User user1FromTransctionPersistenceContext = transctionPersistenceContext.find(user1.getId());
+        assertNotNull(user1FromTransctionPersistenceContext);
+
+        User user2FromTransctionPersistenceContext = transctionPersistenceContext.find(user2.getId());
+        assertNotNull(user2FromTransctionPersistenceContext);
+    }
+
+}