Added showcase for JDK 8's Optional support on repository methods.

Abbreviated JPA sample module folder names. Renamed the Java 8 auditing sample module to Java 8 module as it not only contains samples for auditing anymore.

jpa/example/pom.xml

@@ -20,6 +20,12 @@
 			<groupId>org.springframework</groupId>
 			<artifactId>spring-aspects</artifactId>
 		</dependency>
+		
+		<dependency>
+			<groupId>com.google.guava</groupId>
+			<artifactId>guava</artifactId>
+			<version>16.0.1</version>
+		</dependency>
 
 	</dependencies>
 

jpa/example/src/main/java/example/springdata/jpa/simple/SimpleUserRepository.java

@@ -21,6 +21,8 @@ import org.springframework.data.jpa.repository.Query;
 import org.springframework.data.repository.CrudRepository;
 import org.springframework.data.repository.query.Param;
 
+import com.google.common.base.Optional;
+
 /**
  * Simple repository interface for {@link User} instances. The interface is used to declare so called query methods,
  * methods to retrieve single entities or collections of them.
@@ -39,6 +41,8 @@ public interface SimpleUserRepository extends CrudRepository<User, Long> {
 	 */
 	User findByTheUsersName(String username);
 
+	Optional<User> findByUsername(String username);
+
 	/**
 	 * Find all users with the given lastname. This method will be translated into a query by constructing it directly
 	 * from the method name as there is no other query declared.

jpa/example/src/test/java/example/springdata/jpa/simple/SimpleUserRepositoryTests.java

@@ -15,6 +15,7 @@
  */
 package example.springdata.jpa.simple;
 
+import static org.hamcrest.CoreMatchers.*;
 import static org.junit.Assert.*;
 
 import java.util.List;
@@ -27,10 +28,6 @@ import org.springframework.test.context.ContextConfiguration;
 import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
 import org.springframework.transaction.annotation.Transactional;
 
-import example.springdata.jpa.simple.SimpleConfiguration;
-import example.springdata.jpa.simple.SimpleUserRepository;
-import example.springdata.jpa.simple.User;
-
 /**
  * Intergration test showing the basic usage of {@link SimpleUserRepository}.
  * 
@@ -47,6 +44,7 @@ public class SimpleUserRepositoryTests {
 
 	@Before
 	public void setUp() {
+
 		user = new User();
 		user.setUsername("foobar");
 		user.setFirstname("firstname");
@@ -58,7 +56,7 @@ public class SimpleUserRepositoryTests {
 
 		user = repository.save(user);
 
-		assertEquals(user, repository.findOne(user.getId()));
+		assertThat(repository.findOne(user.getId()), is(user));
 	}
 
 	@Test
@@ -68,8 +66,8 @@ public class SimpleUserRepositoryTests {
 
 		List<User> users = repository.findByLastname("lastname");
 
-		assertNotNull(users);
-		assertTrue(users.contains(user));
+		assertThat(users, is(notNullValue()));
+		assertThat(users.contains(user), is(true));
 	}
 
 	@Test
@@ -79,6 +77,16 @@ public class SimpleUserRepositoryTests {
 
 		List<User> users = repository.findByFirstnameOrLastname("lastname");
 
-		assertTrue(users.contains(user));
+		assertThat(users.contains(user), is(true));
+	}
+
+	@Test
+	public void useGuavaOptionalInsteadOfNulls() {
+
+		assertThat(repository.findByUsername("foobar").isPresent(), is(false));
+
+		repository.save(user);
+
+		assertThat(repository.findByUsername("foobar").isPresent(), is(true));
 	}
 }

jpa/java8/README.md

@@ -0,0 +1,23 @@
+# Spring Data - Java 8 examples
+
+This project contains samples of Java 8 specific features of Spring Data (JPA).
+
+## Support for JDK 8's `Optional` for repository methods
+
+```java
+interface CustomerRepository extends Repository<Customer, Long> {
+
+  // CRUD method using Optional
+  Optional<Customer> findOne(Long id);
+
+  // Query method using Optional
+  Optional<Customer> findByLastname(String lastname);
+}
+```
+
+* `CustomerRepository.findOne(Long)` effectively "overrides" the default `CrudRepository.findOne(…)` to return `Optional.empty()` instead of `null` in case no uniqe element satisfying the query can be found.
+* `CustomerRepository.findByLastname(…)` does the same for a normal query method.
+
+## Support for JDK 8's date/time types in the auditing sub-system
+
+* `Customer` extends `AbstractEntity` which contains fields of JDK 8's new date/time API and those can be populated the same way legacy types like `Date` and `Calendar` can.

jpa/java8/pom.xml

@@ -8,8 +8,8 @@
 		<version>1.0.0.BUILD-SNAPSHOT</version>
 	</parent>
 
-	<artifactId>spring-data-jpa-java8-auditing</artifactId>
-	<name>Spring Data JPA - Auditing on Java 8</name>
+	<artifactId>spring-data-jpa-java8</artifactId>
+	<name>Spring Data JPA - Java 8 specific features</name>
 	
 	<dependencies>
 		

jpa/java8/src/main/java/example/springdata/jpa/java8/AuditingConfiguration.java

@@ -21,6 +21,7 @@ import org.springframework.data.jpa.repository.config.EnableJpaAuditing;
 
 @Configuration
 @EnableAutoConfiguration
-@EnableJpaAuditing class AuditingConfiguration {
+@EnableJpaAuditing
+class AuditingConfiguration {
 
-}
+}

jpa/java8/src/main/java/example/springdata/jpa/java8/CustomerRepository.java

@@ -15,11 +15,25 @@
  */
 package example.springdata.jpa.java8;
 
+import java.util.Optional;
+
 import org.springframework.data.repository.CrudRepository;
+import org.springframework.data.repository.Repository;
 
 /**
+ * Repository to manage {@link Customer} instances.
+ * 
  * @author Oliver Gierke
  */
-public interface CustomerRepository extends CrudRepository<Customer, Long> {
+public interface CustomerRepository extends Repository<Customer, Long> {
 
+	/**
+	 * Special customization of {@link CrudRepository#findOne(java.io.Serializable)} to return a JDK 8 {@link Optional}.
+	 * 
+	 * @param id
+	 * @return
+	 */
+	Optional<Customer> findOne(Long id);
+
+	<S extends Customer> S save(S customer);
 }

jpa/java8/src/test/java/example/springdata/jpa/java8/Java8IntegrationTests.java

@@ -18,11 +18,14 @@ package example.springdata.jpa.java8;
 import static org.hamcrest.CoreMatchers.*;
 import static org.junit.Assert.*;
 
+import java.util.Optional;
+
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.test.context.ContextConfiguration;
 import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
+import org.springframework.transaction.annotation.Transactional;
 
 /**
  * Integration test to show the usage of Java 8 date time APIs with Spring Data JPA auditing.
@@ -31,10 +34,20 @@ import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
  */
 @RunWith(SpringJUnit4ClassRunner.class)
 @ContextConfiguration(classes = AuditingConfiguration.class)
-public class Java8AuditingIntegrationTests {
+@Transactional
+public class Java8IntegrationTests {
 
 	@Autowired CustomerRepository repository;
 
+	@Test
+	public void providesFindOneWithOptional() {
+
+		Customer carter = repository.save(new Customer("Carter", "Beauford"));
+
+		assertThat(repository.findOne(carter.id).isPresent(), is(true));
+		assertThat(repository.findOne(carter.id + 1), is(Optional.<Customer> empty()));
+	}
+
 	@Test
 	public void auditingSetsJdk8DateTimeTypes() {
 

jpa/pom.xml

@@ -17,14 +17,14 @@
 	<inceptionYear>2011</inceptionYear>
 
 	<modules>
-		<module>spring-data-jpa-example</module>
-		<module>spring-data-jpa-showcase</module>
-		<module>spring-data-jpa-interceptors</module>
-		<module>spring-data-jpa-java8-auditing</module>
+		<module>example</module>
+		<module>showcase</module>
+		<module>interceptors</module>
+		<module>java8</module>
 	</modules>
 
 	<properties>
-		<spring-data-jpa.version>1.5.1.RELEASE</spring-data-jpa.version>
+		<spring-data-jpa.version>1.6.0.BUILD-SNAPSHOT</spring-data-jpa.version>
 		<hibernate-entitymanager.version>4.3.4.Final</hibernate-entitymanager.version>
 	</properties>
 
@@ -47,4 +47,11 @@
 
 	</dependencies>
 
+	<repositories>
+		<repository>
+			<id>spring-libs-snapshot</id>
+			<url>http:/repo.spring.io/libs-snapshot</url>
+		</repository>
+	</repositories>
+
 </project>