#206 - Added more projection examples in JPA.

Added another one that shows projections can be wrapped into an Optional.

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

@@ -16,6 +16,7 @@
 package example.springdata.jpa.projections;
 
 import java.util.Collection;
+import java.util.Optional;
 
 import org.springframework.beans.factory.annotation.Value;
 import org.springframework.data.domain.Page;
@@ -104,4 +105,12 @@ public interface CustomerRepository extends CrudRepository<Customer, Long> {
 	 */
 	@Query("select new example.springdata.jpa.projections.CustomerDto(c.firstname) from Customer c where c.firstname = ?1")
 	Collection<CustomerDto> findDtoWithConstructorExpression(String firstname);
+
+	/**
+	 * A projection wrapped into an {@link Optional}.
+	 * 
+	 * @param lastname
+	 * @return
+	 */
+	Optional<CustomerProjection> findOptionalProjectionByLastname(String lastname);
 }

jpa/example/src/test/java/example/springdata/jpa/projections/CustomerRepositoryIntegrationTest.java

@@ -134,4 +134,9 @@ public class CustomerRepositoryIntegrationTest {
 
 		assertThat(page.getContent().get(0).getFirstname(), is("Carter"));
 	}
+
+	@Test
+	public void appliesProjectionToOptional() {
+		assertThat(customers.findOptionalProjectionByLastname("Beauford").isPresent(), is(true));
+	}
 }