DATAJPA-1115 - Adapt to QuerydslPredicateExecutor API changes.

We now return Optional<T> for findOne(Predicate).

Original pull request: #202.
Related ticket: DATACMNS-1059.

src/main/java/org/springframework/data/jpa/repository/support/QuerydslJpaRepository.java

@@ -18,10 +18,13 @@ package org.springframework.data.jpa.repository.support;
 import java.io.Serializable;
 import java.util.List;
 import java.util.Map.Entry;
+import java.util.Optional;
 
 import javax.persistence.EntityManager;
 import javax.persistence.LockModeType;
 
+import com.querydsl.core.NonUniqueResultException;
+import org.springframework.dao.IncorrectResultSizeDataAccessException;
 import org.springframework.data.domain.Page;
 import org.springframework.data.domain.Pageable;
 import org.springframework.data.domain.Sort;
@@ -94,8 +97,13 @@ public class QuerydslJpaRepository<T, ID extends Serializable> extends SimpleJpa
 	 * @see org.springframework.data.querydsl.QuerydslPredicateExecutor#findOne(com.mysema.query.types.Predicate)
 	 */
 	@Override
-	public T findOne(Predicate predicate) {
-		return createQuery(predicate).select(path).fetchOne();
+	public Optional<T> findOne(Predicate predicate) {
+
+		try {
+			return Optional.ofNullable(createQuery(predicate).select(path).fetchOne());
+		} catch (NonUniqueResultException ex) {
+			throw new IncorrectResultSizeDataAccessException(ex.getMessage(), 1, ex);
+		}
 	}
 
 	/*

src/test/java/org/springframework/data/jpa/repository/sample/RoleRepository.java

@@ -59,7 +59,7 @@ public interface RoleRepository extends CrudRepository<Role, Integer>, QuerydslP
 	@Override
 	@Lock(LockModeType.READ)
 	@QueryHints(@QueryHint(name = "foo", value = "bar"))
-	Role findOne(Predicate predicate);
+	Optional<Role> findOne(Predicate predicate);
 
 	// DATAJPA-509
 	long countByName(String name);

src/test/java/org/springframework/data/jpa/repository/support/QuerydslJpaRepositoryTests.java

@@ -23,10 +23,12 @@ import java.util.List;
 import javax.persistence.EntityManager;
 import javax.persistence.PersistenceContext;
 
+import org.assertj.core.api.Assertions;
 import org.joda.time.LocalDate;
 import org.junit.Before;
 import org.junit.Test;
 import org.junit.runner.RunWith;
+import org.springframework.dao.IncorrectResultSizeDataAccessException;
 import org.springframework.data.domain.Page;
 import org.springframework.data.domain.PageRequest;
 import org.springframework.data.domain.Pageable;
@@ -54,6 +56,7 @@ import com.querydsl.core.types.dsl.PathBuilderFactory;
  * @author Oliver Gierke
  * @author Thomas Darimont
  * @author Mark Paluch
+ * @author Christoph Strobl
  */
 @RunWith(SpringJUnit4ClassRunner.class)
 @ContextConfiguration({ "classpath:infrastructure.xml" })
@@ -336,4 +339,19 @@ public class QuerydslJpaRepositoryTests {
 		assertThat(secondPage.getContent(), hasSize(0));
 		assertThat(secondPage.getTotalElements(), is(3L));
 	}
+
+	@Test // DATAJPA-1115
+	public void findOneWithPredicateReturnsResultCorrectly() {
+		Assertions.assertThat(repository.findOne(user.eq(dave))).contains(dave);
+	}
+
+	@Test // DATAJPA-1115
+	public void findOneWithPredicateReturnsOptionalEmptyWhenNoDataFound() {
+		Assertions.assertThat(repository.findOne(user.firstname.eq("batman"))).isNotPresent();
+	}
+
+	@Test(expected = IncorrectResultSizeDataAccessException.class) // DATAJPA-1115
+	public void findOneWithPredicateThrowsExceptionForNonUniqueResults() {
+		repository.findOne(user.emailAddress.contains("com"));
+	}
 }