Provide Specification allOf and anyOf operators to help compose Specifications..

See #1943.

Original PR: #404.

Author: daniel-shuy

spring-data-jpa/src/main/java/org/springframework/data/jpa/domain/Specification.java

@@ -21,6 +21,8 @@
 import jakarta.persistence.criteria.Root;
 
 import java.io.Serializable;
+import java.util.Arrays;
+import java.util.stream.StreamSupport;
 
 import org.springframework.lang.Nullable;
 
@@ -33,6 +35,7 @@
  * @author Sebastian Staudt
  * @author Mark Paluch
  * @author Jens Schauder
+ * @author Daniel Shuy
  */
 public interface Specification<T> extends Serializable {
 
@@ -98,4 +101,46 @@ default Specification<T> or(@Nullable Specification<T> other) {
 	 */
 	@Nullable
 	Predicate toPredicate(Root<T> root, CriteriaQuery<?> query, CriteriaBuilder criteriaBuilder);
+
+	/**
+	 * Applies an AND operation to all the given {@link Specification}s.
+	 *
+	 * @param specifications The {@link Specification}s to compose. Can contain {@code null}s.
+	 * @return The conjunction of the specifications
+	 * @see #and(Specification)
+	 */
+	static <T> Specification<T> allOf(Iterable<Specification<T>> specifications) {
+
+		return StreamSupport.stream(specifications.spliterator(), false) //
+				.reduce(Specification.where(null), Specification::and);
+	}
+
+	/**
+	 * @see #allOf(Iterable)
+	 */
+	@SafeVarargs
+	static <T> Specification<T> allOf(Specification<T>... specifications) {
+		return allOf(Arrays.asList(specifications));
+	}
+
+	/**
+	 * Applies an OR operation to all the given {@link Specification}s.
+	 *
+	 * @param specifications The {@link Specification}s to compose. Can contain {@code null}s.
+	 * @return The disjunction of the specifications
+	 * @see #or(Specification)
+	 */
+	static <T> Specification<T> anyOf(Iterable<Specification<T>> specifications) {
+
+		return StreamSupport.stream(specifications.spliterator(), false) //
+				.reduce(Specification.where(null), Specification::or);
+	}
+
+	/**
+	 * @see #anyOf(Iterable)
+	 */
+	@SafeVarargs
+	static <T> Specification<T> anyOf(Specification<T>... specifications) {
+		return anyOf(Arrays.asList(specifications));
+	}
 }

spring-data-jpa/src/test/java/org/springframework/data/jpa/domain/SpecificationUnitTests.java

@@ -44,6 +44,7 @@
  * @author Sebastian Staudt
  * @author Jens Schauder
  * @author Mark Paluch
+ * @author Daniel Shuy
  */
 @SuppressWarnings("serial")
 @ExtendWith(MockitoExtension.class)
@@ -118,6 +119,42 @@ void orConcatenatesNullSpecToSpec() {
 		assertThat(specification.toPredicate(root, query, builder)).isEqualTo(predicate);
 	}
 
+	@Test // DATAJPA-1651
+	public void allOfConcatenatesNull() {
+
+		Specification<Object> specification = Specification.allOf(null, spec, null);
+
+		assertThat(specification).isNotNull();
+		assertThat(specification.toPredicate(root, query, builder)).isEqualTo(predicate);
+	}
+
+	@Test // DATAJPA-1651
+	public void anyOfConcatenatesNull() {
+
+		Specification<Object> specification = Specification.anyOf(null, spec, null);
+
+		assertThat(specification).isNotNull();
+		assertThat(specification.toPredicate(root, query, builder)).isEqualTo(predicate);
+	}
+
+	@Test // DATAJPA-1651
+	public void emptyAllOfReturnsEmptySpecification() {
+
+		Specification<Object> specification = Specification.allOf();
+
+		assertThat(specification).isNotNull();
+		assertThat(specification.toPredicate(root, query, builder)).isNull();
+	}
+
+	@Test // DATAJPA-1651
+	public void emptyAnyOfReturnsEmptySpecification() {
+
+		Specification<Object> specification = Specification.anyOf();
+
+		assertThat(specification).isNotNull();
+		assertThat(specification.toPredicate(root, query, builder)).isNull();
+	}
+
 	@Test // DATAJPA-523
 	void specificationsShouldBeSerializable() {
 

spring-data-jpa/src/test/java/org/springframework/data/jpa/repository/UserRepositoryTests.java

@@ -94,6 +94,7 @@
  * @author Jesse Wouters
  * @author Greg Turnquist
  * @author Diego Krupitza
+ * @author Daniel Shuy
  */
 @ExtendWith(SpringExtension.class)
 @ContextConfiguration("classpath:application-context.xml")
@@ -489,12 +490,21 @@ void throwsExceptionForUnderSpecifiedSingleEntitySpecification() {
 				.isThrownBy(() -> repository.findOne(userHasFirstnameLike("e")));
 	}
 
-	@Test
+	@Test // DATAJPA-1651
 	void executesCombinedSpecificationsCorrectly() {
 
 		flushTestUsers();
-		Specification<User> spec = userHasFirstname("Oliver").or(userHasLastname("Arrasz"));
-		assertThat(repository.findAll(spec)).hasSize(2);
+		Specification<User> spec1 = userHasFirstname("Oliver").or(userHasLastname("Arrasz"));
+		List<User> users1 = repository.findAll(spec1);
+		assertThat(users1).hasSize(2);
+
+		Specification<User> spec2 = Specification.anyOf( //
+				userHasFirstname("Oliver"), //
+				userHasLastname("Arrasz"));
+		List<User> users2 = repository.findAll(spec2);
+		assertThat(users2).hasSize(2);
+
+		assertThat(users1).containsExactlyInAnyOrderElementsOf(users2);
 	}
 
 	@Test // DATAJPA-253
@@ -506,16 +516,27 @@ void executesNegatingSpecificationCorrectly() {
 		assertThat(repository.findAll(spec)).containsOnly(secondUser);
 	}
 
-	@Test
+	@Test // DATAJPA-1651
 	void executesCombinedSpecificationsWithPageableCorrectly() {
 
 		flushTestUsers();
-		Specification<User> spec = userHasFirstname("Oliver").or(userHasLastname("Arrasz"));
+		Specification<User> spec1 = userHasFirstname("Oliver").or(userHasLastname("Arrasz"));
 
-		Page<User> users = repository.findAll(spec, PageRequest.of(0, 1));
-		assertThat(users.getSize()).isEqualTo(1);
-		assertThat(users.hasPrevious()).isFalse();
-		assertThat(users.getTotalElements()).isEqualTo(2L);
+		Page<User> users1 = repository.findAll(spec1, PageRequest.of(0, 1));
+		assertThat(users1.getSize()).isEqualTo(1);
+		assertThat(users1.hasPrevious()).isFalse();
+		assertThat(users1.getTotalElements()).isEqualTo(2L);
+
+		Specification<User> spec2 = Specification.anyOf( //
+				userHasFirstname("Oliver"), //
+				userHasLastname("Arrasz"));
+
+		Page<User> users2 = repository.findAll(spec2, PageRequest.of(0, 1));
+		assertThat(users2.getSize()).isEqualTo(1);
+		assertThat(users2.hasPrevious()).isFalse();
+		assertThat(users2.getTotalElements()).isEqualTo(2L);
+
+		assertThat(users1).containsExactlyInAnyOrderElementsOf(users2);
 	}
 
 	@Test
@@ -602,22 +623,22 @@ void removeDetachedObject() {
 		assertThat(repository.count()).isEqualTo(3L);
 	}
 
-	@Test
+	@Test // DATAJPA-1651
 	void executesPagedSpecificationsCorrectly() {
 
 		Page<User> result = executeSpecWithSort(Sort.unsorted());
 		assertThat(result.getContent()).isSubsetOf(firstUser, thirdUser);
 	}
 
-	@Test
+	@Test // DATAJPA-1651
 	void executesPagedSpecificationsWithSortCorrectly() {
 
 		Page<User> result = executeSpecWithSort(Sort.by(Direction.ASC, "lastname"));
 
 		assertThat(result.getContent()).contains(firstUser).doesNotContain(secondUser, thirdUser);
 	}
 
-	@Test
+	@Test // DATAJPA-1651
 	void executesPagedSpecificationWithSortCorrectly2() {
 
 		Page<User> result = executeSpecWithSort(Sort.by(Direction.DESC, "lastname"));
@@ -2821,11 +2842,21 @@ private Page<User> executeSpecWithSort(Sort sort) {
 
 		flushTestUsers();
 
-		Specification<User> spec = userHasFirstname("Oliver").or(userHasLastname("Matthews"));
+		Specification<User> spec1 = userHasFirstname("Oliver").or(userHasLastname("Matthews"));
 
-		Page<User> result = repository.findAll(spec, PageRequest.of(0, 1, sort));
-		assertThat(result.getTotalElements()).isEqualTo(2L);
-		return result;
+		Page<User> result1 = repository.findAll(spec1, PageRequest.of(0, 1, sort));
+		assertThat(result1.getTotalElements()).isEqualTo(2L);
+
+		Specification<User> spec2 = Specification.anyOf( //
+				userHasFirstname("Oliver"), //
+				userHasLastname("Matthews"));
+
+		Page<User> result2 = repository.findAll(spec2, PageRequest.of(0, 1, sort));
+		assertThat(result2.getTotalElements()).isEqualTo(2L);
+
+		assertThat(result1).containsExactlyElementsOf(result2);
+
+		return result2;
 	}
 
 	private interface UserProjectionInterfaceBased {