Allow Supertypes Specifications in JpaSpecificationExecutor

spring-data-jpa/src/main/java/org/springframework/data/jpa/convert/QueryByExamplePredicateBuilder.java

@@ -93,7 +93,7 @@ public static <T> Predicate getPredicate(Root<T> root, CriteriaBuilder cb, Examp
 	 * @return {@literal null} indicates no constraints
 	 */
 	@Nullable
-	public static <T> Predicate getPredicate(Root<T> root, CriteriaBuilder cb, Example<T> example,
+	public static <T> Predicate getPredicate(Root<? extends T> root, CriteriaBuilder cb, Example<T> example,
 			EscapeCharacter escapeCharacter) {
 
 		Assert.notNull(root, "Root must not be null");

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

@@ -16,7 +16,6 @@
 package org.springframework.data.jpa.domain;
 
 import jakarta.persistence.criteria.CriteriaBuilder;
-import jakarta.persistence.criteria.CriteriaDelete;
 import jakarta.persistence.criteria.CriteriaQuery;
 import jakarta.persistence.criteria.Predicate;
 import jakarta.persistence.criteria.Root;
@@ -77,7 +76,7 @@ static <T> Specification<T> where(@Nullable Specification<T> spec) {
 	 * @return The conjunction of the specifications
 	 * @since 2.0
 	 */
-	default Specification<T> and(@Nullable Specification<T> other) {
+	default <U extends T> Specification<U> and(@Nullable Specification<? super U> other) {
 		return SpecificationComposition.composed(this, other, CriteriaBuilder::and);
 	}
 
@@ -88,7 +87,7 @@ default Specification<T> and(@Nullable Specification<T> other) {
 	 * @return The disjunction of the specifications
 	 * @since 2.0
 	 */
-	default Specification<T> or(@Nullable Specification<T> other) {
+	default <U extends T> Specification<U> or(@Nullable Specification<? super U> other) {
 		return SpecificationComposition.composed(this, other, CriteriaBuilder::or);
 	}
 
@@ -102,7 +101,7 @@ default Specification<T> or(@Nullable Specification<T> other) {
 	 * @return a {@link Predicate}, may be {@literal null}.
 	 */
 	@Nullable
-	Predicate toPredicate(Root<T> root, CriteriaQuery<?> query, CriteriaBuilder criteriaBuilder);
+	Predicate toPredicate(Root<? extends T> root, CriteriaQuery<?> query, CriteriaBuilder criteriaBuilder);
 
 	/**
 	 * Applies an AND operation to all the given {@link Specification}s.

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

@@ -15,13 +15,13 @@
  */
 package org.springframework.data.jpa.domain;
 
-import java.io.Serializable;
-
 import jakarta.persistence.criteria.CriteriaBuilder;
 import jakarta.persistence.criteria.CriteriaQuery;
 import jakarta.persistence.criteria.Predicate;
 import jakarta.persistence.criteria.Root;
 
+import java.io.Serializable;
+
 import org.springframework.lang.Nullable;
 
 /**
@@ -40,7 +40,7 @@ interface Combiner extends Serializable {
 		Predicate combine(CriteriaBuilder builder, @Nullable Predicate lhs, @Nullable Predicate rhs);
 	}
 
-	static <T> Specification<T> composed(@Nullable Specification<T> lhs, @Nullable Specification<T> rhs,
+	static <T> Specification<T> composed(@Nullable Specification<? super T> lhs, @Nullable Specification<? super T> rhs,
 			Combiner combiner) {
 
 		return (root, query, builder) -> {
@@ -57,8 +57,8 @@ static <T> Specification<T> composed(@Nullable Specification<T> lhs, @Nullable S
 	}
 
 	@Nullable
-	private static <T> Predicate toPredicate(@Nullable Specification<T> specification, Root<T> root, CriteriaQuery<?> query,
-			CriteriaBuilder builder) {
+	private static <T> Predicate toPredicate(@Nullable Specification<? super T> specification, Root<? extends T> root,
+			CriteriaQuery<?> query, CriteriaBuilder builder) {
 		return specification == null ? null : specification.toPredicate(root, query, builder);
 	}
 }

spring-data-jpa/src/main/java/org/springframework/data/jpa/repository/JpaSpecificationExecutor.java

@@ -46,15 +46,15 @@ public interface JpaSpecificationExecutor<T> {
 	 * @return never {@literal null}.
 	 * @throws org.springframework.dao.IncorrectResultSizeDataAccessException if more than one entity found.
 	 */
-	Optional<T> findOne(Specification<T> spec);
+	Optional<T> findOne(Specification<? super T> spec);
 
 	/**
 	 * Returns all entities matching the given {@link Specification}.
 	 *
 	 * @param spec must not be {@literal null}.
 	 * @return never {@literal null}.
 	 */
-	List<T> findAll(Specification<T> spec);
+	List<T> findAll(Specification<? super T> spec);
 
 	/**
 	 * Returns a {@link Page} of entities matching the given {@link Specification}.
@@ -63,7 +63,7 @@ public interface JpaSpecificationExecutor<T> {
 	 * @param pageable must not be {@literal null}.
 	 * @return never {@literal null}.
 	 */
-	Page<T> findAll(Specification<T> spec, Pageable pageable);
+	Page<T> findAll(Specification<? super T> spec, Pageable pageable);
 
 	/**
 	 * Returns all entities matching the given {@link Specification} and {@link Sort}.
@@ -72,15 +72,15 @@ public interface JpaSpecificationExecutor<T> {
 	 * @param sort must not be {@literal null}.
 	 * @return never {@literal null}.
 	 */
-	List<T> findAll(Specification<T> spec, Sort sort);
+	List<T> findAll(Specification<? super T> spec, Sort sort);
 
 	/**
 	 * Returns the number of instances that the given {@link Specification} will return.
 	 *
 	 * @param spec the {@link Specification} to count instances for, must not be {@literal null}.
 	 * @return the number of instances.
 	 */
-	long count(Specification<T> spec);
+	long count(Specification<? super T> spec);
 
 	/**
 	 * Checks whether the data store contains elements that match the given {@link Specification}.
@@ -89,7 +89,7 @@ public interface JpaSpecificationExecutor<T> {
 	 * @return {@code true} if the data store contains elements that match the given {@link Specification} otherwise
 	 *         {@code false}.
 	 */
-	boolean exists(Specification<T> spec);
+	boolean exists(Specification<? super T> spec);
 
 	/**
 	 * Deletes by the {@link Specification} and returns the number of rows deleted.
@@ -106,7 +106,7 @@ public interface JpaSpecificationExecutor<T> {
 	 * @return the number of entities deleted.
 	 * @since 3.0
 	 */
-	long delete(Specification<T> spec);
+	long delete(Specification<? super T> spec);
 
 	/**
 	 * Returns entities matching the given {@link Specification} applying the {@code queryFunction} that defines the query
@@ -117,6 +117,7 @@ public interface JpaSpecificationExecutor<T> {
 	 * @return all entities matching the given Example.
 	 * @since 3.0
 	 */
-	<S extends T, R> R findBy(Specification<T> spec, Function<FluentQuery.FetchableFluentQuery<S>, R> queryFunction);
+	<S extends T, R> R findBy(Specification<? super T> spec,
+			Function<FluentQuery.FetchableFluentQuery<S>, R> queryFunction);
 
 }

spring-data-jpa/src/main/java/org/springframework/data/jpa/repository/query/KeysetScrollSpecification.java

@@ -42,7 +42,7 @@
  * @author Christoph Strobl
  * @since 3.1
  */
-public record KeysetScrollSpecification<T> (KeysetScrollPosition position, Sort sort,
+public record KeysetScrollSpecification<T>(KeysetScrollPosition position, Sort sort,
 		JpaEntityInformation<?, ?> entity) implements Specification<T> {
 
 	public KeysetScrollSpecification(KeysetScrollPosition position, Sort sort, JpaEntityInformation<?, ?> entity) {
@@ -84,7 +84,7 @@ public static Sort createSort(KeysetScrollPosition position, Sort sort, JpaEntit
 	}
 
 	@Override
-	public Predicate toPredicate(Root<T> root, CriteriaQuery<?> query, CriteriaBuilder criteriaBuilder) {
+	public Predicate toPredicate(Root<? extends T> root, CriteriaQuery<?> query, CriteriaBuilder criteriaBuilder) {
 		return createPredicate(root, criteriaBuilder);
 	}
 

spring-data-jpa/src/main/java/org/springframework/data/jpa/repository/support/FetchableFluentQueryBySpecification.java

@@ -52,25 +52,25 @@
 class FetchableFluentQueryBySpecification<S, R> extends FluentQuerySupport<S, R>
 		implements FluentQuery.FetchableFluentQuery<R> {
 
-	private final Specification<S> spec;
+	private final Specification<? super S> spec;
 	private final Function<Sort, TypedQuery<S>> finder;
 	private final SpecificationScrollDelegate<S> scroll;
-	private final Function<Specification<S>, Long> countOperation;
-	private final Function<Specification<S>, Boolean> existsOperation;
+	private final Function<Specification<? super S>, Long> countOperation;
+	private final Function<Specification<? super S>, Boolean> existsOperation;
 	private final EntityManager entityManager;
 
-	public FetchableFluentQueryBySpecification(Specification<S> spec, Class<S> entityType,
+	public FetchableFluentQueryBySpecification(Specification<? super S> spec, Class<S> entityType,
 			Function<Sort, TypedQuery<S>> finder, SpecificationScrollDelegate<S> scrollDelegate,
-			Function<Specification<S>, Long> countOperation, Function<Specification<S>, Boolean> existsOperation,
-			EntityManager entityManager) {
+			Function<Specification<? super S>, Long> countOperation,
+			Function<Specification<? super S>, Boolean> existsOperation, EntityManager entityManager) {
 		this(spec, entityType, (Class<R>) entityType, Sort.unsorted(), 0, Collections.emptySet(), finder, scrollDelegate,
 				countOperation, existsOperation, entityManager);
 	}
 
-	private FetchableFluentQueryBySpecification(Specification<S> spec, Class<S> entityType, Class<R> resultType,
+	private FetchableFluentQueryBySpecification(Specification<? super S> spec, Class<S> entityType, Class<R> resultType,
 			Sort sort, int limit, Collection<String> properties, Function<Sort, TypedQuery<S>> finder,
-			SpecificationScrollDelegate<S> scrollDelegate, Function<Specification<S>, Long> countOperation,
-			Function<Specification<S>, Boolean> existsOperation, EntityManager entityManager) {
+			SpecificationScrollDelegate<S> scrollDelegate, Function<Specification<? super S>, Long> countOperation,
+			Function<Specification<? super S>, Boolean> existsOperation, EntityManager entityManager) {
 
 		super(resultType, sort, limit, properties, entityType);
 		this.spec = spec;

spring-data-jpa/src/main/java/org/springframework/data/jpa/repository/support/SimpleJpaRepository.java

@@ -427,7 +427,7 @@ public Page<T> findAll(Pageable pageable) {
 	}
 
 	@Override
-	public Optional<T> findOne(Specification<T> spec) {
+	public Optional<T> findOne(Specification<? super T> spec) {
 
 		try {
 			return Optional.of(getQuery(spec, Sort.unsorted()).setMaxResults(2).getSingleResult());
@@ -437,25 +437,25 @@ public Optional<T> findOne(Specification<T> spec) {
 	}
 
 	@Override
-	public List<T> findAll(Specification<T> spec) {
+	public List<T> findAll(Specification<? super T> spec) {
 		return getQuery(spec, Sort.unsorted()).getResultList();
 	}
 
 	@Override
-	public Page<T> findAll(Specification<T> spec, Pageable pageable) {
+	public Page<T> findAll(Specification<? super T> spec, Pageable pageable) {
 
 		TypedQuery<T> query = getQuery(spec, pageable);
 		return pageable.isUnpaged() ? new PageImpl<>(query.getResultList())
 				: readPage(query, getDomainClass(), pageable, spec);
 	}
 
 	@Override
-	public List<T> findAll(Specification<T> spec, Sort sort) {
+	public List<T> findAll(Specification<? super T> spec, Sort sort) {
 		return getQuery(spec, sort).getResultList();
 	}
 
 	@Override
-	public boolean exists(Specification<T> spec) {
+	public boolean exists(Specification<? super T> spec) {
 
 		CriteriaQuery<Integer> cq = this.entityManager.getCriteriaBuilder() //
 				.createQuery(Integer.class) //
@@ -468,7 +468,7 @@ public boolean exists(Specification<T> spec) {
 	}
 
 	@Override
-	public long delete(Specification<T> spec) {
+	public long delete(Specification<? super T> spec) {
 
 		CriteriaBuilder builder = this.entityManager.getCriteriaBuilder();
 		CriteriaDelete<T> delete = builder.createCriteriaDelete(getDomainClass());
@@ -485,23 +485,23 @@ public long delete(Specification<T> spec) {
 	}
 
 	@Override
-	public <S extends T, R> R findBy(Specification<T> spec, Function<FetchableFluentQuery<S>, R> queryFunction) {
+	public <S extends T, R> R findBy(Specification<? super T> spec, Function<FetchableFluentQuery<S>, R> queryFunction) {
 
 		Assert.notNull(spec, "Specification must not be null");
 		Assert.notNull(queryFunction, "Query function must not be null");
 
 		return doFindBy(spec, getDomainClass(), queryFunction);
 	}
 
-	private <S extends T, R> R doFindBy(Specification<T> spec, Class<T> domainClass,
+	private <S extends T, R> R doFindBy(Specification<? super T> spec, Class<T> domainClass,
 			Function<FetchableFluentQuery<S>, R> queryFunction) {
 
 		Assert.notNull(spec, "Specification must not be null");
 		Assert.notNull(queryFunction, "Query function must not be null");
 
 		ScrollQueryFactory scrollFunction = (sort, scrollPosition) -> {
 
-			Specification<T> specToUse = spec;
+			Specification<? super T> specToUse = spec;
 
 			if (scrollPosition instanceof KeysetScrollPosition keyset) {
 				KeysetScrollSpecification<T> keysetSpec = new KeysetScrollSpecification<>(keyset, sort, entityInformation);
@@ -604,7 +604,7 @@ public long count() {
 	}
 
 	@Override
-	public long count(@Nullable Specification<T> spec) {
+	public long count(@Nullable Specification<? super T> spec) {
 		return executeCountQuery(getCountQuery(spec, getDomainClass()));
 	}
 
@@ -687,7 +687,7 @@ protected Page<T> readPage(TypedQuery<T> query, Pageable pageable, @Nullable Spe
 	 * @param pageable can be {@literal null}.
 	 */
 	protected <S extends T> Page<S> readPage(TypedQuery<S> query, final Class<S> domainClass, Pageable pageable,
-			@Nullable Specification<S> spec) {
+			@Nullable Specification<? super S> spec) {
 
 		if (pageable.isPaged()) {
 			query.setFirstResult(PageableUtils.getOffsetAsInteger(pageable));
@@ -704,7 +704,7 @@ protected <S extends T> Page<S> readPage(TypedQuery<S> query, final Class<S> dom
 	 * @param spec can be {@literal null}.
 	 * @param pageable must not be {@literal null}.
 	 */
-	protected TypedQuery<T> getQuery(@Nullable Specification<T> spec, Pageable pageable) {
+	protected TypedQuery<T> getQuery(@Nullable Specification<? super T> spec, Pageable pageable) {
 
 		Sort sort = pageable.isPaged() ? pageable.getSort() : Sort.unsorted();
 		return getQuery(spec, getDomainClass(), sort);
@@ -717,7 +717,7 @@ protected TypedQuery<T> getQuery(@Nullable Specification<T> spec, Pageable pagea
 	 * @param domainClass must not be {@literal null}.
 	 * @param pageable must not be {@literal null}.
 	 */
-	protected <S extends T> TypedQuery<S> getQuery(@Nullable Specification<S> spec, Class<S> domainClass,
+	protected <S extends T> TypedQuery<S> getQuery(@Nullable Specification<? super S> spec, Class<S> domainClass,
 			Pageable pageable) {
 
 		Sort sort = pageable.isPaged() ? pageable.getSort() : Sort.unsorted();
@@ -730,7 +730,7 @@ protected <S extends T> TypedQuery<S> getQuery(@Nullable Specification<S> spec,
 	 * @param spec can be {@literal null}.
 	 * @param sort must not be {@literal null}.
 	 */
-	protected TypedQuery<T> getQuery(@Nullable Specification<T> spec, Sort sort) {
+	protected TypedQuery<T> getQuery(@Nullable Specification<? super T> spec, Sort sort) {
 		return getQuery(spec, getDomainClass(), sort);
 	}
 
@@ -741,12 +741,13 @@ protected TypedQuery<T> getQuery(@Nullable Specification<T> spec, Sort sort) {
 	 * @param domainClass must not be {@literal null}.
 	 * @param sort must not be {@literal null}.
 	 */
-	protected <S extends T> TypedQuery<S> getQuery(@Nullable Specification<S> spec, Class<S> domainClass, Sort sort) {
+	protected <S extends T> TypedQuery<S> getQuery(@Nullable Specification<? super S> spec, Class<S> domainClass,
+			Sort sort) {
 
 		CriteriaBuilder builder = entityManager.getCriteriaBuilder();
 		CriteriaQuery<S> query = builder.createQuery(domainClass);
 
-		Root<S> root = applySpecificationToCriteria(spec, domainClass, query);
+		Root<? extends S> root = applySpecificationToCriteria(spec, domainClass, query);
 		query.select(root);
 
 		if (sort.isSorted()) {
@@ -773,7 +774,8 @@ protected TypedQuery<Long> getCountQuery(@Nullable Specification<T> spec) {
 	 * @param spec can be {@literal null}.
 	 * @param domainClass must not be {@literal null}.
 	 */
-	protected <S extends T> TypedQuery<Long> getCountQuery(@Nullable Specification<S> spec, Class<S> domainClass) {
+	protected <S extends T> TypedQuery<Long> getCountQuery(@Nullable Specification<? super S> spec,
+			Class<S> domainClass) {
 
 		CriteriaBuilder builder = entityManager.getCriteriaBuilder();
 		CriteriaQuery<Long> query = builder.createQuery(Long.class);
@@ -814,8 +816,8 @@ protected QueryHints getQueryHintsForCount() {
 	 * @param domainClass must not be {@literal null}.
 	 * @param query must not be {@literal null}.
 	 */
-	private <S, U extends T> Root<U> applySpecificationToCriteria(@Nullable Specification<U> spec, Class<U> domainClass,
-			CriteriaQuery<S> query) {
+	private <S, U extends T> Root<U> applySpecificationToCriteria(@Nullable Specification<? super U> spec,
+			Class<U> domainClass, CriteriaQuery<S> query) {
 
 		Assert.notNull(domainClass, "Domain class must not be null");
 		Assert.notNull(query, "CriteriaQuery must not be null");
@@ -942,7 +944,7 @@ private static final class ByIdsSpecification<T> implements Specification<T> {
 		}
 
 		@Override
-		public Predicate toPredicate(Root<T> root, CriteriaQuery<?> query, CriteriaBuilder cb) {
+		public Predicate toPredicate(Root<? extends T> root, CriteriaQuery<?> query, CriteriaBuilder cb) {
 
 			Path<?> path = root.get(entityInformation.getIdAttribute());
 			parameter = (ParameterExpression<Collection<?>>) (ParameterExpression) cb.parameter(Collection.class);
@@ -981,7 +983,7 @@ private static class ExampleSpecification<T> implements Specification<T> {
 		}
 
 		@Override
-		public Predicate toPredicate(Root<T> root, CriteriaQuery<?> query, CriteriaBuilder cb) {
+		public Predicate toPredicate(Root<? extends T> root, CriteriaQuery<?> query, CriteriaBuilder cb) {
 			return QueryByExamplePredicateBuilder.getPredicate(root, cb, example, escapeCharacter);
 		}
 	}

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

@@ -217,7 +217,7 @@ void orCombinesSpecificationsInOrder() {
 	static class SerializableSpecification implements Serializable, Specification<Object> {
 
 		@Override
-		public Predicate toPredicate(Root<Object> root, CriteriaQuery<?> query, CriteriaBuilder cb) {
+		public Predicate toPredicate(Root<?> root, CriteriaQuery<?> query, CriteriaBuilder cb) {
 			return null;
 		}
 	}