tcollins · May 26, 2025 20:09 · RockyMM · Jan 16, 2025 · Draynam · May 26, 2025
diff --git a/-Spring-JPA-Dynamic-Query-With-Limit b/-Spring-JPA-Dynamic-Query-With-Limit
 If you use the findAll(Specification, Pageable) method, a count query is first executed and then the 
 data query is executed if the count returns a value greater than the offset.

 For what I was doing I did not need pageable, but simply wanted to limit my results.  This is easy 
 to do with static named queries and methodNameMagicGoodness queries, but from my research (googling 
 for a few hours) I couldn't find a way to do it with dynamic criteria queries using Specifications.

 During my search I found two things that helped me to figure out how to just do it myself.

 1.) A stackoverflow question.
 How to disable count when Specification and Pageable are used together?
 http://stackoverflow.com/questions/26738199/how-to-disable-count-when-specification-and-pageable-are-used-together
 (where I will add a link to this gist)

 2.) Spring documentation - Adding custom behavior to all repositories
 http://docs.spring.io/spring-data/data-jpa/docs/current/reference/html/#repositories.custom-behaviour-for-all-repositories

 I followed the Spring documentation pretty closely and got this all working pretty quickly without 
 any real problems.
diff --git a/BaseRepository.java b/BaseRepository.java
 @NoRepositoryBean
 public interface BaseRepository<T, ID extends Serializable> extends JpaRepository<T, ID> {
 	List<T> findAll(Specification<T> spec, int offset, int maxResults, Sort sort);
 	List<T> findAll(Specification<T> spec, int offset, int maxResults);
 }
diff --git a/BaseRepositoryFactoryBean.java b/BaseRepositoryFactoryBean.java
 public class BaseRepositoryFactoryBean<R extends JpaRepository<T, I>, T, I extends Serializable> extends JpaRepositoryFactoryBean<R, T, I> {

 	@SuppressWarnings("rawtypes")
 	@Override
 	protected RepositoryFactorySupport createRepositoryFactory(EntityManager entityManager) {
 		return new BaseRepositoryFactory(entityManager);
 	}

 	private static class BaseRepositoryFactory<T, I extends Serializable> extends JpaRepositoryFactory {

 		private final EntityManager em;

 		public BaseRepositoryFactory(EntityManager em) {

 			super(em);
 			this.em = em;
 		}

 		@SuppressWarnings({ "unchecked", "rawtypes", "hiding" })
 		protected <T, ID extends Serializable> SimpleJpaRepository<?, ?> getTargetRepository(RepositoryMetadata metadata, EntityManager entityManager) {
 			SimpleJpaRepository<?, ?> repo = new BaseRepositoryImpl(metadata.getDomainType(), entityManager);
 			return repo;
 		}

 		protected Class<?> getRepositoryBaseClass(RepositoryMetadata metadata) {
 			return BaseRepositoryImpl.class;
 		}
 	}

 }
diff --git a/BaseRepositoryImpl.java b/BaseRepositoryImpl.java
 public class BaseRepositoryImpl<T, ID extends Serializable> extends SimpleJpaRepository<T, ID> implements BaseRepository<T, ID> {

 	private final EntityManager entityManager;

 	public BaseRepositoryImpl(Class<T> domainClass, EntityManager entityManager) {
 		super(domainClass, entityManager);
 		this.entityManager = entityManager;
 	}

 	public List<T> findAll(Specification<T> spec, int offset, int maxResults) {
 		return findAll(spec, offset, maxResults, null);
 	}

 	public List<T> findAll(Specification<T> spec, int offset, int maxResults, Sort sort) {
 		TypedQuery<T> query = getQuery(spec, sort);

 		if (offset < 0) {
 			throw new IllegalArgumentException("Offset must not be less than zero!");
 		}
 		if (maxResults < 1) {
 			throw new IllegalArgumentException("Max results must not be less than one!");
 		}

 		query.setFirstResult(offset);
 		query.setMaxResults(maxResults);
 		return query.getResultList();
 	}

 }
diff --git a/MySpringBootApplication.java b/MySpringBootApplication.java
 @SpringBootApplication
 @EnableJpaRepositories(repositoryFactoryBeanClass = BaseRepositoryFactoryBean.class)
 public class MySpringBootApplication {

 	public static void main(String[] args) {
 		SpringApplication app = new SpringApplication(MySpringBootApplication.class);
 		app.run(args);
 	}

 }
diff --git a/UserRepository.java b/UserRepository.java
 // This is just to show an example of a repo
 public interface UserRepository extends BaseRepository<User, Long>, JpaSpecificationExecutor<User> {
 	
 }
	If you use the findAll(Specification, Pageable) method, a count query is first executed and then the
	data query is executed if the count returns a value greater than the offset.

	For what I was doing I did not need pageable, but simply wanted to limit my results. This is easy
	to do with static named queries and methodNameMagicGoodness queries, but from my research (googling
	for a few hours) I couldn't find a way to do it with dynamic criteria queries using Specifications.

	During my search I found two things that helped me to figure out how to just do it myself.

	1.) A stackoverflow question.
	How to disable count when Specification and Pageable are used together?
	http://stackoverflow.com/questions/26738199/how-to-disable-count-when-specification-and-pageable-are-used-together
	(where I will add a link to this gist)

	2.) Spring documentation - Adding custom behavior to all repositories
	http://docs.spring.io/spring-data/data-jpa/docs/current/reference/html/#repositories.custom-behaviour-for-all-repositories

	I followed the Spring documentation pretty closely and got this all working pretty quickly without
	any real problems.
	@NoRepositoryBean
	public interface BaseRepository<T, ID extends Serializable> extends JpaRepository<T, ID> {
	List<T> findAll(Specification<T> spec, int offset, int maxResults, Sort sort);
	List<T> findAll(Specification<T> spec, int offset, int maxResults);
	}
	public class BaseRepositoryFactoryBean<R extends JpaRepository<T, I>, T, I extends Serializable> extends JpaRepositoryFactoryBean<R, T, I> {

	@SuppressWarnings("rawtypes")
	@Override
	protected RepositoryFactorySupport createRepositoryFactory(EntityManager entityManager) {
	return new BaseRepositoryFactory(entityManager);
	}

	private static class BaseRepositoryFactory<T, I extends Serializable> extends JpaRepositoryFactory {

	private final EntityManager em;

	public BaseRepositoryFactory(EntityManager em) {

	super(em);
	this.em = em;
	}

	@SuppressWarnings({ "unchecked", "rawtypes", "hiding" })
	protected <T, ID extends Serializable> SimpleJpaRepository<?, ?> getTargetRepository(RepositoryMetadata metadata, EntityManager entityManager) {
	SimpleJpaRepository<?, ?> repo = new BaseRepositoryImpl(metadata.getDomainType(), entityManager);
	return repo;
	}

	protected Class<?> getRepositoryBaseClass(RepositoryMetadata metadata) {
	return BaseRepositoryImpl.class;
	}
	}

	}
	public class BaseRepositoryImpl<T, ID extends Serializable> extends SimpleJpaRepository<T, ID> implements BaseRepository<T, ID> {

	private final EntityManager entityManager;

	public BaseRepositoryImpl(Class<T> domainClass, EntityManager entityManager) {
	super(domainClass, entityManager);
	this.entityManager = entityManager;
	}

	public List<T> findAll(Specification<T> spec, int offset, int maxResults) {
	return findAll(spec, offset, maxResults, null);
	}

	public List<T> findAll(Specification<T> spec, int offset, int maxResults, Sort sort) {
	TypedQuery<T> query = getQuery(spec, sort);

	if (offset < 0) {
	throw new IllegalArgumentException("Offset must not be less than zero!");
	}
	if (maxResults < 1) {
	throw new IllegalArgumentException("Max results must not be less than one!");
	}

	query.setFirstResult(offset);
	query.setMaxResults(maxResults);
	return query.getResultList();
	}

	}
	@SpringBootApplication
	@EnableJpaRepositories(repositoryFactoryBeanClass = BaseRepositoryFactoryBean.class)
	public class MySpringBootApplication {

	public static void main(String[] args) {
	SpringApplication app = new SpringApplication(MySpringBootApplication.class);
	app.run(args);
	}

	}
	// This is just to show an example of a repo
	public interface UserRepository extends BaseRepository<User, Long>, JpaSpecificationExecutor<User> {

	}