Spring data r2dbc and pagination

Question

I'm using the new spring data r2dbc module and i'm able to extract the data using a ReactiveCrudRepository. Now i need to introduce pagination but i cannot manage to do it. I tried with this

public interface TestRepository extends ReactiveCrudRepository<MyEntity, Long> {
    Flux<MyEntity> findByEntityId(Long entityId, Pageable page);
}

but when i try to execute this i obtain this error

org.springframework.data.repository.query.ParameterOutOfBoundsException: Invalid parameter index! You seem to have declared too little query method parameters!
    at org.springframework.data.repository.query.Parameters.getParameter(Parameters.java:237)
    Suppressed: reactor.core.publisher.FluxOnAssembly$OnAssemblyException:

is there a way to use pagination with this module?

Hantsy · Answer 1 · 2020-09-09T04:04:15.570

13

The new R2dbcEntityTemplate Spring Data R2dbc 1.2 contains pagination operations like this.

 private final R2dbcEntityTemplate template;

    public Flux<Post> findByTitleContains(String name) {
        return this.template.select(Post.class)
                .matching(Query.query(where("title").like("%" + name + "%")).limit(10).offset(0))
                .all();
    }

Spring Data R2dbc 1.2 (not released yet) will accept a Pageable parameter as in Repository.

 public Flux<PostSummary> findByTitleLike(String title, Pageable pageable);

The complete code examples, check here, test codes.

edited Sep 09 '20 at 04:04

answered Sep 08 '20 at 04:16

Hantsy

8,006
7
64
109

1

using Pageable in a ReactiveCrudRepository should also work with 1.1.4. – Chris Oct 15 '20 at 09:07

score 4 · Answer 2 · answered Nov 20 '19 at 08:46

No, there currently is no way to use implicit pagination. You should specify your whole queries to use it.

Here is an example:

@Query("SELECT * FROM my_entity WHERE entity_id = :entityId OFFSET :offset LIMIT :limit")
Flux<MyEntity> findByEntityId(Long entityId, int offset, int limit);

score 2 · Answer 3 · answered Apr 15 '21 at 12:42

The newer versions of Spring Data R2dbc accepts Pageable as @Hantsy mentioned, but there is a catch.

If you are fetching all the records without any WHERE clause then following is NOT working:

public interface MyEntityRepository extends ReactiveCrudRepository<MyEntity, Long> {
    Flux<MyEntity> findAll(Pageable pageable);
}

Changing findAll() to findBy() is working fine.

public interface MyEntityRepository extends ReactiveCrudRepository<MyEntity, Long> {
    Flux<MyEntity> findBy(Pageable pageable);
}

David Keating · Answer 4 · 2021-04-13T07:51:56.847

I was able to achieve this using spring-boot-starter-data-r2dbc.2.4.3

As @Hantsy said the ReactiveCrudRepository will accept Pageable as a parameter inside of the queries but this won't solve the paging issue. In hibernate you expect to be returned a Page of an Object but for Reactive it's going to be a Flux.

I was however able to achieve this by using the PageImpl class and using the count method from the ReactiveCrudRepository interface.

For example

public interface TestRepository extends ReactiveCrudRepository<MyEntity, Long> {
    Flux<MyEntity> findByEntityId(Long entityId, Pageable page);
}

public Mono<<Page<MyEntity>> getMyEntities(Long entityId, PageRequest request) {
    return testRepository.findByEntityId(entityId, request)
            .collectList()
            .zipWith(testRepository.count())
            .flatMap(entityTuples -> 
                new PageImpl<>(entityTuples.getT1(), request, entityTuples.getT2()));
}

Spring data r2dbc and pagination

4 Answers4

Linked