spring cassandra数据版本2.1.4分页

Question

根据文档：https://docs.spring.io/spring-data/cassandra/docs/2.1.4.RELEASE/reference/html/#repositories.limit-query-result

Spring cassandra 数据使得获取分页信息变得容易。 但是我无法让它工作。

回购、调用和错误：

1.反应呼叫

回购:

public interface MyRepository extends ReactiveCassandraRepository<MyClass, String> {
  @Query("select * from my_keyspace.my_table where solr_query = ?0")
  Mono<Slice<MyClass>> findMono(String solrQuery, Pageable page);
}

通话：

 Mono<Slice<MyClass>>  repository.findMono(queryString, CassandraPageRequest.first(20));

错误：

"exceptionDescription":"org.springframework.core.codec.CodecException: Type definition error: [simple type, class com.datastax.driver.core.PagingState]; nested exception is com.fasterxml.jackson.databind.exc.InvalidDefinitionException: No serializer found for class com.datastax.driver.core.PagingState and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS) (through reference chain: org.springframework.data.domain.SliceImpl[\"pageable\"]->org.springframework.data.cassandra.core.query.CassandraPageRequest[\"pagingState\"])","lines":["org.springframework.http.codec.json.AbstractJackson2Encoder.encodeValue(AbstractJackson2Encoder.java:175)","org.springframework.http.codec.json.AbstractJackson2Encoder.lambda$encode[=18=](AbstractJackson2Encoder.java:122)","reactor.core.publisher.FluxMap$MapSubscriber.onNext(FluxMap.java:100)","reactor.core.publisher.FluxSwitchIfEmpty$SwitchIfEmptySubscriber.onNext(FluxSwitchIfEmpty.java:67)","reactor.core.publisher.FluxMap$MapSubscriber.onNext(FluxMap.java:114)","reactor.core.publisher.FluxDefaultIfEmpty$DefaultIfEmptySubscriber.onNext(FluxDefaultIfEmpty.java:92)","reactor.core.publisher.Operators$MonoSubscriber.complete(Operators.java:1476)","reactor.core.publisher.MonoFlatMap$FlatMapInner.onNext(MonoFlatMap.java:241)","reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.onNext(FluxMapFuseable.java:121)","reactor.core.publisher.Operators$MonoSubscriber.complete(Operators.java:1476)","reactor.core.publisher.MonoCollectList$MonoBufferAllSubscriber.onComplete(MonoCollectList.java:118)","reactor.core.publisher.FluxTake$TakeFuseableSubscriber.onComplete(FluxTake.java:424)","reactor.core.publisher.FluxTake$TakeFuseableSubscriber.onNext(FluxTake.java:404)","reactor.core.publisher.FluxIterable$IterableSubscription.fastPath(FluxIterable.java:311)","reactor.core.publisher.FluxIterable$IterableSubscription.request(FluxIterable.java:198)"],

2。与 ReactiveSortingRepository 反应

回购：

public interface LocationRepository extends ReactiveSortingRepository<MyClass, String> {
}

通话：

 repository.findAll(CassandraPageRequest.first(20))

错误：

Syntax error: findAll can't be applied to CassandraPageRequest.

3。简单调用获取页面。

回购：

public interface MyRepository extends CassandraRepository<MyClass, MyClassKey> {
Page<MyClass> findByKeyTerminalIdAndSolrQuery(String solrQuery, Pageable page);
}

启动时出错：

Caused by: org.springframework.dao.InvalidDataAccessApiUsageException: Page queries are not supported. Use a Slice query.

4。使用 PagingAndSortingRepository

回购：

public interface MyRepository extends PagingAndSortingRepository<MyClass, MyClassKey> {

}

通话：

   Page<Vessel> vessels = repository.findAll(CassandraPageRequest.first(10));

错误：

springframework.data.mapping.PropertyReferenceException: No property findAll found for type MyClass!

Answer 1

欢迎来到 Stack Overflow。

第一个例子是合适的：

public interface MyRepository extends ReactiveCassandraRepository<MyClass, String> {
  @Query("select * from my_keyspace.my_table where solr_query = ?0")
  Mono<Slice<MyClass>> findMono(String solrQuery, Pageable page);
}

Mono<Slice<MyClass>>  repository.findMono(queryString, CassandraPageRequest.first(20));

问题是当您将 SliceImpl（Slice 的实现）传递给 WebFlux 时，Jackson 无法对其进行编码（根据堆栈跟踪）。所以查询产生了正确的结果，但是如果你想 JSON 编码它，你需要传递 Slice 内容，而不是 Slice 本身。

相关说明：ReactiveCassandraRepository 未实现 ReactiveSortingRepository，因为带有 Sort 参数的 Casandra 查询始终需要 WHERE 子句。查看 ReactiveSortingRepository，您会看到一个 findAll(Sort) 方法不采用过滤条件：

public interface ReactiveSortingRepository<T, ID> extends ReactiveCrudRepository<T, ID> {
    Flux<T> findAll(Sort sort);
}