Hands-On Microservices with Spring Boot and Spring Cloud

Non-blocking persistence using Spring Data for MongoDB

Making the MongoDB-based repositories for the product and recommendation services reactive is very simple:

• Change to the ReactiveCrudRepository base class for the repositories 
• Change the custom finder methods to return a Mono or Flux object

The ProductRepository and RecommendationRepository look like the following after the change:

public interface ProductRepository extends ReactiveCrudRepository<ProductEntity, String> {    Mono<ProductEntity> findByProductId(int productId);}public interface RecommendationRepository extends ReactiveCrudRepository<RecommendationEntity, String> {    Flux<RecommendationEntity> findByProductId(int productId);}

No changes are applied to the persistence code ...