Spring webflux convert Entity class to Mono DTO object

Question

First of all ,i am new to spring webflux and trying to do a POC on setting up a reactive spring boot project.i have a use case, where i need to convert the retrieved entity class(PartyDTO) to Mono object(Person : which is a third party business object without constructors and i cant modify it).i googled but unable to find an answer that match my use case.

3rd party object:

  public class Person {
        // no constructors 
        private Integer custId;
        private String fullname;
        private LocalDate date;
        //
        getters and setters
    }

my classes are as follows:

@Table("party")
public class PartyDTO {

    @Id
    private Integer party_id;
    private String name;
    private LocalDate start_date;
}

Service class that calls my repository.

 @Service
     public class ServiceImpl{

     @Override
        public Mono<Person> getParty(String partyId) {
            return 
    partyRepository.findById(Integer.parseInt(partyId)).flatMap(//mapper to convert PartyDTO to Person goes here);
        }
}

i tried to use a flatmap with my custom mapper as shown above, but its not working.Can some one advice me how this can be achieved in a non blocking way(3rd party bean mappers are also fine if it support non blocking approach)

Answer 1

Assuming partyRepository.findById() returns a Mono , you can simply do

    @Service
         public class ServiceImpl{
    
         @Override
            public Mono<Person> getParty(String partyId) {
                 
       return partyRepository.findById(Integer.parseInt(partyId)).map(partyDto->{
         Person person = new Person();
         person.setName(partyDto.getName());
         return Mono.just(person);
});
            }
    }

You can refer to https://projectreactor.io/docs/core/release/api/reactor/core/publisher/Mono.html#just-T-