How can I use another mapping from different class in mapstruct

Question

I would like to mapping a model object to dto model. I already have mapper for one of the object. How can I reuse this mapper in another mapper which is in another class?

I have below as model

    @Getter
    @AllArgsConstructor
    @ToString
    public class History {

      @JsonProperty("identifier")
      private final Identifier identifier;

    @JsonProperty("submitTime")
    private final ZonedDateTime submitTime;

    @JsonProperty("method")
    private final String method;

    @JsonProperty("reason")
    private final String reason;

    @JsonProperty("dataList")
    private final List<Data> dataList;
   }

     @DynamoDBTable(tableName = "history")
     @Data
     @NoArgsConstructor
     public class HistoryDynamo {
        @DynamoDBRangeKey(attributeName = "submitTime")
        @DynamoDBTypeConverted(converter = ZonedDateTimeType.Converter.class)
        private ZonedDateTime submitTime;

        @DynamoDBAttribute(attributeName = "identifier")
        @NonNull
        private Identifier identifier;

        @DynamoDBAttribute(attributeName = "method")
        private String method;

         @DynamoDBAttribute(attributeName = "reason")
         private String reason;

         @DynamoDBAttribute(attributeName = "dataList")
         private List<Data> dataList;
     }

        @Data
        @DynamoDBDocument
        @NoArgsConstructor
        public class Identifier implements Serializable {
    
            @DynamoDBAttribute(attributeName = "number")
            private String number;
    
        @DynamoDBAttribute(attributeName = "cityCode")
        @NonNull
        private String cityCode;
    
        @DynamoDBAttribute(attributeName = "countryCode")
        @NonNull
        private String countryCode;
    
        @DynamoDBTypeConverted(converter = LocalDateType.Converter.class)
        private LocalDate mydate;
    }
    
         @Data
         @EqualsAndHashCode
         @NoArgsConstructor
         @RequiredArgsConstructor
         @JsonInclude(JsonInclude.Include.NON_NULL)
         public class Identifier implements Serializable {
    
        @NonNull
        @lombok.NonNull
        @NotNull
        private String number;
    
        @NonNull
        @lombok.NonNull
        @NotNull
        private City city;
    
        @NonNull
        @lombok.NonNull
        @NotNull
        private Country country;
    
        @JsonDeserialize(using = LocalDateDeserializer.class)
        @JsonFormat(shape = JsonFormat.Shape.STRING, pattern = "yyyy-MM-dd'Z'")
        @DateTimeFormat(pattern = "yyyy-MM-dd'Z'")
        @NonNull
        @lombok.NonNull
        @NotNull
        private LocalDate mydate;
    }

And here is my mapping

    @Mapper(componentModel = "spring", unmappedTargetPolicy = ReportingPolicy.WARN, injectionStrategy = InjectionStrategy.CONSTRUCTOR, nullValueMappingStrategy = NullValueMappingStrategy.RETURN_NULL)
    public interface IdentifierMapper {
    
        IdentifierMapper MAPPER = Mappers.getMapper(IdentifierMapper.class);
    
    
        @Mappings({@Mapping(source = "identifier.number", target = "number"),
                   @Mapping(source = "identifier.city.code", target = "cityCode"),
                   @Mapping(source = "identifier.country.code", target = "countryCode"),
                   @Mapping(source = "identifier.mydate", target = "mydate")})
        @Named("toIdentifierDynamo")
        myproject.entity.dynamo.Identifier toIdentifierDynamo(myproject.model.Identifier identifier);
    }
    
    @Mapper(componentModel = "spring", unmappedTargetPolicy = ReportingPolicy.WARN, injectionStrategy = InjectionStrategy.CONSTRUCTOR,
            nullValueMappingStrategy = NullValueMappingStrategy.RETURN_NULL, uses = {IdentifierMapper.class})
    public interface HistoryMapper {
    
        HistoryMapper MAPPER = Mappers.getMapper(HistoryMapper.class);
    
        @Mappings({@Mapping(source = "identifier", target = "identifier", qualifiedByName = "toIdentifierDynamo"),
                  @Mapping(source = "method", target = "method"),
                  @Mapping(source = "reason", target = "reason"),
                  @Mapping(source = "timestamp", target = "timestamp")})
        HistoryDynamo toHistoryDynamo(History history);
    }

I would like to map History to HistoryDynamo and reuse IdentifierMapper to map one of the object in HistoryDynamo. How can I use toIdentifierDynamo in toHistoryDynamo?

Almazan

Which version of lombok and mapstruct are you using? – Caron

mapstruct 1.3.0.Final lombok 1.18.8 – Almazan

It looks like there's a mistake in your class HistoryDynamo... the attribute identifier precedes its type, which is HistoryDynamo instead of... myproject.entity.dynamo.Identifier? – Caron

Thanks. It was a typo. I have fixed the question – Almazan

Answer 1

• First of all you don't have to create instance in Spring. You could just Autowire your Mapper.
• Second of all you don't have to provide @Mapping annotation for each field if it has the same name. Mapstruct will do it for you.
• Your issue could be done using uses parameter of MapStruct mapper HistoryMapper could have in @Mapper annotation parameter uses = IdentifierMapper.class. It will autowire IdentifierMapper into HistoryMapper. By default it will do via field. You could change it also in parameters: injectionStrategy = InjectionStrategy.CONSTRUCTOR and probably it will be enough as you have the same name of field (identifier) and MapStruct should realize that should be use IdentifierMapper

Remediable

Could you add some code examples here to make this answer clearer? – Besot

Hmm, I am trying to implement the as stated above and in my implementation. I do see the mapper being created in the implementation on the main mapper but it lacks the Autowired annotation. Am I missing something how to get that annotation on the implementation mapper becuase it is causing NPE in the tests – Dawdle

Answer 2

Using spring dependency can be injected easily as

private final HistoryMapper 
 historyMapper;

Also for fields with same name in target and source no need to use @Mapping, so in above case below mapper definition is enough to acheive desired result.

@Mapper(
    componentModel = "spring",
    injectionStrategy = InjectionStrategy.CONSTRUCTOR,
    uses = {IdentifierMapper.class})
public interface HistoryMapper {

  HistoryDynamo toHistoryDynamo(History history);

} 

Refer github sample here https://github.com/rakesh-singh-samples/map-struct-samples/tree/stack-question-60523230/src/sample/mapstruct/mapper

Guide

I tried the above example in my code but got an error when trying to run the app: HistoryMapperImpl required a bean of type 'IdentifierMapper' that could not be found. Am I missing something? – Slivovitz

Ok I got it, my IdentifierMapper was missing the @Mapper(componentModel = "spring") configuration. – Slivovitz