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?

Answer 1

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

Answer 2

• 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