modelmapperを使用してフィールドをマッピングするときにカスタムロジックを適用する方法

Question

フィールドマッピングにカスタムロジックを適用する方法は？この例では、LocalDate birthdateのうちint ageを計算したいとします。

public class ModelMapperConfigTest { 

    @Data 
    public static class Person { 
     private LocalDate birthdate; 
    } 

    @Data 
    public static class PersonDto { 
     private long age; 
    } 

    // Test data 
    LocalDate birthdate = LocalDate.of(1985, 10, 5); 
    long age = 32; 
    Clock clock = Clock.fixed(birthdate.plusYears(age).atStartOfDay(ZoneId.systemDefault()).toInstant(), ZoneId.systemDefault()); 

    @Test 
    public void should_calc_age() { 

     ModelMapper modelMapper = new ModelMapper(); 
     modelMapper.getConfiguration().setMatchingStrategy(MatchingStrategies.STRICT); 

     // TODO: How to configure the Mapper so that calcBirthdate is used? 

     // test that all fields are mapped 
     modelMapper.validate(); 

     // test that the age is calculated 
     Person person = new Person(); 
     person.setBirthdate(birthdate); 
     PersonDto personDto = modelMapper.map(person, PersonDto.class); 
     assertTrue(personDto.age == age); 
    } 

    // This method should be used for mapping. In real, this could be a service call 
    private long calcBirthdate(LocalDate birthdate) { 
     return YEARS.between(birthdate, LocalDate.now(clock)); 
    } 
} 

Answer 1

これにはConverterを使用できます。あなたのケースではbirthdateからageへのマッピングのためにConverter<LocalDate, Long>を登録してください。

これは、このようなラムダを行うことができます。

@Test 
public void should_calc_age() { 

    ModelMapper modelMapper = new ModelMapper(); 
    modelMapper.getConfiguration().setMatchingStrategy(MatchingStrategies.STRICT); 

    modelMapper.createTypeMap(Person.class, PersonDto.class) 
      .addMappings(mapper -> 
        mapper 
          // This is your converter. 
          // Here you have access to getSource() (birthdate). 
          .using(ctx -> calcBirthdate((LocalDate) ctx.getSource())) 

          // Now define the mapping birthdate to age 
          .map(Person::getBirthdate, PersonDto::setAge)); 

    // test that all fields are mapped 
    modelMapper.validate(); 

    // test that the age is calculated 
    Person person = new Person(); 
    person.setBirthdate(birthdate); 
    PersonDto personDto = modelMapper.map(person, PersonDto.class); 
    assertTrue(personDto.age == age); 
}