MapStruct：來自不同實體的字段映射到相同實體的不同字段

Question

我有A，B和C類.A類有三個變量，它根據B類和C類的不同字段填充。當我使用mapper填充對象時，只保留最后使用的映射器值。 如何確保填充所有值。 我使用MapStruct映射器（版本1.2.0）與Spring Boot版本2.0.3

Sample code below:
Class A{

  String a;
  String b;
  String c;

  }

Class B{
 String b1;
}

Class C{
    String c1;
}

public interface AtoCmapper{
  @Mappings({
      @Mapping(target="c", source="source.c1")
  })
  A CtoA(C source);

  @Mappings({
      @Mapping(target="c1", source="source.c")
  })
  C AtoC(A source);
}

public interface AtoBmapper{
  @Mappings({
      @Mapping(target="b", source="source.b1")
  })
  A BtoA(B source);

  @Mappings({
      @Mapping(target="b1", source="source.b")
  })
  B AtoB(A source);
}

Class DAO{

 @Autowired
 AtoBmapper aToBMapper;

 @Autowired
 AtoCmapper aToCMapper;

 public void testMapping(){
  A aObject = new A();

  aObject = aToBMapper(bObject); // Assume bObject is object to Type B and it is initialized properly

  aObject = aToCMapper(cObject); // Assume cObject is object to Type B and it is initialized properly
 }

 //Now when I call testMapping() resulting A object only has value set for variable c, value of b is lost.
 How can I make sure that Values from B and C are set properly to Class A
}

Answer 1

MapStruct可以更新現有實例 ！ 為此，請使用具有類型A的第二個@MappingTarget注釋參數的變體引入新的映射方法（或替換舊映射方法）（在這種情況下，可以用void替換返回類型）：

// In AtoBmapper
@Mappings(...)
void updateAFromB(B source, @MappingTarget A target);

// In AtoCmapper
@Mappings(...)
void updateAFromC(C source, @MappingTarget A target);

然后你可以寫：

A aObject = new A();

aToBMapper.updateAFromB(bObject, aObject);
aToCMapper.updateAFromC(cObject, aObject);

// now aObject should contain the cumulated data from b and c