Mapstruct 映射 - 字符串到列表<String>

Question

I am struggling to map a string object from source(Relation.class) and to a List of target(RelationListDTO.class) .

Relation.java

   public class Relation {

    private String name;
    private String email;
    private String completeAddress;

    // getters and setters
}

RelationListDTO.java

public class RelationListDTO {
        private String name;
        private String email;
        private List<Address> address;

        // getters and setters
    }

Address.java

public class Address{
private String street;
private String city;
// getters and setters
}

Mapper class

@Mapper

public interface RelationMapper {

    @Mapping(source = "completeAddress", target = "address.get(0).city")
            RelationListDTO relationToListDto(Relation relation);
} 

But it is not working. Could anyone please help.

Answer 1

What you are trying to do using MapStruct is not possible. Because MapStruct doesn't work with run time objects. MapStruct only generated plain java code for mapping two beans. And I find your requirement is little unique. You have a list of Addresses but want to map only city from source object? You can still do like this

@Mapping( target = "address", source = "completeAddress")
RelationListDTO relationToListDto(Relation relation);

// MapStruct will know to use this method to map between a `String` and `List<Address>`
default List<Address> mapAddress(String relation){
      //create new arraylist
      // create new AddressObject and set completeAddress to address.city
     // add that to list and return list

}

Answer 2

Not sure if this was possible at the time of the accepted answer but I had the same problem as you and ended up doing it this way.

@Mapper(imports = Collections.class)
public interface RelationMapper {
    @Mapping(expression = "java(Collections.singletonList(relation.getCompleteAddress()))", target = "address")
            RelationListDTO relationToListDto(Relation relation);
}