Mapstruct如何初始化字段

Question

我有一个这样的 DTO

@Data
public class MessageDTO implements Serializable {
    private Long id;
}

和一个实体

@Entity
@Data
public class Message implements Serializable {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id")
    private Long id;

    @Column(name = "timestamp")
    private Instant timestamp;
}

我想创建一个映射器来将 DTO 映射到实体。如何使字段 private Instant timestamp; 具有类似于 Instant.now()?

的值

到目前为止我的映射器

@Mapper(componentModel = "spring", imports = Instant.class)
public interface MessageMapper extends EntityMapper<MessageDTO, Message> {
    @Override
    @Mapping(target = "timestamp", source = "" ,defaultExpression = "java(Instant.now())")
    Message toEntity(MessageDTO dto);
}

编译错误

Compilation failure
[ERROR] /D:/Shared/projects/IdeaProjects/medical/src/main/java/io/medical/service/mapper/MessageMapper.java:[22,45] No property named "" exists in source parameter(s)

Answer 1

问题是由于 source 为空。删除 source 并使用 expression 而不是 defaultExpression。

@Mapper(componentModel = "spring")
public interface MessageMapper extends EntityMapper<MessageDTO, Message> {
    @Override
    @Mapping(target = "timestamp", expression = "java(Instant.now())")
    Message toEntity(MessageDTO dto);
}

当有源但解析时源为空时，defaultExpression 可以方便地为目标赋值。

Mapstruct如何初始化字段

Mapstruct how to initialize fields

java

spring

spring-boot

mapstruct