使用 org.mapstruct 框架的一对多关系映射

Question

如何使用 org.mapstruct 框架映射一对多关系？

DTO 类:

@Data
public class ScheduledJobDTO {

    private String jobName;
    private String jobGroup;
    private String jobClass;
    private String cronExpression;
    private Boolean cronJob;
    private Long repeatTime;
    private Integer repeatCount;
    private Set<ScheduledJobParamsDTO> paramtersDTOs;

}

@Data
@EqualsAndHashCode
public class ScheduledJobParamsDTO {

    String name;
    String value;
}

域 Classes -

@Data
@Entity
@Table(name = "scheduled_job")
public class ScheduledJob {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    @Column(name = "job_name")
    private String jobName;
    @Column(name = "job_group")
    private String jobGroup;
    @Column(name = "job_class")
    private String jobClass;
    @Column(name = "cron_expression")
    private String cronExpression;
    @Column(name = "is_cron_job")
    private Boolean cronJob;
    @Column(name = "repeat_time")
    private Long repeatTime;
    @Column(name = "repeat_count")
    private Integer repeatCount;
    @Column(name = "trigger_start_date")
    private LocalDate triggerStartDate;
    @Column(name = "trigger_end_date")
    private LocalDate triggerEndDate;
    @Column(name = "created_at")
    private LocalDate createdAt;
    @Column(name = "modified_at")
    private LocalDate modifiedAt;
    @Column(name = "is_active")
    private Boolean active;
    @OneToMany(mappedBy = "scheduledJob")
    private Set<ScheduledJobParams> parameters;

}

@Data
@Entity
@Table(name = "scheduled_job_params")
@EqualsAndHashCode
public class ScheduledJobParams {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    Long id;
    @ManyToOne(fetch = FetchType.LAZY, optional = false)
    @JoinColumn(name = "scheduled_job_id", nullable = false)
    ScheduledJob scheduledJob;
    String name;
    String value;
}

映射器Class-

@Mapping(source = ".", target = ".")
@Mapping(source = "paramtersDTOs", target = "parameters")
ScheduledJob mapToDomain(ScheduledJobDTO scheduledJobDTO);

现在，上面的映射器正在映射 ScheduledJob 和 ScheduledJobParams，但是 ScheduledJobParams 引用了 ScheduledJob。

如何将引用 ScheduledJob 映射到 ScheduledJobParams？

Answer 1

您可以通过 @AfterMapping 和 @MappedTarget 来实现。这在参考文档中有描述：12.2. Mapping customization with before-mapping and after-mapping methods.

// Java 8+ otherwise you need to use an abstract class and a for-loop instead
@Mapper(componentModel = "spring")
public interface ScheduledJobMapper {

    @Mapping(target = "parameters", source = "paramtersDTOs")
    ScheduledJob mapToDomain(ScheduledJobDTO dto);

    @AfterMapping
    default void after(@MappingTarget ScheduledJob domain, ScheduledJobDTO dto) {
        domain.getParameters().forEach(scheduledJobParams -> {
            scheduledJobParams.setScheduledJob(domain);
        });
    }
}

但是，当您从 DTO 映射回 entity 时，我相信您不需要填充双向关系（这就是我对 “域” 的理解）。请注意，如果处理不当，打印或序列化此类对象即 JSON 或 XML 会抛出 java.lang.WhosebugError。

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