Java中的OneToMany

写在开头

使用jhipster声明的OneToMany在One的一方DTO中是没有与Many的DTO的映射关系的, 为了在One的一方DTO中使用Many的DTO, 使用以下三步解决此问题。

步骤

1. OneDTO 中的"mark 1"处为自己写的一对多的关系, 此处变量名称不能与实体One中相应的变量名称一致,否则编译失败。

2. OneMapper 中的"mark 2"处 uses属性添加ManyMapper。

2. OneMapper 中的"mark 3"处使用@Mapping注解声明 Entity 转 DTO 的映射关系。

Entity

@Entity
@Table(name = "one")
public class One {
    ...
    
    @OneToMany(mappedBy = "one")
    private Set<Many> manys = new HashSet<>();
    
    ...
    
    public void setManys(Set<Many> manys) {
        this.manys = manys;
    }
    
    public Set<Many> getManys() {
        return manys;
    }
}

@Entity
@Table(name = "many")
public class Many {
    ...
    
    @ManyToOne
    private One one;
}

DTO

public class OneDTO {
    ...
    
    // mark 1
    private Set<ManyDTO> manyDTOS = new HashSet<>();
    
    ...
    
    public void setManyDTOS(Set<ManyDTO> manyDTOS) {
        this.manyDTOS = manyDTOS;
    }
    
    public Set<ManyDTO> getManyDTOS() {
        return manyDTOS;
    }
}

public class ManyDTO {
    ...
    
    private Long oneId;
    
    ...
    
    public void setOneId(Long oneId) {
        this.oneId = oneId;
    }
    
    public Long getOneId() {
        return oneId;
    }
}

Mapper

// mark 2
@Mapper(componentModel = "spring", uses = {ManyMapper.class})
public interface OneMapper extends EntityMapper<OneDTO, One> {
    
    // mark 3
    @Mapping(souce = "manys", target = "manyDTOS")
    OneDTO toDto(One one);
    
    ...
    
}

@mapper(componentModel = "spring", uses = {OneMapper.class})
public interface ManyMapper extends EntityMapper<ManyDTO, Many>{
    
    ...
    
}