mappedBy引用了一个未知的目标实体属性。

Question

我正在为使用Hibernate的简单实践应用程序工作。它有简单的映射，例如制造商可以拥有许多手机。但是一部手机只能由单个制造商制造。以下是我认为代码应该是什么。

package mobileconsumers.entity.dto;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.Table;


@Entity
@Table(name="ms_ref_mobile")
public class MobileDTO {

private Long id;
private String model;
private ManufacturerDTO manufacturerDTO;

@Id
@GeneratedValue(strategy=GenerationType.IDENTITY)
@Column(name="MOBILE_ID")
public Long getId() {
    return id;
}
public void setId(Long id) {
    this.id = id;
}
public String getModel() {
    return model;
}
public void setModel(String model) {
    this.model = model;
}
@ManyToOne(fetch=FetchType.LAZY)
@JoinColumn(name="MANUFACTURER_ID")
public ManufacturerDTO getManufacturer() {
    return manufacturerDTO;
}
public void setManufacturer(ManufacturerDTO manufacturer) {
    this.manufacturerDTO = manufacturer;
}


}

这是第二个数据传输对象（DTO）。

package mobileconsumers.entity.dto;

import java.util.HashSet;
import java.util.Set;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.OneToMany;
import javax.persistence.Table;

@Entity
@Table(name="ms_ref_manufacturer")
public class ManufacturerDTO {

private Long id;
private String name;
private Set<MobileDTO> mobileDTOs = new HashSet<>(0);

@Id
@GeneratedValue(strategy=GenerationType.IDENTITY)
@Column(name="MANUFACTURER_ID")
public Long getId() {
    return id;
}
public void setId(Long id) {
    this.id = id;
}
@Column(name="NAME")
public String getName() {
    return name;
}
public void setName(String name) {
    this.name = name;
}
@OneToMany(fetch=FetchType.LAZY,mappedBy="manufacturerDTO")
public Set<MobileDTO> getMobileDTOs() {
    return mobileDTOs;
}
public void setMobileDTOs(Set<MobileDTO> mobileDTOs) {
    this.mobileDTOs = mobileDTOs;
}


}

当我尝试启动服务器时，它会给我一个错误，说..

org.hibernate.AnnotationException：mappedBy参考了未知的目标实体属性：mobileconsumers.entity.dto.MobileDTO.manufacturerDTO在mobileconsumers.entity.dto.ManufacturerDTO.mobileDTOs中

对我来说，映射似乎是没有问题的。一定有些非常愚蠢我遗漏了的东西。只需要一双新鲜的眼睛来查看我的代码，并找出问题所在...

- SandeepKumar

Answer 1

将mappedBy的值更改为引用关联的@ManyToOne端上的manufacturer属性：

@OneToMany(fetch=FetchType.LAZY,mappedBy="manufacturer")
public Set<MobileDTO> getMobileDTOs() {
    return mobileDTOs;
}

- Debojit Saikia

---

是的，那个方法起作用了。下面的答案告诉了我原因。我想我在创建getter和setter时做错了什么。非常感谢您。 - SandeepKumar