Java :mappedBy 引用一个未知的目标实体属性
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: mappedBy reference an unknown target entity property
提问by SandeepKumar
I am working on a simple practice application for using hibernate. It has simple mapping like a manufacturer can have many mobiles. But a mobile can only be manufactured by single manufacturer. Here is what I think the code should be.
我正在开发一个使用 hibernate 的简单练习应用程序。它具有简单的映射，就像制造商可以拥有许多手机一样。但是手机只能由单一制造商制造。这是我认为的代码应该是什么。
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;
}
}
this is the second dto
这是第二个 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;
}
}
When I try to start my server it gives me an error saying..
org.hibernate.AnnotationException: mappedBy reference anunknown target entity property: mobileconsumers.entity.dto.MobileDTO.manufacturerDTO in mobileconsumers.entity.dto.ManufacturerDTO.mobileDTOsThe mapping seems to be fine to me. there must be something really silly that I am missing out. Just needed fresh pair of eyes to look at my code and figure out whats going wrong..
当我尝试启动我的服务器时，它给了我一个错误说..
org.hibernate.AnnotationException: mappedBy reference anunknown target entity property: mobileconsumers.entity.dto.MobileDTO.manufacturerDTO in mobileconsumers.entity.dto.ManufacturerDTO.mobileDTOs映射对我来说似乎很好。我错过了一些非常愚蠢的东西。只需要一双新的眼睛来看看我的代码并找出出了什么问题..
采纳答案by Debojit Saikia
Change mappedByvalue, so that it refers the manufacturerproperty on the @ManyToOneside of the association:
更改mappedBy值，使其引用关联侧的manufacturer属性@ManyToOne：
@OneToMany(fetch=FetchType.LAZY,mappedBy="manufacturer")
public Set<MobileDTO> getMobileDTOs() {
return mobileDTOs;
}
