hibernate.PropertyNotFoundException：无法找到具有多级映射的setter Transformer

Question

user_vehicle是我的非持久DTO类，我试图使用hibernate SQLQuery获取同一类的一组记录。用于获取记录

String sql = "select a.user_name as username ,b.vehiclename as \"vehicle.vehicleName\" " 
       + "from user_details a inner join vehicle b on a.user_year = b.vehicleyear;"; 
SQLQuery query = session.createSQLQuery(sql); 
query.addScalar("username",StringType.INSTANCE); 
query.addScalar("vehicle.vehicleName",StringType.INSTANCE); 
query.setResultTransformer(Transformers.aliasToBean(user_vehicle.class)); 
List<user_vehicle> list = query.list(); 
list.forEach(t->System.out.println(t.getUsername()+" -- "+t.getVehicle())); 

我得到错误的 异常线程 “main” org.hibernate.PropertyNotFoundException

public class user_vehicle { 
     private Integer userid; 
     private String username; 
     private Integer userYear; 
    //here is the problem 
     private Vehicle vehicle; 
    //getter and setter 
    } 

public class Vehicle { 
    private Integer vehicleId; 
    private String vehicleName; 
    private Integer vehicleYear; 
//getter setter 
} 

代码：找不到制定者vehicle.vehicleName阶级user_vehicle 。

user_details and vehicle表没有任何关系。

我这样做，这样我可以访问vehicleName作为

list.forEach(t->System.out.println(t.getVehicle().getVehicleName())); 

这里是我的user_details实体类

@Entity(name = "User_Details") 
public class User { 
@Id 
@GeneratedValue(strategy=GenerationType.IDENTITY) 
@Column(name="user_id") 
private Integer userid; 
@Column(name="user_name") 
private String username; 
@Column(name="user_year") 
private Integer userYear; 
//getter and setter 
} 
@Entity 
@Table(name = "Vehicle", catalog = "public", schema = "") 
public class VehicleDetails { 
@Id 
@GeneratedValue(strategy=GenerationType.IDENTITY) 
private Integer vehicleId; 
@Column 
private String vehicleName; 
@Column 
private Integer vehicleYear; 
//getter and setter 
} 

Answer 1

由于异常不能找到设置为vehicle.vehicleName 明确说，你丢失setVechicleName()私人的方法String vehicleName，确保你已经创建它。由于Hibernate将一个Java对象与一个关系表相关联，它使用这些设置器方法在从数据库中获取数据时填充数据。

setVechicleName(String vehicleName) { 

    this.vehicleName = vehicleName; 

} 

Answer 2

如果你想改变一个实体多层次DTO类，我想你应该看这个问题：Populate child bean with Transformers.aliasToBean in Hibernate。它指的是Hibernate Transformers.aliasToBean()的局限性，并提供了一个自定义解决方案来绕过它。

另一解决方案是内联Vehicle DTO在user_vehicle DTO（更常规的类名，没有下划线并用驼峰会更标）：

public class user_vehicle { 
    private Integer userid; 
    private String username; 
    private Integer userYear; 

    private Integer vehicleId; 
    private String vehicleName; 
    private Integer vehicleYear; 
} 

再次另一个解决办法是将如果有关的话当然使用继承。
语义，如果userVehicle是vehicle，它可能是一个合适的解决办法绕过：

public class user_vehicle extends Vehicle{ 
     private Integer userid; 
     private String username; 
     private Integer userYear; 
} 

public class Vehicle { 
    private Integer vehicleId; 
    private String vehicleName; 
    private Integer vehicleYear; 
}