一对多类中，根据多的的一方的某个属性获得一的一方的list

Posted 2020-10-11 发福大叔

一的一方：AppVsStaff.java

AppVsStaff中包含两个多的一方，Applications.java和StaffDict.java

import org.hibernate.annotations.NotFound;
import org.hibernate.annotations.NotFoundAction;
import javax.persistence.*;
import javax.validation.constraints.NotNull;
import javax.validation.constraints.Size;

@Entity
@Table(name = "APP_VS_STAFF")
public class AppVsStaff {
  @Id
  @Column(name="APP_VS_EMP_ID")
  @NotNull(message = "应用程序人员关系ID不能为空")
  @Size(min = 1,max = 20,message = "应用程序人员关系ID不能超过20字且不能为空")
  private String  AppVsEmpId;

  @JoinColumn(name = "APP_ID")
  @ManyToOne
  @NotFound(action = NotFoundAction.IGNORE)
  private Applications applications;

  @JoinColumn(name = "EMP_ID")
  @ManyToOne
  @NotFound(action = NotFoundAction.IGNORE)
  private StaffDict staffDict;

  @Column(name="CAPABILITY")
  private String capability;
}

问题：要根据StaffDict中的某个属性查出Applications对应的list

解决如下：

List<Applications> appList = new ArrayList<>();
String jpql = "SELECT app FROM AppVsStaff appVsStaff LEFT JOIN appVsStaff.applications app WHERE appVsStaff.staffDict.userName=:userName";
appList = entityManager.createQuery(jpql).setParameter("userName", userName).getResultList();