所以我目前正在为一个大学项目建立一个数据库。 在数据库中,我们将有一个引用用户的对象。用户应该能够自由地添加、编辑和删除数据库中的条目。
我可以创建、编辑和删除用户,只要他们没有被分配到他们将工作的实验站即可。一旦它们被分配给一个,我就开始收到错误:
Referential integrity constraint violation: "FKGQN2NFAK1N6TWN592B0KQ34IT: PUBLIC.EXPERIMENTIERSTATION_USER FOREIGN KEY(BENUTZER_ID) REFERENCES PUBLIC.USER(ID) (.......)"; SQL statement:
delete from User where id=?
现在我确实有点理解为什么会发生这种情况,因此为什么 ExperimentingStation
属性引用了 User,反之亦然。
但是,即使将 CascadeType 设置为 MERGE,我仍然收到错误,我不太明白。我们使用 Hibernate 的默认配置,所以我知道我们不需要担心表名称,这就是为什么它们没有包含在下面的代码中,但是,我不知道如何在没有名称的情况下使用 mappedBy
。
另一个问题是,我们试图在 ExperimentingStation
中保留一个队列,但该队列也不起作用。
如有任何帮助,我们将不胜感激!
提前非常感谢
代码:
Class ExperimentierStation:
import lombok.*;
import javax.persistence.*;
import java.util.List;
import java.util.Queue;
/** Experimenting stations data class */
@Data
@Entity
@NamedQueries({
@NamedQuery(name = "ExperimentierStation.findAllInLocation",
query = "SELECT es FROM ExperimentierStation es WHERE es.standort = :standort"),
@NamedQuery(name = "ExperimentierStation.getByStatus",
query = "SELECT es FROM ExperimentierStation es WHERE es.status = :status"),
@NamedQuery(name = "ExperimentierStation.getAll", query = "SELECT es FROM ExperimentierStation es")
})
@RequiredArgsConstructor
@NoArgsConstructor
public class ExperimentierStation {
/** The station's id */
@NonNull
@Id
private int esID;
/** The station's location */
@NonNull
@ManyToOne
private Standort standort;
@NonNull
private String name;
/** The station's status */
@NonNull
private Enum<ExperimentierStationZustand> status;
/** Conditions for using an experimenting station */
@OneToMany
private List<Bedingung> bedingungen;
@NonNull
@ManyToMany(cascade=CascadeType.MERGE, fetch = FetchType.LAZY)
private List<User> benutzer;
@OneToOne
private ProzessSchritt currentPS;
}
Class User:
import lombok.*;
import javax.persistence.*;
import javax.ws.rs.Path;
import java.time.LocalDateTime;
import java.util.List;
/**
* This class is used to create user objects
*/
@Data
@Entity
@NamedQueries({
@NamedQuery(name = "User.findById", query = "SELECT u from User u WHERE u.id = :id"),
@NamedQuery(name = "User.findByUsername", query = "SELECT u from User u WHERE u.username = :username"),
@NamedQuery(name = "User.findByEmail", query = "SELECT u from User u WHERE u.email = :email"),
@NamedQuery(name = "User.getAll", query = "SELECT u FROM User u")
})
@RequiredArgsConstructor(access = AccessLevel.PUBLIC)
@NoArgsConstructor(access = AccessLevel.PUBLIC)
public class User {
/**
* User's id
*/
@Id
@NonNull
private int id;
/**
* The user's name
*/
@NonNull
private String vorname;
/**
* The user's surname
*/
@NonNull
private String nachname;
/**
* User's email address
*/
@NonNull
private String email;
/**
* The user's phone number
*/
@NonNull
private String telefonnummer;
/**
* User's username
*/
@NonNull
private String username;
/**
* User's hashed password
*/
@NonNull
private String password;
/**
* Is the user verified?
*/
@NonNull
private boolean wurdeVerifiziert;
/**
* Creation date of the user object
*/
@NonNull
private LocalDateTime erstellungsDatum;
/**
* The role's of the user
*/
@NonNull
@ElementCollection
private List<Role> rollen;
/**
* The User's language preference
*/
@NonNull
private String language;
public String toString() {
return vorname + nachname;
}
}
最佳答案
经过深思熟虑,我们决定不完全从实体管理器中删除对象,而只是向每个元素添加一个 VALID boolean 值,并仅从数据库中获取 Valid 元素,这样可以完美地工作。
关于java - 更新和/或删除时违反 Hibernate H2 引用完整性约束,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/60303929/