更新和/或删除时违反 Hibernate H2 参照完整性约束

Question

So I am currently building a database for a university project. In the database, we are going to have an object that references a user. Users should be able to freely add, edit, and remove entries from the database.

I am able to create, edit, and delete users, so long as they are not assigned an experimenting station where they will be working. As soon as they are assigned to one, I start getting the error:

Referential integrity constraint violation: "FKGQN2NFAK1N6TWN592B0KQ34IT: PUBLIC.EXPERIMENTIERSTATION_USER FOREIGN KEY(BENUTZER_ID) REFERENCES PUBLIC.USER(ID) (.......)"; SQL statement:
delete from User where id=?

Now I do kind of understand why this is happening, hence why the ExperimentingStation attribute has a reference to the User and vice versa. However, even when setting the CascadeType to MERGE , I still get the error, which I do not quite understand. We are using Hibernate with it's default configuration, so I understand we do not need to worry about the Table names, which is why they are not included in the following code, however, I do not know how to use mappedBy without the names.

Another issue is that we are trying to persist a Queue within ExperimentingStation which also isn't working.

Any help would be appreciated!

Thanks a lot in advance

The code:

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;
    }
}

Answer 1

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，并且只从数据库中获取 Valid 元素，这可以完美地工作。