休眠 - 以一對一的關係

Question

我有兩個表

用戶

CREATE TABLE "user" 
(
    id INTEGER PRIMARY KEY NOT NULL, 
    phone TEXT, 
    position_id BIGINT, 
    CONSTRAINT user_position_id_fk FOREIGN KEY (position_id) REFERENCES position (id) 
); 
CREATE UNIQUE INDEX user_id_uindex ON "user" (id); 

位置

CREATE TABLE position 
(
    id INTEGER PRIMARY KEY NOT NULL, 
    latitude DOUBLE PRECISION, 
    longitude DOUBLE PRECISION, 
    bearing DOUBLE PRECISION, 
    accuracy DOUBLE PRECISION, 
    speed DOUBLE PRECISION, 
    user_id BIGINT, 
    CONSTRAINT position_user_id_fk FOREIGN KEY (user_id) REFERENCES "user" (id) 
); 
CREATE UNIQUE INDEX position_id_uindex ON position (id); 

他們被標註這樣的映射：

@Entity 
@Table(name = "user") 
public class User { 

    public static final String ID = "id"; 
    public static final String PHONE = "phone"; 

    public User() { 
     position = new Position(); 
    } 

    @Id 
    @Column(name = ID, unique = true) 
    @GeneratedValue(strategy = GenerationType.IDENTITY) 
    private long id; 

    @Column(name = PHONE) 
    private String phone; 

    @OneToOne(mappedBy = "user") 
    @Cascade(CascadeType.ALL) 
    @JoinColumn(name = "id", referencedColumnName = "position_id") 
    private Position position; 
} 

@Entity 
@Table(name = "position") 
public class Position { 

    public static final String ID = "id"; 
    public static final String LATITUDE = "latitude"; 
    public static final String LONGITUDE = "longitude"; 
    public static final String BEARING = "bearing"; 
    public static final String ACCURACY = "accuracy"; 
    public static final String SPEED = "speed"; 
    public static final String USER_ID = "user_id"; 

    @Column(name = ID, unique = true) 
    @GenericGenerator(name = "generator", strategy = "foreign", 
      parameters = {@org.hibernate.annotations.Parameter(name = "property", value = "user")}) 
    @Id 
    @GeneratedValue(strategy = GenerationType.IDENTITY) 
    private long id; 

    @Column(name = LATITUDE) 
    private double latitude; 

    @Column(name = LONGITUDE) 
    private double longitude; 

    @Column(name = BEARING) 
    private double bearing; 

    @Column(name = ACCURACY) 
    private double accuracy; 

    @Column(name = SPEED) 
    private double speed; 

    @OneToOne 
    @PrimaryKeyJoinColumn 
    @Cascade(CascadeType.ALL) 
    @JoinColumn(name = "user_id", referencedColumnName = "id") 
    private User user; 
} 

我將新對象保存到數據庫中。除了一件事，一切都是正確的。字段user_id和position_id爲空。有沒有解決方案可以幫助我做到這一點？

Answer 1

這將需要幾個步驟來解決您的問題。

讓我們從一對一關聯開始，只有一個外鍵，您可以決定哪個實體將擁有外鍵。

@joinColumn註釋應該只在擁有實體中，例如，如果您決定用戶將擁有該位置關鍵字作爲外鍵，則@joinColumn註釋將位於位置字段下的用戶實體中。

對其他實體

只使用

@OneToOne(mappedby = "the_matching_field_on_the_other entity") 

例如：

CREATE TABLE "user" 
(
    id INTEGER PRIMARY KEY NOT NULL, 
    phone TEXT, 
    position_id BIGINT, 
    CONSTRAINT user_position_id_fk FOREIGN KEY (position_id) REFERENCES position (id) 
); 

CREATE TABLE position 
(
    id INTEGER PRIMARY KEY NOT NULL, 
    latitude DOUBLE PRECISION, 
    longitude DOUBLE PRECISION, 
    bearing DOUBLE PRECISION, 
    accuracy DOUBLE PRECISION, 
    speed DOUBLE PRECISION, 
); 

@Entity 
@Table(name = "user") 

public class User { 

public static final String ID = "id"; 
public static final String PHONE = "phone"; 

public User() { 
    position = new Position(); 
} 

@Id 
@Column(name = ID, unique = true) 
@GeneratedValue(strategy = GenerationType.IDENTITY) 
private long id; 

@Column(name = PHONE) 
private String phone; 

@OneToOne(cascade = CascadeType.ALL) 
@JoinColumn(name = "id", referencedColumnName = "position_id") 
private Position position; 

}

@Entity 
@Table(name = "position") 
public class Position { 

    public static final String ID = "id"; 
    public static final String LATITUDE = "latitude"; 
    public static final String LONGITUDE = "longitude"; 
    public static final String BEARING = "bearing"; 
    public static final String ACCURACY = "accuracy"; 
    public static final String SPEED = "speed"; 
    public static final String USER_ID = "user_id"; 

    @Column(name = ID, unique = true) 
    @GenericGenerator(name = "generator", strategy = "foreign", 
      parameters = {@org.hibernate.annotations.Parameter(name = "property", value = "user")}) 
    @Id 
    @GeneratedValue(strategy = GenerationType.IDENTITY) 
    private long id; 

    @Column(name = LATITUDE) 
    private double latitude; 

    @Column(name = LONGITUDE) 
    private double longitude; 

    @Column(name = BEARING) 
    private double bearing; 

    @Column(name = ACCURACY) 
    private double accuracy; 

    @Column(name = SPEED) 
    private double speed; 

    @OneToOne(mappedBy = "position") 
    private User user; 
}