java - Spring 一对一关系

Question

我有一个非常简单的问题。我不知道是我没有理解什么，还是我不知道该怎么做。我很长一段时间想知道hibernate spring中如何一对一。我可以从两个方向到达 table 。假设我有 Hotel 和 hotelDetails 表。正在为我创建一个 key ，以便我可以从酒店访问 hotelRating，但我不能走其他路。有时这对我很重要。我将使用示例代码。

public class Hotel {

    private Long id;
    private String name;
    private String currency;
    private String image;
    private HotelRating hotelRating;


    @Id
    @Column(name = "id")
    @GeneratedValue(strategy = GenerationType.AUTO)
    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }
.
    .
    @OneToOne(cascade = CascadeType.ALL)
    @JoinColumn(name = "hotel_rating_id", referencedColumnName = "id")
    public HotelRating getHotelRating() {
        return hotelRating;
    }

    public void setHotelRating(HotelRating hotelRating) {
        this.hotelRating = hotelRating;
    }

酒店评级表。

问题是，当我试图让 getter 和 setter 做 hotel 时。我得到:

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'entityManagerFactory' defined in class path resource [org/springframework/boot/autoconfigure/orm/jpa/HibernateJpaConfiguration.class]: Invocation of init method failed; nested exception is javax.persistence.PersistenceException: [PersistenceUnit: default] Unable to build Hibernate SessionFactory; nested exception is org.hibernate.MappingException: Could not determine type for: com.flightradar.flightradar.model.hotel.Hotel, at table: hotel_rating, for columns: [org.hibernate.mapping.Column(hotel)]

@Entity
@Table(name = "hotel_rating")
public class HotelRating {

    private long id;

    private Integer votesNumber;

    @Min(1)
    @Max(5)
    private Double average;

    @OneToOne(mappedBy = "hotel_rating")
    Hotel hotel;



    @Id
    @Column(name = "id")
    @GeneratedValue(strategy = GenerationType.AUTO)
    public long getId() {
        return id;
    }

    public void setId(long id) {
        this.id = id;
    }

    public Integer getVotesNumber() {
        return votesNumber;
    }

    public void setVotesNumber(Integer votesNumber) {
        this.votesNumber = votesNumber;
    }

    public Double getAverage() {
        return average;
    }

    public void setAverage(Double average) {
        this.average = average;
    }

}

所以，大家帮助我了解从 HotelRating Table 到达 Hotel table 的最简单的可能性。例如，我有 HotelRating 列表，我必须从 Hotel 表中获取每个 hotelRanking 对象。

Answer 1

HotelRating 类中的“mappedBy”值必须提供

The field that owns the relationship.

在您的示例中，值为“hotel_ rating”

 @OneToOne(mappedBy = "hotel_rating")
 Hotel hotel;

但是Hotel类中没有这样的字段。相应的字段可能是“hotelRating”。