Question

我正在开发一个webapp（Spring J2EE / angularjs）

我想在两个实体之间建立关系：
公民（id，lastName，city）
city（id，cityName）

一个公民只住在一个城市。

我需要从公民那里找到一座城市。我不需要找一个城市的公民。

我做到了：

@Entity
@Table(name = "citizen")
@Cache(usage = CacheConcurrencyStrategy.NONSTRICT_READ_WRITE)
public class Citizen implements Serializable {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;

    @Column(name = "last_name")
    private String lastName;

    @OneToOne
    private City city;
}



@Entity
@Table(name = "city")
@Cache(usage = CacheConcurrencyStrategy.NONSTRICT_READ_WRITE)
public class City implements Serializable {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;

    @Column(name = "city_name")
    private String cityName;
}

在数据库中我插入了数据。公民1,2和3与城市1相关联和Citizen 4与City 2相关联

当我尝试加载所有公民时，我收到错误：找到了多个具有给定标识符的行：1，对于类：com.myApp.rh.domain.Citizen

我的实体出了什么问题？

由于

Answer 1

您的Citizen实体中似乎缺少@JoinColumn注释。

@Entity
@Table(name = "citizen")
@Cache(usage = CacheConcurrencyStrategy.NONSTRICT_READ_WRITE)
public class Citizen implements Serializable {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;

    @Column(name = "last_name")
    private String lastName;

    @OneToOne
    @JoinColumn(name = "id", unique = true)
    private City city;
}



@Entity
@Table(name = "city")
@Cache(usage = CacheConcurrencyStrategy.NONSTRICT_READ_WRITE)
public class City implements Serializable {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;

    @Column(name = "city_name")
    private String cityName;
}

Spring数据：OneToOne关系问题

1 个答案: