英文:
Creating extra column with OneToOne annotation
问题
我有一个用户对象，我需要加载与用户对象一起的组对象。
我已经为此编写了以下代码。
@Entity@Table(name = "User_info")public class UserDao {@Id@GeneratedValue(strategy = GenerationType.AUTO)private int userId;@Column(name="first_name")private String firstName;@Column(name="groupId")private int groupId;@OneToOne(cascade = CascadeType.ALL)@PrimaryKeyJoinColumnprivate GroupMaster groupMaster;//setters and getters}
和 GroupMaster：
@Entity@Table(name = "group_master")public class GroupMaster {@Id@GeneratedValue(strategy = GenerationType.AUTO)private int groupId;@Column(name="groupName")private String groupName;//Setters and getters}
这里的 group_master 是主表，它有 groupId 和 groupname。
我会在 user_info 表中提供 groupId，基于该值，我需要获取 groupMaster 对象。但问题是 Hibernate 正在创建
CREATE TABLE group_master(group_id integer NOT NULL,group_name character varying(255),user_user_id integer NOT NULL,CONSTRAINT group_master_pkey PRIMARY KEY (group_id ),CONSTRAINT fkjxrn8rglp972s1pqfh5tsb6cu FOREIGN KEY (user_user_id)REFERENCES user_info (user_id) MATCH SIMPLEON UPDATE NO ACTION ON DELETE NO ACTION)WITH ( OIDS=FALSE );ALTER TABLE group_master OWNER TO XYZ;
我不知道为什么它创建了 user_user_id 列。我对这个 user_user_id 列没有任何用途。关系应该是与 groupId 相关的。我该如何修复这个问题。
英文:
I have an user object and I need to load group object along with the user object.
I have written for that the following code.
@Entity@Table(name = "User_info")public class UserDao {@Id@GeneratedValue(strategy = GenerationType.AUTO)private int userId;@Column(name="first_name")private String firstName;@Column(name="groupId")private int groupId;@OneToOne(cascade = CascadeType.ALL)@PrimaryKeyJoinColumnprivate GroupMaster groupMaster;//setters and getters}
and GroupMaster:
@Entity@Table(name = "group_master")public class GroupMaster {@Id@GeneratedValue(strategy = GenerationType.AUTO)private int groupId;@Column(name="groupName")private String groupName;//Setters and getters}
Here the group_master is the master table and it has groupId and groupname.
I will give the groupId in user_info table based on that value I need to get the groupMaster object. But the problem here is hibernate is creating
CREATE TABLE group_master(group_id integer NOT NULL,group_name character varying(255),user_user_id integer NOT NULL,CONSTRAINT group_master_pkey PRIMARY KEY (group_id ),CONSTRAINT fkjxrn8rglp972s1pqfh5tsb6cu FOREIGN KEY (user_user_id)REFERENCES user_info (user_id) MATCH SIMPLEON UPDATE NO ACTION ON DELETE NO ACTION)WITH ( OIDS=FALSE );ALTER TABLE group_master OWNER TO XYZ;
I don't know why it creates user_user_id column. I don't have any use with this user_user_id column. The relation should be with groupId. How can I fix it.
答案1
得分: 1
@Entity@Table(name = "User_info")public class UserDao {@Id@GeneratedValue(strategy = GenerationType.AUTO)private int userId;@Column(name="first_name")private String firstName;@OneToOne(cascade = CascadeType.ALL)private GroupMaster groupMaster;//setters and getters}
英文:
You don't need a separate groupId-column or the @PrimaryKeyJoinColumn Annotation
Change your UserDao to:
@Entity@Table(name = "User_info")public class UserDao {@Id@GeneratedValue(strategy = GenerationType.AUTO)private int userId;@Column(name="first_name")private String firstName;@OneToOne(cascade = CascadeType.ALL)private GroupMaster groupMaster;//setters and getters}
答案2
得分: 0
你应该在双方都定义@OneToOne关系，因此你需要在GroupMaster中添加@OneToOne注解，以正确的方式进行操作，你应该像这样做：
在UserDao中：
@Entity@Table(name = "User_info")public class UserDao {@Id@GeneratedValue(strategy = GenerationType.AUTO)private int userId;@Column(name="first_name")private String firstName;@OneToOne(mappedBy = "user")GroupMaster group;//setters and getters}
然后GroupMaster实体应该像这样：
@Entity@Table(name = "group_master")public class GroupMaster {@Id@GeneratedValue(strategy = GenerationType.AUTO)private int groupId;@Column(name="groupName")private String groupName;@OneToOne@PrimaryKeyJoinColumnUserDao user;//Setters and getters}
英文:
you should define the @OneToOne relationship in both sides so you need to add the @OneToOne annotation to the GroupMaster too, to make it in the properly way you should do it like this :
@Entity@Table(name = "User_info")public class UserDao {@Id@GeneratedValue(strategy = GenerationType.AUTO)private int userId;@Column(name="first_name")private String firstName;@OneToOne(mappedBy = "user")GroupMaster group;//setters and getters}
then the GroupMaster Entity should be like this :
@Entity@Table(name = "group_master")public class GroupMaster {@Id@GeneratedValue(strategy = GenerationType.AUTO)private int groupId;@Column(name="groupName")private String groupName;@OneToOne@PrimaryKeyJoinColumnUserDao user;//Setters and getters}
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