英文:
JPA OneToOne and ManyToOne relationship with same entity
问题
我在Java世界和JPA中还是新手。我在OneToMany关系方面遇到了问题。
我有两个实体：UserEntity和ManagerEntity。
Manager是一个被提升的User，所以在这里我们有一个OneToOne关系，managers表中的manager_uuid引用了users表中的uuid。这个关系运行良好。
现在每个Manager有许多clients，即UserEntity，它由managers表进行映射。
问题是它一直在寻找users表中的client_uuid，而不是managers，我不知道为什么...
@Entity@Table(name = "users")public class UserEntity {@Id@GeneratedValue(strategy = AUTO)private UUID uuid;@OneToOne@JoinColumn(name = "manager_uuid",referencedColumnName = "uuid")private ManagerEntity managerReference;@ManyToOne@JoinColumn(name = "client_uuid",referencedColumnName = "uuid")private ManagerEntity manager;}@Entity@Table(name = "managers")public class ManagerEntity {@Id@GeneratedValue(strategy = AUTO)private UUID uuid;@OneToOne(mappedBy = "managerReference")private UserEntity actingManager;@OneToMany(mappedBy = "manager")private List<UserEntity> clients = new ArrayList<>();}
迁移：
CREATE TABLE IF NOT EXISTS managers(uuid uuid DEFAULT gen_random_uuid() PRIMARY KEY,manager_uuid uuid NOT NULL,client_uuid uuid NOT NULL,created_at TIMESTAMP NOT NULL,updated_at TIMESTAMP NOT NULL,FOREIGN KEY (manager_uuid) REFERENCES users (uuid),FOREIGN KEY (client_uuid) REFERENCES users (uuid))
错误信息：
> 错误：列userentity0_.client_uuid不存在
我做错了什么，有任何想法吗？
英文:
I'm new in Java world, and JPA. I have a problem with OneToMany relationships.
So I have two entities: UserEntity and ManagerEntity.
The Manager is a User that was promoted, so here we have OneToOne relationship where manager_uuid in managers table reference uuid in the users table. This relationship works fine.
Now each Manager has many clients => UserEntity and it is mapped by managers table.
The problem is that it keeps looking for client_uuid in the users table instead of managers and I don't know why...
@Entity@Table(name = "users")public class UserEntity {@Id@GeneratedValue(strategy = AUTO)private UUID uuid;@OneToOne@JoinColumn(name = "manager_uuid",referencedColumnName = "uuid")private ManagerEntity managerReference;@ManyToOne@JoinColumn(name = "client_uuid",referencedColumnName = "uuid")private ManagerEntity manager;}@Entity@Table(name = "managers")public class ManagerEntity {@Id@GeneratedValue(strategy = AUTO)private UUID uuid;@OneToOne(mappedBy = "managerReference")private UserEntity actingМanager;@OneToMany(mappedBy = "manager")private List<UserEntity> clients = new ArrayList<>();}
Migration:
CREATE TABLE IF NOT EXISTS managers(uuid uuid DEFAULT gen_random_uuid() PRIMARY KEY,manager_uuid uuid NOT NULL,client_uuid uuid NOT NULL,created_at TIMESTAMP NOT NULL,updated_at TIMESTAMP NOT NULL,FOREIGN KEY (manager_uuid) REFERENCES users (uuid),FOREIGN KEY (client_uuid) REFERENCES users (uuid))
The error:
> ERROR: column userentity0_.client_uuid does not exist
Any idea what I'm doing wrong?
答案1
得分: 1
这是预期的工作方式。client_uuid 是需要存在于用户表中的内容。由于一个经理可能有多个客户，所以不能将多个 client_uuid 插入到经理表的单个字段中。但是当情况反过来时，一个用户只会有一个经理。因此，他们可以轻松存储 manager_uuid。
您可以尝试将代码编写如下：
CREATE TABLE IF NOT EXISTS managers(uuid uuid DEFAULT gen_random_uuid() PRIMARY KEY,manager_uuid uuid NOT NULL,created_at TIMESTAMP NOT NULL,updated_at TIMESTAMP NOT NULL,FOREIGN KEY (manager_uuid) REFERENCES users (uuid))CREATE TABLE IF NOT EXISTS users(uuid uuid DEFAULT gen_random_uuid() PRIMARY KEY,client_uuid uuid NOT NULL,created_at TIMESTAMP NOT NULL,updated_at TIMESTAMP NOT NULL,FOREIGN KEY (client_uuid) REFERENCES managers(uuid))
英文:
It's working as expected. The client_uuid is something which needs to be in user table. As one manager will be having multiple clients, you can't insert multiple client_uuid in manager table single field. But when it comes the other way around than one user will be having only one manager. So they can store the manager_uuid easily.
You can try make your code like below:
CREATE TABLE IF NOT EXISTS managers(uuid uuid DEFAULT gen_random_uuid() PRIMARY KEY,manager_uuid uuid NOT NULL,created_at TIMESTAMP NOT NULL,updated_at TIMESTAMP NOT NULL,FOREIGN KEY (manager_uuid) REFERENCES users (uuid))CREATE TABLE IF NOT EXISTS users(uuid uuid DEFAULT gen_random_uuid() PRIMARY KEY,client_uuid uuid NOT NULL,created_at TIMESTAMP NOT NULL,updated_at TIMESTAMP NOT NULL,FOREIGN KEY (client_uuid) REFERENCES managers(uuid))
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