java 休眠“ManyToOne ...引用未知实体”异常
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Hibernate "ManyToOne ... references an unknown entity" exception
提问by Gergely Gy?rki
I just cannot get the relationship working between my two classes mapped to SQL tables with Hibernate.
我只是无法使用 Hibernate 将我的两个类之间的关系映射到 SQL 表。
The Role class:
角色类：
@Entity
@Table(name = "role")
public class Role {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name="id")
private int id;
@Column(name="name")
private String name;
@OneToMany(mappedBy="memberinfo")
private Set<Memberinfo> members;
...
}
And the Memberinfo class:
和 Memberinfo 类：
@Entity
@Table(name = "memberinfo")
public class Memberinfo {
@Id @GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name="id", nullable = false)
private int id;
@Column(name = "userid", nullable = false)
private String userid;
@Column(name = "email", nullable = false)
private String email;
@Column(name = "password", nullable = false)
private String password;
@Column(name = "salt", nullable = false)
private String salt;
@Column(name = "name", nullable = false)
private String name;
@Column(name = "address")
private String address;
@Column(name = "phonenum")
private String phonenum;
@ManyToOne(targetEntity=Role.class)
@JoinColumn(name="role_id")
private Role role;
...
}
When i try to fetch data from the DB, it connects, but throws an exception: "HTTP Status 500 - @OneToOne or @ManyToOne on model.Memberinfo.role references an unknown entity: model.Role".
当我尝试从数据库获取数据时，它连接，但抛出异常：“HTTP 状态 500 - @OneToOne 或 @ManyToOne on model.Memberinfo.role 引用了一个未知实体：model.Role”。
If i delete the variable "Role", then it works, and i can fetch the membership data, but i need the connection between the two tables, but in this case, the previously mentioned exception appears every time.
如果我删除变量“Role”，那么它就可以工作，并且我可以获取成员资格数据，但是我需要两个表之间的连接，但是在这种情况下，每次都会出现前面提到的异常。
No other solutions on stackoverflow worked for me so far.
到目前为止，stackoverflow 上没有其他解决方案对我有用。
Any idea what am i doing wrong?
知道我做错了什么吗？
回答by Giuseppe
The "unknown entity error" can be thrown if the class is not actually an Entity (not annotated whith javax.persistence @Entity) or if the persitence provider doesn't "know" the class (package not scanned).
如果该类实际上不是实体（未用 javax.persistence @Entity 注释）或者持久性提供程序不“知道”该类（未扫描包），则可能会抛出“未知实体错误”。
Is the Role class imported in Memberinfo the correct one ? Maybe you are importing another Role class from another library.
Memberinfo 中导入的 Role 类是否正确？也许您正在从另一个库中导入另一个 Role 类。
