JPA与EclipseLink ManyToMany关系不起作用

Question

我试图设置一个像电话目录的应用程序，其中每个用户可以有多个电话，每个电话可以分配给多个用户。我正在使用JPA和EclipseLink来完成这项工作。在检索其中一个表时，JPA正在抛出一个异常。 详情如下 -
异常跟踪 -

com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: Unknown column 't0.users_ID' in 'where clause' 
Error Code: 1054 
Call: SELECT t1.ID, t1.FIRSTNAME, t1.LASTNAME, t1.TITLE, t1.CITY, t1.STATE, t1.STREET, t1.ZIP FROM Phone_User t0, User t1 WHERE ((t0.Phone_ID = ?) AND (t1.ID = t0.users_ID)) 
    bind => [1 parameter bound] 
Query: ReadAllQuery(name="users" referenceClass=User sql="SELECT t1.ID, t1.FIRSTNAME, t1.LASTNAME, t1.TITLE, t1.CITY, t1.STATE, t1.STREET, t1.ZIP FROM Phone_User t0, User t1 WHERE ((t0.Phone_ID = ?) AND (t1.ID = t0.users_ID))") (through reference chain: edu.lab2.beans.Phone["users"]); 

User.java

@Entity 
@Table(name = "User") 
public class User { 

@Id 
@GeneratedValue(strategy = GenerationType.SEQUENCE) 
private Long id; 

private String firstname; 
private String lastname; 
private String title; 

@Embedded 
private Address address; 

@ManyToMany 
@JoinTable(name = "Phone_User", joinColumns = @JoinColumn(name = "user_id", referencedColumnName = "id"), inverseJoinColumns = @JoinColumn(name = "phone_id", referencedColumnName = "id")) 
private List<Phone> phones; 

Phone.java

@Entity 
@Table(name = "Phone") 
public class Phone { 

@Id 
@GeneratedValue(strategy = GenerationType.SEQUENCE) 
private Long id; 
private String number; // Note, phone numbers must be unique 
private String description; 

@Embedded 
private Address address; 

private List<User> users; 

@ManyToMany(mappedBy="phones") 
public List<User> getUsers() { 
    return users; 
} 

表 -

mysql> DESC User; 
+-----------+-------------+------+-----+---------+----------------+ 
| Field  | Type  | Null | Key | Default | Extra   | 
+-----------+-------------+------+-----+---------+----------------+ 
| id  | int(11)  | NO | PRI | NULL | auto_increment | 
| firstname | varchar(40) | YES |  | NULL |    | 
| lastname | varchar(40) | YES |  | NULL |    | 
| title  | varchar(10) | YES |  | NULL |    | 
| street | varchar(40) | YES |  | NULL |    | 
| city  | varchar(40) | YES |  | NULL |    | 
| state  | varchar(40) | YES |  | NULL |    | 
| zip  | varchar(20) | YES |  | NULL |    | 
+-----------+-------------+------+-----+---------+----------------+ 
| state  | varchar(40) | YES |  | NULL |    | 
8 rows in set (0.03 sec) 

mysql> DESC Phone; 
+-------------+-------------+------+-----+---------+----------------+ 
| Field  | Type  | Null | Key | Default | Extra   | 
+-------------+-------------+------+-----+---------+----------------+ 
| id   | int(11)  | NO | PRI | NULL | auto_increment | 
| number  | varchar(20) | YES | UNI | NULL |    | 
| description | varchar(20) | YES |  | NULL |    | 
| street  | varchar(40) | YES |  | NULL |    | 
| city  | varchar(40) | YES |  | NULL |    | 
| state  | varchar(40) | YES |  | NULL |    | 
| zip   | varchar(20) | YES |  | NULL |    | 
+-------------+-------------+------+-----+---------+----------------+ 
7 rows in set (0.00 sec) 

mysql> DESC Phone_User; 
+----------+---------+------+-----+---------+-------+ 
| Field | Type | Null | Key | Default | Extra | 
+----------+---------+------+-----+---------+-------+ 
| user_id | int(11) | NO | PRI | NULL |  | 
| phone_id | int(11) | NO | PRI | NULL |  | 
+----------+---------+------+-----+---------+-------+ 
2 rows in set (0.01 sec) 

我很困惑为什么EclipseLink或JPA在联接表中搜索users_id？

Answer 1

Phone实体混合了字段和属性访问类型（请参阅JPA 2.1规范，第2.3章）。尝试在private List<User> users字段上放置@ManyToMany(mappedBy="phones")注释。

如果你真的需要字段和属性（读：干将）之间分割的注释，你可以用@Access(AccessType.PROPERTY)注释特定的属性，即在这种情况下：

@Access(AccessType.PROPERTY) 
@ManyToMany(mappedBy="phones") 
public List<User> getUsers() { 
    return users; 
}