玩框架加入表(Play Framework Join Table)

 我想要做的是根据用户ID将表连接到另一个表。 
 
 我有一个用户表，以及一个警报历史记录表，其中包含与用户ID相关联的外键。 
 
 我使用的是Netbeans 7.4生成的实体。 
 
 用户： 
 
    @Entity
@Table(name = "Users", schema = "dbo")
public class User extends Model implements Serializable {
    private static final long serialVersionUID = 1L;
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Basic(optional = false)
    @Column(name = "UserID")
    private Integer userID;
            @OneToMany(cascade = CascadeType.ALL, fetch = FetchType.EAGER, mappedBy = "userId")
            private Collection<AlertHistory> alertHistoryCollection;
     { ... }
 
 警报历史： 
 
    @Entity
@Table(name = "Alert_History", schema = "dbo")
public class AlertHistory extends Model implements Serializable {
    private static final long serialVersionUID = 1L;
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Basic(optional = false)
    @Column(name = "id")
    private Long id;
    @Basic(optional = false)
    @Column(name = "user_id")
    @ManyToOne(fetch = FetchType.EAGER)
    private int userId;
    @Basic(optional = false)
    @Column(name = "message_id")
    private long messageId;
    @Basic(optional = false)
    @Lob
    @Column(name = "alerts_triggered")
    private String alertsTriggered;
            {...}
 
 我期望的是，当我加载用户时，它将尝试基于userId加入AlertsHistory表结果。 但是，在运行时， AlertsHistory Collection始终为null 
 
 更新：已解决 
 
 我看错了方法。 为了进行JOIN，AlertHistory期望被传递一个User对象，而不仅仅是userId键。 将User字段添加到AlertHistory模型，并将@OneToMany(mappedBy = "userId")更改为@OneToMany(mappedBy = "user" ，然后添加@JoinColumn(name="user_id", referencedColumnName="userId") private User user;在AlertHistory那个User字段让我整理好了！感谢大家的帮助。 

What I'm trying to do is to join a table to another table based on a user id.
 
I have a user table, and an alerts history table that has a foreign key associated with the user's ID.
 
I am using entities generated by Netbeans 7.4.
 
User:
 
    @Entity
@Table(name = "Users", schema = "dbo")
public class User extends Model implements Serializable {
    private static final long serialVersionUID = 1L;
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Basic(optional = false)
    @Column(name = "UserID")
    private Integer userID;
            @OneToMany(cascade = CascadeType.ALL, fetch = FetchType.EAGER, mappedBy = "userId")
            private Collection<AlertHistory> alertHistoryCollection;
     { ... }
 
Alert History:
 
    @Entity
@Table(name = "Alert_History", schema = "dbo")
public class AlertHistory extends Model implements Serializable {
    private static final long serialVersionUID = 1L;
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Basic(optional = false)
    @Column(name = "id")
    private Long id;
    @Basic(optional = false)
    @Column(name = "user_id")
    @ManyToOne(fetch = FetchType.EAGER)
    private int userId;
    @Basic(optional = false)
    @Column(name = "message_id")
    private long messageId;
    @Basic(optional = false)
    @Lob
    @Column(name = "alerts_triggered")
    private String alertsTriggered;
            {...}
 
What I would expect is that when I load a user, it will attempt to join the AlertsHistory table results based on the userId. However, at runtime, the AlertsHistory Collection is always null
 
Update: SOLVED
 
I was looking at this the wrong way. In order to do a JOIN, AlertHistory was expecting to be handed a User object, and not just the userId key. Adding a User field to the AlertHistory model, and changing the @OneToMany(mappedBy = "userId") to @OneToMany(mappedBy = "user", then adding @JoinColumn(name="user_id", referencedColumnName="userId") private User user; to that User field in AlertHistory got me sorted out! Thanks for the help everyone.

原文：https://stackoverflow.com/questions/21266049