春季休息休眠OneToMany / ManyToOne

Question

I'm trying to create a user table that has a OneToMany relationship using the username as a foreign key, however the username field in the ManyToOne relationship is coming through as Null every time.

Relationships:

User:

    @OneToMany(targetEntity = Authority.class, cascade=CascadeType.ALL, mappedBy="username")
    private Collection<Authority> authorities

Authority:

    @Column(nullable = false, name="username")
    @JoinColumn(name="user_username")
    String username;

resulting tables:

+----+--------------------+-----------+---------+
| id | username           | password  | enabled |
+----+--------------------+-----------+---------+
| 13 | will               | q         |       0 |
| 34 | I just got editted | adufhasdf |       1 |
| 36 | wakakawakwakaak    | ballz     |       0 |
+----+--------------------+-----------+---------+

+----+----------+------------+
| id | username | authority  |
+----+----------+------------+
|  6 | NULL     | ROLE_ADMIN |
|  7 | NULL     | ROLE_ADMIN |
|  8 | NULL     | ROLE_ADMIN |
| 12 | NULL     | ROLE_BASIC |
| 13 | NULL     | ROLE_BASIC |
| 14 | NULL     | ROLE_BASIC |
| 17 | NULL     | ROLE_BASIC |
| 18 | NULL     | ROLE_BASIC |
| 19 | NULL     | ROLE_BASIC |
| 20 | NULL     | ROLE_BASIC |
| 21 | NULL     | ROLE_BASIC |
| 22 | NULL     | none       |
| 23 | NULL     | ROLE_BASIC |
| 24 | NULL     | ROLE_BASIC |
| 25 | NULL     | none       |
| 26 | NULL     | none       |
| 27 | NULL     | ROLE_BASIC |
| 28 | NULL     | none       |
| 29 | NULL     | ROLE_ADMIN |
| 30 | NULL     | ROLE_ADMIN |
| 31 | NULL     | ROLE_BASIC |
| 39 | NULL     | ROLE_BASIC |
| 40 | NULL     | ROLE_USER  |
| 41 | NULL     | ROLE_USER  |
| 42 | NULL     | ROLE_USER  |
| 43 | NULL     | ROLE_ADMIN |
| 44 | NULL     | ROLE_ADMIN |
| 45 | NULL     | ROLE_USER  |
+----+----------+------------+

Answer 1

Your JoinColumn should be:

@JoinColumn(name="username")

This is because the field is identified as username in the Authority entity.

Answer 2

I think the reason is from the many-to-one side, you have to use the User object instead of the String. Here is what i tried and it works.

//User

@OneToMany(targetEntity = Authority.class, fetch = FetchType.EAGER, mappedBy = "user")
private Collection<Authority> authorities;

//Authority

@ManyToOne
@JoinColumn(name="username", referencedColumnName = "username")
private User user;

Results:

Hope this help!

Answer 3

A simple answer turned up in the JPA docs.

In user

@OneToMany(targetEntity = Authority.class , cascade = CascadeType.ALL)
@JoinColumn(name="username", referencedColumnName="username")
private List<Authority> authorities

and then the Authority

@Column(nullable = false)
String username;