Simplest one-to-many Map case in Hibernate doesn't work in MySQL
- by Malvolio
I think this is pretty much the simplest case for mapping a Map (that is, an associative array) of entities.
@Entity
@AccessType("field")
class Member {
@Id
protected long id;
@OneToMany(cascade = CascadeType.ALL, fetch=FetchType.LAZY)
@MapKey(name = "name")
private Map<String, Preferences> preferences
= new HashMap<String, Preferences>();
}
@Entity
@AccessType("field")
class Preferences {
@ManyToOne Member member;
@Column String name;
@Column String value;
}
This looks like it should work, and it does, in HSQL. In MySQL, there are two problems:
First, it insists that there be a table called Members_Preferences, as if this were a many-to-many relationship.
Second, it just doesn't work: since it never populates Members_Preferences, it never retrieves the Preferences.
[My theory is, since I only use HSQL in memory-mode, it automatically creates Members_Preferences and never really has to retrieve the preferences map. In any case, either Hibernate has a huge bug in it or I'm doing something wrong.]
