Hello,
I am writing some code (for learning / proof of concept) and I am
using OpenJPA for the persistence framework.
Right now, I have two objects - User and Subscription. There is a
OneToMany relationship that one user can have many Subscriptions (or
none). A subscription should have a composite key based on two of it's
own string fields and the user object that it is linked to...
Here is how I have it coded currently -
User.java -
@Entity
@Table(name="reader_users")
public class User {
@Id
@Column(length=32)
private String username;
@Column(length=64)
private String fromAddress;
@Column(length=255)
private String fullName;
@Column(length=32)
private String password;
@Column(length=255)
private String replyToAddress;
@OneToMany(cascade =PERSIST)
private List<Subscription> subscriptions;
...
}
Subscription.java -
@Entity
@Table(name="reader_subscriptions")
@IdClass(Subscription.SubscriptionPK.class)
public class Subscription {
@Id
@Column(name="host", length=255)
private String host;
@Column(name="server_type", length=16)
private String type;
@Id
@Column(name="username", length=32)
private String username;
@Column(name="password", length=32)
private String password;
@Column(name="auto_connect")
private boolean autoConnect;
@Id
@ManyToOne
@JoinColumn(name="username")
private User user;
public static class SubscriptionPK {
private String host;
private String username;
private User user;
@Override
public int hashCode() {
...
}
@Override
public boolean equals(Object obj) {
...
}
...
}
...
}
In the code above, the '...' represent where I've snipped the code for
the sake of bandwidth. I am new to JPA and I could be doing something
wrong, so I am looking for feedback. Specifically, when I run the
mapping tool, I get the following error message -
Exception in thread "main" <openjpa-1.0.0-r420667:568756 fatal user
error> org.apache.openjpa.util.MetaDataException: The id class
specified by type "class
org.apache.struts2.apps.mailreader.jpa.Subscription" does not match
the primary key fields of the class. Make sure your identity class
has the same primary keys as your persistent type, including pk field
types. Mismatched property: "user"
Right now, I suppose that the combination of host/username/user does
not need to be the primary key. If it's not, is there a way I can
enforce uniqueness? Is this just a crappy design and I should be doing
it differently?
--
Wesley Wannemacher
President, Head Engineer/Consultant
WanTii, Inc.
http://www.wantii.com
