Hi,
what you have done works of course but thats not my problem because
thats what i had before i wanted to do the inverse. Your example
simply demonstrates how to use ElementJoinColumn and i am pretty aware
of that ;-) The problem starts when using mappedBy on the children
inside Father.
When i am doing it as you described it in your email before, i am at
least not getting any errors back but instead he inserts a "null" in
my FK field.
@ManyToOne
@ForeignKey
@JoinColumn(name="team_oid", referencedColumnName="oid")
public Team team;
I am really clueless. It simply cant be so hard and uncommon to make
an inverse OneToMany with a FK field in the child table.
I googled for hours and all example i ve found just dont work.
---
regards
Marc Logemann
http://www.logemann.org
http://www.logentis.de
Am 13.11.2009 um 17:17 schrieb Michael Dick:
Hi Marc,
Did some more reading and I was wrong about the use case for the
@Element
annotations. The @Element annotations allow you to specify the FK
constraint
on the One side of a @OneToMany, so your annotations would look like
this :
@Entity
public class Father extends Person {
@OneToMany
@ElementForeignKey
@ElementJoinColumn(name="father_oid", referencedColumnName="oid")
Collection<Child> children;
. . .
}
@Entity
public class Child extends Person {
@ManyToOne
private Father father;
. . .
}
It appears to be functionally identical to using @JoinColumn and
@ForeignKey
on the Child class, but the documentation is a bit sparse on this
annotation..
There are several examples in our unit tests though. For example
openjpa-persistence-jdbc/src/test/java/org/apache/openjpa/
persistence/jdbc/mapping/bidi/ParentWithAutoIdentity.java
looks somewhat similar to your model.
Hope this helps,
-mike
---------- Forwarded message ----------
From: Michael Dick <[email protected]>
Date: Fri, Nov 13, 2009 at 9:52 AM
Subject: Re: inverse OneToMany relation - getting weird
To: [email protected]
Hi Marc,
I think the @ElementForeignKey and @ElementJoinColumn annotations are
intended to be used with non-entity types (ie PersistentCollections).
If Child is an entity you'd want to use @ForeignKey and @JoinColumn
instead
(I gave this a quick try and it looks like it worked for me).
Regards,
-mike
On Fri, Nov 13, 2009 at 7:03 AM, Marc Logemann <[email protected]>
wrote:
Hi,
after struggling for several hours, i need to ask for help.
Following scenario.....
DB Table: Father
---------------------------
INT oid
....
DB Table: Childs
------------------------
INT oid
INT father_oid
...
Java Entity: Father
--------------------------
...
@OneToMany(cascade = CascadeType.PERSIST, mappedBy = "father")
private List<Child> childList;
Java Entity: Child
--------------------------
...
@ManyToOne(cascade = CascadeType.PERSIST)
@ElementForeignKey
@ElementJoinColumn(name="father_oid", referencedColumnName="oid")
protected Father father;
When i try to persist a Father, i am getting:
<openjpa-1.2.0-r422266:683325 fatal user error>
org.apache.openjpa.persistence.ArgumentException: Field
"Father.childList"
declares "Child.father" as its mapped-by field, but this field is
not a
direct relation. at......
Ok, then i changed Child to:
Java Entity: Child
--------------------------
...
@ManyToOne(cascade = CascadeType.PERSIST)
@Column(name = "father_oid")
protected Father father;
When i now do persist a Father object, both DB records (Father and
Childs)
are filled with records but the FK column in Child (father_oid) is
empty. So
the FK relation is broken but it did persist childs, which is
somehow weird.
So whatever i do, i never get a fully persisted graph with correct FK
values.
Can anyone give me a hint what i am doing wrong here?
Thanks a lot.
---
regards
Marc Logemann
http://www.logemann.org
http://www.logentis.de
