Kodo 3.3.3, InverseManager, 1:1 Relation

Question

Hi,
I am evaluating Kodo at the moment and have a problem with the inverse
manager. I have a class 'BaseClassPC' which has a reference to a class
'ReferencedClassPC'. It is a simple 1:1 bidirectional relation, so in
the table for class 'BaseclassPC' I have a column
'REFERENCEDCLASS_JDOID' which points to the JDOID of the referenced
class. I have no foreign key back from REFERENCEDCLASS to BASECLASS.
Now, when I want to set the association between the two objects in my
code this only works when I call baseclass.setReferencedClass(...). When
I try to do it the other way round (referencedclass.setBaseclass(..)) I
get an exception on commit, even though I set kodo.InverseManager=true
in my kodo.properties. The error only occurs when I create both objects
and set the reference within one transaction. Excerpt from the stacktrace:
NestedThrowablesStackTrace:
kodo.util.FatalUserException: Attempt to set column
"BASECLASSPC.REFERENCEDCLASS_JDOID" to two different values:
(null)"null", (class java.lang.Long)"251" This can occur when you fail
to set both sides of a two-sided relation between objects, or when you
map different fields to the same column, but you do not keep the values
of these fields in synch.
     at kodo.jdbc.sql.PrimaryRow.setObject(PrimaryRow.java:215)
     at kodo.jdbc.sql.RowImpl.flushJoinValues(RowImpl.java:267)
     at kodo.jdbc.sql.RowImpl.flushForeignKey(RowImpl.java:189)
     at kodo.jdbc.sql.RowImpl.setForeignKey(RowImpl.java:158)
     at kodo.jdbc.sql.PrimaryRow.setForeignKey(PrimaryRow.java:128)
The doku for the inverse manager says 'Under this setting, Kodo detects
changes to either side of a bidirectional relation, and automatically
sets the other side appropriately on flush.' So I was expecting that it
does not matter on which side I set the relation, nor that I have to set
the relation in two separate transactions, am I wrong?
Here is the sample code, executed in a single transaction:
BaseclassPC base = new BaseclassPC();
ReferencedClassPC ref = new ReferencedClassPC();
//base.setRefClass(ref); <-- works
ref.setSubclass(base); <-- fails
getPersistenceManager().makePersistent(base);
getPersistenceManager().makePersistent(ref);
BTW: It does not matter in which order I make the calls to
makePersistent(...).
Thanks very much,
Jochen

Answer 1

Hi Stephen,
shame on me, I really forgot the put this attribute, sorry that I
bothered you. Another question about the inverse manager: Are there any
limitations that I have to take into account when mapping my classes?
E.g. I read somewhere in this forum that the IM does not work for
horizontal mappings. Background is that I want to switch from another
JDO vendor to Kodo, because the other vendor's implementation of inverse
management was damn buggy, and I want to make sure to have reliable
inverse management this time ;)
Thanks,
Jochen
Stephen Kim wrote:
Did you set the inverse-owner attribute? Kodo will only manasge
inverses which are marked as inverse relations.
Jochen Kressin wrote:
Hi,
I am evaluating Kodo at the moment and have a problem with the inverse
manager. I have a class 'BaseClassPC' which has a reference to a class
'ReferencedClassPC'. It is a simple 1:1 bidirectional relation, so in
the table for class 'BaseclassPC' I have a column
'REFERENCEDCLASS_JDOID' which points to the JDOID of the referenced
class. I have no foreign key back from REFERENCEDCLASS to BASECLASS.
Now, when I want to set the association between the two objects in my
code this only works when I call baseclass.setReferencedClass(...).
When I try to do it the other way round
(referencedclass.setBaseclass(..)) I get an exception on commit, even
though I set kodo.InverseManager=true in my kodo.properties. The error
only occurs when I create both objects and set the reference within
one transaction. Excerpt from the stacktrace:
NestedThrowablesStackTrace:
kodo.util.FatalUserException: Attempt to set column
"BASECLASSPC.REFERENCEDCLASS_JDOID" to two different values:
(null)"null", (class java.lang.Long)"251" This can occur when you fail
to set both sides of a two-sided relation between objects, or when you
map different fields to the same column, but you do not keep the
values of these fields in synch.
at kodo.jdbc.sql.PrimaryRow.setObject(PrimaryRow.java:215)
at kodo.jdbc.sql.RowImpl.flushJoinValues(RowImpl.java:267)
at kodo.jdbc.sql.RowImpl.flushForeignKey(RowImpl.java:189)
at kodo.jdbc.sql.RowImpl.setForeignKey(RowImpl.java:158)
at kodo.jdbc.sql.PrimaryRow.setForeignKey(PrimaryRow.java:128)
The doku for the inverse manager says 'Under this setting, Kodo
detects changes to either side of a bidirectional relation, and
automatically sets the other side appropriately on flush.' So I was
expecting that it does not matter on which side I set the relation,
nor that I have to set the relation in two separate transactions, am I
wrong?
Here is the sample code, executed in a single transaction:
BaseclassPC base = new BaseclassPC();
ReferencedClassPC ref = new ReferencedClassPC();
//base.setRefClass(ref); <-- works
ref.setSubclass(base); <-- fails
getPersistenceManager().makePersistent(base);
getPersistenceManager().makePersistent(ref);
BTW: It does not matter in which order I make the calls to
makePersistent(...).
Thanks very much,
Jochen