Hi Peter,
it looks like you are using a unidirectional relation between Stuff and
Thing. Castor docs say this is not supported. While I use
unidirectional mappings in some cases I never did so for many to many
relations. Therefore I am not sure if this really is the reason for
your problem but chances are quite high.
I suggest you to use a bidirectional mapping for many to many relations
(Stuff references Thing and Thing references Stuff). In addition you
have to care that both sides of the relation are in sync before you
call one of Castor's methods to persist your objects.
public static void testStuffAndThings() {
Database database = jdoManager.getDatabase();
database.begin();
Thing thing = new Thing(1,"My Thing");
database.create(thing);
Stuff stuff = new Stuff(1,"My Stuff");
database.create(stuff);
stuff.setThings(new ArrayList());
stuff.getThings().add(thing);
thing.setStuffs(new ArrayList());
thing.getStuffs().add(stuff);
database.commit();
database.begin();
stuff = (Stuff) database.load(Stuff.class, 1);
thing = stuff.getThings().remove(0);
thing.getStuffs().remove(0);
database.remove(thing);
database.commit();
database.close();
}
P.S. At the moment I working at a project that also uses PostgreSQL
together with Castor. During this project I recognized some issues in
Castor related to the handling of identifier names (table and column
names) of PostgreSQL. If you want to use upper case identifier names
you will need to use SVN head where I already fixed all these issues.
Lower case identifier names will work with 1.3.
Regards
Ralf
peter cowan schrieb:
werner,
there are two foreign keys in the stuff_and_things table:
"stuff_and_things_stuff_id_fkey" FOREIGN KEY (stuff_id)
REFERENCES stuff(id)
"stuff_and_things_thing_id_fkey" FOREIGN KEY (thing_id)
REFERENCES things(id)
also, for total completeness, we are using castor 1.3, our database is
postgresql 8.1 and
we are using postgresql-8.1-407.jdbc3.jar
what is the expected behavior in the scenarios i laid out?
-peter
On Wed, Sep 2, 2009 at 1:06 AM, Werner
Guttmann <[email protected]>
wrote:
Peter,
can you please highlight the (e.g. foreign key) constraints in your SQL
schema, just for completeness ?
Regards
Werner
peter cowan wrote:
> I have a pretty standard many-to-many relation mostly working, I
can create
> , load and update objects fine, and the database tables populate as
> expected, however when I try to remove objects I am running into
trouble.
> Below is a database description, the mapping and some example code.
>
> database tables:
>
> table - stuff:
> id - int
> name - varchar
>
> table - things:
> id - int
> name - varchar
>
> table - stuff_and_things:
> id - int
> stuff_id - int
> thing_id - int
>
> <mapping>
> <class name="my.test.app.Stuff" identity="id">
> <map-to table="stuff"/>
> <field name="id" type="int">
> <sql name="id" type="integer" />
> </field>
> <field name="name" type="string">
> <sql name="name" type="varchar" />
> </field>
> <field name="things" type="my.test.app.Thing"
> collection="arraylist">
> <sql name="stuff_id"
> many-table="stuff_and_things"
> many-key="thing_id" />
> </field>
> </class>
>
> <class name="my.test.app.Thing" identity="id">
> <map-to table="things" />
> <field name="id" type="int">
> <sql name="id" type="integer" />
> </field>
> <field name="name" type="string">
> <sql name="name" type="varchar" />
> </field>
> </class>
> </mapping>
>
> Both Stuff and Thing are simple Java Beans and nothing more.
>
> In the below example, the objects are created correctly in the
first
> transaction, and loaded correctly in the second transaction. When
I try to
> remove a Thing from the ArrayList data member of Stuff, the Thing
is only
> removed from the relation table stuff_and_things, and an orphan is
left in
> the things table. This makes enough sense, however, when I try to
then
> remove the Thing from the database by uncommenting
> 'database.remove(thing);', I get an exception that it can't be
removed due
> to foreign key constraints in stuff_and_things. This also makes
sense, but I
> am left wondering, what am I doing wrong? How do I go about
deleting those
> orphaned records without doing it in a second transaction?
>
> public static void testStuffAndThings() {
> Database database = jdoManager.getDatabase();
> database.begin();
>
> Thing thing = new Thing(1,"My Thing");
> Stuff stuff = new Stuff(1,"My Stuff");
> ArrayList things = new ArrayList();
> things.add(thing);
> stuff.setThings(things);
>
> database.create(thing);
> database.create(stuff);
> database.commit();
>
> database.begin();
> stuff = (Stuff) database.load(Stuff.class, 1);
> things = stuff.getThings();
> thing = things.remove(0);
> //database.remove(thing);
> database.commit();
> database.close();
> }
>
> thanks,
> -peter
>
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