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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