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From Marcin Skladaniec <mar...@ish.com.au>
Subject Re: DataContext synchronization bug ?
Date Sun, 27 Aug 2006 22:26:19 GMT
Hello Jonathan

Please take a closer look on the localObject() method.
Straight from javadocs :
"Returns an object local to this DataContext and matching the  
ObjectId. If prototype is not null, local object is refreshed with  
the prototype values.

In case you pass a non-null second parameter, you are responsible for  
setting correct persistence state of the returned local object, as  
generally there is no way for Cayenne to determine the resulting  
local object state."

If you have still problems please mention what version of cayenne are  
you using.

Marcin
-------------------------->
ish
http://www.ish.com.au
Level 1, 30 Wilson Street Newtown 2042 Australia
phone +61 2 9550 5001   fax +61 2 9550 4001


On 28/08/2006, at 6:33 AM, Jonathan BĂ©lisle wrote:

> Hi, maybe someone can help me here.
>
> I'm trying to copy a dataObject to another dataContext while keeping
> it's modified state so that it will be correctly committed to the  
> db by the second dataContext.
>
> Let say we have an entity with an attribute Name and a relationship  
> Category.
> The object 1000001 exist in the db and has a Name and a Category
>
> //Create the dataContext
> DataContext dc1= DataContext.createDataContext();
> DataContext dc2= DataContext.createDataContext();
>
> //Get object from db. Modify the name.
> Animal from= (Animal) DataObjectUtils.objectForPK(dc1, new ObjectId 
> ("Animal", "animalId", 1000001));
> from.setName("XXX" + new SecureRandom().nextInt());
>
> //Get local object to dc2
> //I cannot use dc2.localObject(from.getObjectId(), from);
> //because the dc2 won't see the modification made in dc1.
> Animal to= (Animal) dc2.localObject(from.getObjectId(), null);
> dc2.getObjectStore().resolveHollow(to);
>
> //Copy the attributes from object1 to object2      String attName;
> ObjAttribute objAttribute;
> ObjEntity objEntity= from.getObjectContext().getEntityResolver 
> ().lookupObjEntity(to);
> Iterator attributes = objEntity.getAttributes().iterator();
> while (attributes.hasNext()) {
>    objAttribute = (ObjAttribute) attributes.next();
>    attName= objAttribute.getName();
>
>    to.writeProperty(attName, from.readPropertyDirectly(attName));
> }
>       dc2.commitChanges();
>
> System.out.println(from);
> System.out.println(to);
>
> Everything is committed correctly to the db but the object from has  
> now a Category = null
>
> The problem is after the dc2.commitChanges() and
> it comes from  
> org.objectstyle.cayenne.event.EventManager.DispatchThread.run()  
> witch is firing an event to set the relationship Category to null.
> I don't know why it is doing that.
> I am doing something wrong ? Is it a bug in cayenne ?
> And i need context synchronization so turning it off is not an option.
>
> I really need help on this one, can someone help me ?
>
> Jonathan





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