Re: DataContext synchronization bug ?

From: Marcin Skladaniec (marci..sh.com.au)
Date: Mon Aug 28 2006 - 21:13:06 EDT

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    Hi
    I'm not using localObject with prototype at the moment. I had some
    problems with it as well.
    Please try after doing localObject retouching some attribute, like
    dataObjectInContext2.setName(getName()), commit and see if this will
    put to the database only the new name.

    Marcin

    On 29/08/2006, at 10:53 AM, Jonathan Bélisle wrote:

    > Hi,
    >
    > It should work but it does not.
    >
    > context2.commitChanges() won't send an update statement to the
    > database if the object was modified in context1.
    >
    > I think it's not working because context2 was not notified of the
    > changes made to dataObject while it was in context1.
    >
    > Is it working for you ?
    > Try the code from the previous post. You will see that nothing gets
    > written to the database on commit.
    > If it does well..... there's something wrong somewhere :)
    >
    > Jonathan
    >
    >
    > Marcin Skladaniec wrote:
    >> Hello !
    >>
    >> I think you have it all right, but just in case:
    >> dataObjectInContext2= context2.localObject
    >> (dataObjectInContext1.getObjectId(), dataObjectInContext1);
    >> dataObjectInContext2.setPersistenceState
    >> (dataObjectInContext1.getPersistenceState() ); //In case that the
    >> object 1 state is NEW
    >> context2.commitChanges();
    >> Is it that dead simple or you are doing some more things ?
    >> I don't see a reason why it is not working for you.
    >> Marcin
    >>
    >>
    >> On 29/08/2006, at 4:49 AM, Jonathan Bélisle wrote:
    >>
    >>> Hi Marcin,
    >>>
    >>> I've already looked at localObject() and it's not good.
    >>> Here's why ?
    >>>
    >>> You have a data object : dataObjectInContext1
    >>> You modify a property : dataObjectInContext1.setName("the new
    >>> name");
    >>> You copy it to the second dataContext and modify it's
    >>> persistenceState
    >>>
    >>> dataObjectInContext2= context2.localObject
    >>> (dataObjectInContext1.getObjectId(), dataObjectInContext1);
    >>> dataObjectInContext2.setPersistenceState
    >>> (PersistenceState.MODIFIED);
    >>>
    >>> Everything is ok till now but here is the problem :
    >>>
    >>> dataObjectInContext2.commitChanges();
    >>>
    >>> Nothing will be written to the database because context2 did not
    >>> track changes of dataObjectInContext2.
    >>> That's why i'm not using localObject().
    >>> Is there a way that dataObjectInContext2 will be committed using
    >>> localObject() ?
    >>>
    >>> I'm using Cayenne 1.2
    >>>
    >>> Jonathan.
    >>>
    >>>
    >>> Marcin Skladaniec wrote:
    >>>> 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 Bélisle 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
    >>>>
    >>>>
    >>>>
    >>>>
    >>>>
    >>>>
    >>>>
    >>>
    >>
    >> -------------------------->
    >> ish
    >> http://www.ish.com.au
    >> Level 1, 30 Wilson Street Newtown 2042 Australia
    >> phone +61 2 9550 5001 fax +61 2 9550 4001
    >>
    >>
    >>
    >>
    >>
    >

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



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