[Cayenne-user] Object migrates between DataDomains

Technically DataObject belongs to a DataContext, so we should be
speaking about moving objects between DataContexts (that in turn can
belong to different DataDomains). This is done with
DataContext.localObject(..)

http://objectstyle.org/confluence/display/CAYDOC/Moving+Objects
+Between+Contexts

Of course object mappings have to be compatible in both domains
involved.

Andrus

Hi,

Thank you for help. I make the changes as you say but I observe the DataContext.localObject(..) not set the relations (forign key id's).Can you help me for migrating
objects with its relations through DataDomains.

----- Orjinal Mesaj -----
Kimden: Andrus Adamchik <[email protected]>
Tarih: Monday, April 10, 2006 11:55
Konu: Re: Object migrates between DataDomains
Kime: [email protected]

Yeah, default mechanism is "lazy" in that it assumes that related
objects can be resolved from the database on demand. Copying a
subgraph of new objects is a bit more tricky. In 1.2 you can try
using org.objectstyle.cayenne.util.DeepMergeOperation for your
purpose. Something like this:

DataContext srcContext, targetContext;
DataObject object;

ClassDescriptor descriptor =
targetContext.getEntityResolver().getClassDescriptor("MyEntity");

DataObject anotherObject = new DeepMergeOperation(targetContext).merge
(object, descriptor);

DeepMergeOperation merges everything that is attached to a given
object and is already resolved in memory. If you need to implement
different logic, you can write your own version using
DeepMergeOperation as a template. An example of a different graph
traversal termination logic is ObjectDetachOperation that is based on
a preset tree of relationships.

Andrus

Hi Andrus ,

I tested DeepMergeOperation. Merged object on targetContext (anotherObject) is created as I desired with its relations but I observe actually anotherObject is not created physically on database .I used the targetContext.commitChanges() to create on database but not create it.What is the reason of this or how can commit created anotherObject on targetContext.


----- Orjinal Mesaj -----
Kimden: Andrus Adamchik
Tarih: Tuesday, April 11, 2006 17:53
Konu: Re: Object migrates between DataDomains
Kime: [email protected]

Can you explain what are you trying to achieve in general (i.e.
scenario details)? I may be able to help then.

Andrus

I want to distribute some entities from one dataDomain to another actually one database to identical other databases when a user insert,delete and update operations on these entities.To achieve this I create a superclass of object entities and I enforce the commit operation from this superclass to distribute the changes other contexts.Also I want to set this objects with relations and same primary keys on databases.
----------
For insert : runs correctly without setting relations
DataContext ctx = controllerContexts.get(domainName);
DataObject dataObj = ctx.createAndRegisterNewObject(obj.getClass());
ctx.localObject(dataObj.getObjectId(),obj);
dataObj.setObjectId(obj.getObjectId());
ctx.commitChanges();
----------
For delete: runs correctly
DataContext ctx = controllerContexts.get(domainName);
DataObject dataObj = DataObjectUtils.objectForPK(ctx,obj.getObjectId());
ctx.deleteObject(dataObj);
ctx.commitChanges();
--------
For update:???
ClassDescriptor descriptor =
localContext.getEntityResolver().getClassDescriptor(obj.getClass().getSimpleName());
System.err.println(new DeepMergeOperation(ctx).merge(obj, descriptor));
ctx.commitChanges();
--------



----- Orjinal Mesaj -----
Kimden: Andrus Adamchik
Tarih: Wednesday, April 12, 2006 11:10
Konu: Re: Object migrates between DataDomains
Kime: [email protected]

Ok, so you have something akin to a replication mechanism. Let's try
putting the new 1.2 DataChannel API to work. This is an unforeseen
use of such API, but looks like it might work and actually allow you
to synchronize all changes of the entire context at once (instead of
object by object). I have no time right now to test a fully working
example (and the API is new so there is no docs yet), but let me
outline the possible approach.

* Get the latest Cayenne nightly build (it fixes some DataChannel
event bugs).

* On commit DataContext (which is itself a DataChannel) broadcasts
two GraphEvents - one that contains committed context changes and
another one with generated PK (all changes are represented as
GraphDiff instances). See 'DataContext.flushToParent(..)' for details
on how the events are sent.

* You can register your own listener for the *source* DataContext
(look at DataContext.setChannel(..) on how to register a listener)
and apply the first group of changes to the *target* DataContext via
DataContext.onSync(..):

GraphEvent e;

// first type of event
if(e.getSource() == sourceContext && e.getPostedBy() == sourceContext) {
targetContext.onSync(sourceContext, e.getDiff(),
DataChannel.FLUSH_NOCASCADE_SYNC);
}

* Applying PK changes is less trivial, as onSync won't work...
Probably you'll have to repost this event on behalf of
targetContext's channel so that target context catches it and updates
itself accordingly.

// second type of event with PKs
else if(e.getSource() == sourceContext && e.getPostedBy() ==
sourceContext.getChannel()) {
???
}


Andrus

Hi,

I have some problems. I download the cayenne-1.2-dev-2006-4-12.tar as you said. I use the your definitions but targetContext.onSync throws below exception when localContext.commitChanges().
[email protected]
org.objectstyle.cayenne.property.PropertyAccessException: [v.1.2-dev-2006-4-12 April 12 2006] Error reading DataObject property: name
at org.objectstyle.cayenne.property.DataObjectAccessor.readPropertyDirectly(DataObjectAccessor.java:98)
at org.objectstyle.cayenne.property.SimpleProperty.readPropertyDirectly(SimpleProperty.java:110)
at org.objectstyle.cayenne.property.SimpleProperty.readProperty(SimpleProperty.java:81)
at org.objectstyle.cayenne.access.ObjectDiff$4.visitProperty(ObjectDiff.java:210)
at org.objectstyle.cayenne.property.SimpleProperty.visit(SimpleProperty.java:94)
at org.objectstyle.cayenne.property.BaseClassDescriptor.visitProperties(BaseClassDescriptor.java:247)
at org.objectstyle.cayenne.access.ObjectDiff.applySimplePropertyChanges(ObjectDiff.java:206)
at org.objectstyle.cayenne.access.ObjectDiff.access$100(ObjectDiff.java:28)
at org.objectstyle.cayenne.access.ObjectDiff$2.apply(ObjectDiff.java:105)
at org.objectstyle.cayenne.graph.CompoundDiff.apply(CompoundDiff.java:133)
at org.objectstyle.cayenne.access.ObjectStoreGraphDiff.apply(ObjectStoreGraphDiff.java:151)
at org.objectstyle.cayenne.access.DataContext.onContextFlush(DataContext.java:1171)
at org.objectstyle.cayenne.access.DataContext.onSync(DataContext.java:1148)
at tr.com.htr.hgys.db.base.DataListener.graphFlushed(DataListener.java:66)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.objectstyle.cayenne.util.Invocation.fire(Invocation.java:240)
at org.objectstyle.cayenne.event.EventManager$Dispatch.fire(EventManager.java:433)
at org.objectstyle.cayenne.event.DispatchQueue.dispatchEvent(DispatchQueue.java:182)
at org.objectstyle.cayenne.event.DispatchQueue.dispatchEvent(DispatchQueue.java:94)
at org.objectstyle.cayenne.event.EventManager.dispatchEvent(EventManager.java:372)
at org.objectstyle.cayenne.event.EventManager.postEvent(EventManager.java:343)
at org.objectstyle.cayenne.access.DataContext.fireDataChannelCommitted(DataContext.java:1616)
at org.objectstyle.cayenne.access.DataContext.flushToParent(DataContext.java:1225)
at org.objectstyle.cayenne.access.DataContext.commitChanges(DataContext.java:1121)
at tr.com.htr.hgys.db.base.DbObject.commitChanges(DbObject.java:246)
at tr.com.htr.hgys.db.Title.setTitle(Title.java:101)


----- Orjinal Mesaj -----
Kimden: Andrus Adamchik
Tarih: Wednesday, April 12, 2006 13:23
Konu: Re: Object migrates between DataDomains
Kime: [email protected]

At this point to be able to help you I'd have to actually write a
test app that does what you are doing, and perform some debugging.
Unfortunately I can't do it right now, as this functionality is kind
of a byproduct of other features (so it doesn't yet look like a
Cayenne bug to me), and I have to work on other things.

I guess you'll have to poke around on your own. If you find more
specific problems in the process, please let us know - maybe we can
fix them, but I can't investigate this right now, sorry.

Andrus

Thank you Andrus, I let you know If I find more specific problems in the process

----- Orjinal Mesaj -----
Kimden: Andrus Adamchik
Tarih: Thursday, April 13, 2006 14:05
Konu: Re: Object migrates between DataDomains
Kime: [email protected]