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From Andrus Adamchik <and...@objectstyle.org>
Subject Re: Automatically aligning ObjectContexts when establishing a relationship
Date Mon, 19 Dec 2016 12:06:37 GMT
Yes, exactly. When your "editing" contexts are narrowly scoped, you have to transfer objects
all the time.

And now I am also dealing with an issue of framework support (Tapestry specifically). A master
object on an editor page lives in a page-scoped context. Master's to-one relationships are
modified via a dropdown (<t:select value="mainObject.rel"/>). So setters are called
by Tapestry, and related objects are deserialized with Tapestry ValueEncoder, ending up in
a shared context. I have a working solution outside Cayenne (tracking my page-scoped context
via a service, and making it accessible to the ValueEncoder). But hoped I could do it directly
somehow.

Andrus


> On Dec 19, 2016, at 2:55 PM, Aristedes Maniatis <ari@maniatis.org> wrote:
> 
> On 19/12/16 10:00pm, Andrus Adamchik wrote:
>> a.setB(b); 		// equivalent to a.setB(c1.localObject(b))
>> 			// i.e. we are attaching a different copy of B now.
>> 
>> b.setProp("newValue"); 	// we may not realize that we are changing the wrong copy...

>> c1.commitChanges(); 	// "b" changes are not committed. oops...
> 
> And this gets even messier if the related object is new and not yet persisted at all.
And if there are constraints.
> 
> I'm trying to imagine what sort of app hits these types of issues. Is this typically
where there is one big read-only context and then a user might modify some of those records,
so they are copied into a local read-write context for that user?
> 
> 
> Ari
> 
> 
> 
> -- 
> -------------------------->
> Aristedes Maniatis
> GPG fingerprint CBFB 84B4 738D 4E87 5E5C  5EFA EF6A 7D2E 3E49 102A


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