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From Andrus Adamchik <>
Subject Re: Modification and deletion of data objects
Date Thu, 23 Jul 2009 07:24:09 GMT

On Jul 23, 2009, at 7:40 AM, sridhar devatha wrote:

> Please answer about not providing methods for getting the existing
> registered objects from data context?

You can lookup an object by ObjectId (PK, but you can define a PK more  
broadly to include any set of unique columns if you care). Or run a  
query against those same columns with a cache strategy of LOCAL_CACHE,  
which will do what you asked for - fetch only if an object is not  
already in the DataContext.

> Please answer how objectForQuery() works?That is, whether it looks  
> in the
> data context before hitting the database
> .

See above. It depends on the query cache settings.

> Please answer about declarative transactions using a good example.

Cayenne is not a J2EE container or an EJB engine. It just works in  
whatever environment you have. It's up to you to setup declarative  
transactions as appropriate in your situation. All you need to do in  
Cayenne is check "Container Managed Transactions" checkbox for the  
DataDomain to make it behave nicely in a managed environment.


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