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List:       ojb-user
Subject:    Re: Help to locate and update a collection member (big collection)
From:       "Stijn de Witt" <Stijn.deWitt () bergland-it ! nl>
Date:       2004-04-29 11:01:38
Message-ID: 006e01c42dd9$587e93a0$6502a8c0 () storm
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Hi Gustavo,

Not really an answer to your question, but you may want to have a look at
OJB proxies. Auto-retrieving/updating/deleting a collection with so many
objects could become very 'expensive'.

-Stijn


----- Original Message ----- 
From: <gfaerman@fys.com.ar>
To: "OJB Users List" <ojb-user@db.apache.org>
Sent: Wednesday, April 28, 2004 7:29 PM
Subject: Help to locate and update a collection member (big collection)


> Dumb problem, but we've get some confusion here.
>
> Let's say we have a Master object that has a Details object collection.
> Details collection is a 10ths thousand objects set.
> Repository settings for Master object are autoupdate true, autoretrieve
> true,autodelete true. API is PB.
>
> Our user need to query for one specific Master object (no problem with
> this using Query object), change some attributes, then browse (paging)
> through the thousand Detail objects, until he founds the one he is looking
> for, to update some attributes in it - remember the Detail object-  (let's
> say an iterator will do this fine) . We do not have any problems on the UI
> side.
>
> The client app returns the data modified by the user (the Master object
> data and the Detail object data).
>
> Back in the server, doubts start again.
> Question here is, which is the right way to persist the changes to the DB?
>
> Pseudo code seems to be:
> 1. Retrieve Master Object.
> 2. Update some attributes
> 3. Retrieve Detail object from the Master Object collection *
> 4. Update some Detail attributes
> 5. store de Master Object.
>
> We find easy to retrieve the Master Object, but we do not see the proper
> way to retrieve and update the Detail object in the collection
> autoretrieved by the Master object.
> * How should we look for the Detail object? And then, how should we update
> an individual in a big autoretrieved collection?
> The mechanism available to retrieve certain object within PBAPI is the
> Query Object, but we do no see any OJB based methods to find an object in
> a autoretrieved collection.
> This means we should query the Detail object outside the collection (I
> mean find the single Detail object in the DB using a Query object ) In
> this case, once we get the reference to this object and we persist it back
> (the Detail object), the in-memory collection retrieved by the Master
> object will be updated?
> What if the association between Master an Detail, from a business
> perspective is a compound association? The Detail may exist or not, but
> when yes, it does so allways "compunding" a Master object, which means we
> should add him to the collection letting OJB handle the persistence
> directly?
>
> Some code snippet might enlighten us
> Thanks in advance,
> Gustavo.
>
>


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