Re: [ojb-users] Storing mapped objects
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Re: [ojb-users] Storing mapped objects
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From: Thomas M. <tho...@ho...> - 2002-05-31 09:39:01
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Hi all
Govindarajan S (Gover) wrote:
> HI,
> Thanx for yr answer. While working through the tutorial:3 i found an
> addition to the repository.xml which would do this persistence by
> reachability.
> <auto.retrieve>true</auto.retrieve>
> <auto.update>false</auto.update>
> <auto.delete>false</auto.delete>
> Adding the above set of elements to your mapping would persist all dependent
> objects aswell.
>
The OJB PersistenceBroker also provides persistence by reachability, sure.
but use this feature in the PB API you'll have to change the above
mentioned flags to
<auto.retrieve>true</auto.retrieve>
<auto.update>true</auto.update>
<auto.delete>true</auto.delete>
> I agree with your second observation aswell. Since there isnt a direct
> mapping of the roles table in case of non-decomposed mapping, there are
> cases when your mapping table is filled partially. Take the case of
> PERSON_PROJECT, which has the
> * PERSON_ID
> * PROJECT_ID
> * ROLE_NAME
> With the non-decomposed mapping where u have mapped only the PERSON_ID and
> PROJECT_ID in the ClassDescriptor mapping for PERSON and PROJECT when we try
> to add a person who has a project associated with him, the ROLE_NAME field
> is NULL and the Broker comes back with an error message as below,
>
> [DEFAULT] ERROR: 1,
> Acme,
> Acme Systems Inc.,
> int,
> java.lang.String,
> java.lang.String,
>
> this would probably have a wider implication.
>
> I havent looked at fully the ODMG spec, maybe that can help here.
>
> gover
>
> -----Original Message-----
> From: Domagoj Jugovic [mailto:do...@la...]
> Sent: Wednesday, May 29, 2002 7:16 PM
> To: Govindarajan R S
> Subject: Re: [ojb-users] Storing mapped objects
>
>
> As I red the tutorials only ODMG implementation supports "persistence by
> reachability" , so try with ODMG api.
>
That's not true! (see my statement above)
> This leaves one question , OK, it's no problem to save the objects manualy,
> but how to save data in "association table" in non-decomposed m:n mapping
> (tutorial3 - Support for non-decomposed . . . .).
OJB is doing this for you ! There are several testcases proving that
this works!
> In this case there is no concrete mapping for the "association table", so
> OJB could only update that table by looking at new objects in Collection
> specified by CollectionDescriptor.
That's exactly what happens internally!
> But if OJB doesn't look in that
> Collection it seems inpossible to insert data in that table without
> implicit mapping for "association table"??
Why do think OJB does not do this?
Hey, this is an *open source* project. One short look at the source code
of the respective testcases or stepping through the debugger will help
you more than all these speculations!
> Hi,
>
> I have a doubt regarding the storing of mapped objects. I tried to implement
> the 1:1 relationship between the ProductGroup and Article. Whenever i was
> setting the product instance in the article and when i persist the article
> the ProductGroup is not persisted. Look at the code below,
>
> Article article = new Article();
> article.setArticleName ("TestArticle");
>
> ProductGroup prodGrp = new ProductGroup();
> prodGrp.setProdGroupName("Group1");
> prodGrp.setDescription ("Testgroup");
>
> article.setProductGroup (prodGrp);
> try {
> broker.beginTransaction();
> broker.store(article);
> broker.commitTransaction();
> } catch (PersistenceBrokerException pExp) {
> System.out.println ("----- Error persisting Article -----");
> pExp.printStackTrace();
> } // end of try-catch
>
> There are two tables namely the ProductGroup and Article. And the mapping is
> all done as per the tutorial:3.
>
> With the above code, i expected the ProductGroup to be saved as well. But i
> had to persist the ProductGroup object ('prodGrp') separately. Is this a bug
> or iam missing out a funda here?
>
> This was the case with the 1:n mapping as well.
you'll have to set <auto.update>true</auto.update> on the respective
Reference- and CollectionDescriptors.
It's explained here:
http://objectbridge.sourceforge.net/tutorial3.html#cascading
Again there is no need for "doubts". All those features are regression
tested.
HTH,
Thomas
>
> I retrieve the ProductGroup and add articles to it. But i persist the
> ProductGroup hoping that the objects in the collection are also persisted.
> But i dont find the articles persisted. Code is below,
>
> Criteria qryCriteria = new Criteria();
> qryCriteria.addEqualTo ("prodGroupName","Grocery");
> QueryByCriteria criterion = new QueryByCriteria (ProductGroup.class,
> qryCriteria);
> ProductGroup prodGroup = (ProductGroup)broker.
> getObjectByQuery(criterion);
> Article art1 = new Article();
> art1.setArticleName ("Tea");
> art1.setProductGroup (prodGroup);
>
> Article art2 = new Article();
> art2.setArticleName ("Coffee");
> art2.setProductGroup (prodGroup);
>
> prodGroup.addArticle (art1);
> prodGroup.addArticle (art2);
>
> try {
> broker.beginTransaction();
> broker.store(prodGroup);
> broker.commitTransaction();
> System.out.println("--- Added the articles ---");
>
> } catch (PersistenceBrokerException pExp) {
> System.out.println("---- Error storing 1:n relation objs ---");
> pExp.printStackTrace();
> } // end of try-catch
>
> any help in this regard would be greatly appreciated
>
> regds
>
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