Re: [Hibernate] Hibernate vs. Castor example

[David M. J. <dav...@nc...>]

I  tried adding the cascade="delete" attribute that you mentioned and 
the parent.getChildren().add(child) idiom, but when I did I got some 
strange behavior.  When the removeObject(feed) call was made, the 
Newsfeed was deleted by the Items that refer to the feed were not 
deleted.  Instead, all of the items had their newsfeed_id fields cleared.

I'm on MySQL, does cascading delete work on MySQL?

- Dave



Gavin King wrote:

>Looking over the source, I'm wondering about a comment in HibeAggregatorDAO
>
>        // if cascade worked, we could just do this
>        //removeObject(feed);
>
>this is followed by:
>
>ses.delete( "select newsfeed.subscriptions.elements "
>                +"from newsfeed in class ag.Newsfeed" )
>
>which should be
>
>ses.delete( "select newsfeed.subscriptions.elements "
>                +"from newsfeed in class ag.Newsfeed "
>                +"where newsfeed = ?",
>                 feed, Hibernate.association(feed) );
>
>but you wouldn't need that whole line if you had:
>
>  <set role="subscriptions" table="subscription" cascade="delete">
>   <key column="newsfeed_id" length="32" />
>   <one-to-many class="ag.Subscription" />
>  </set>
>
>in the mapping......
>
>
>P.S. I'm not keen on the way you add items to bidirectional association. The
>correct idiom is:
>
>parent.getChildren().add(child); //yes, even if the children collection is
>readonly="true"
>child.setParent(parent);
>sess.save(child);
>
>omitting the first line could cause bugs in more complicated circumstances.
>
>----- Original Message -----
>From: "David M. Johnson" <dav...@nc...>
>To: <hib...@li...>
>Sent: Sunday, December 01, 2002 1:29 AM
>Subject: [Hibernate] Hibernate vs. Castor example
>
>
>  
>
>>I've written a simple example application that shows how
>>to create a simple web application (a newsfeed aggregator)
>>with a pluggable persistence layer. I used the tried
>>and true DAO pattern to hide the database access
>>mechanism from the rest of the application.
>>I implemented the DAO interface with both Hibernate
>>and Castor.
>>
>>I did this to learn:
>>
>>- What are the drawbacks of hiding powerful persistence
>>engine behind a simple DAO interface. What do you loose?
>>Will long transaction support work? What about lazy loading?
>>
>>- What are the differences between and strenghts/weaknesses
>>of Castor and Hibernate?
>>
>>- What is the best way to implement DAO with each of
>>the tools.
>>
>>The code is very simple and (I hope) easy to follow,
>>so if you have a chance please take a look. Look at the
>>HibeAggregatorDAO and CastorAggregatorDAO implementations
>>to see how I used Hiberate and Castor to implement the
>>very same DAO. I'd love to get your opinions on the
>>above topics.
>>
>>The readme is here:
>>http://sourceforge.net/project/shownotes.php?release_id=125110
>>
>>The download is here:
>>http://sourceforge.net/project/showfiles.php?group_id=47722
>>
>>
>>Thanks,
>>- Dave
>>
>>http://www.rollerweblogger.org/page/roller
>>
>>
>>
>>
>>
>>
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>
>
>  
>