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From "Clinton Begin" <clinton.be...@gmail.com>
Subject Re: iBatis Book - Lazy Loading Description
Date Fri, 05 Jan 2007 04:03:42 GMT
Paul is right, but I'd like to add a little more to the explanation:

With enhancement (CGLIB) you can lazy load properties of complex, concrete
or abstract types (as well as interfaces).  Without enhancement (CGLIB), you
can only lazy load properties of interface types.

The reason is that Java's Dynamic Proxy facility only supports dynamic
implementation of interfaces.  It does not support dynamic class extension
-- which really sucks and for which there is NO good reason (as proven by
CGLIB).

So that's the story.  I hope it helps.

Clinton

On 1/4/07, MCCORMICK, Paul <Paul.McCORMICK@doir.wa.gov.au> wrote:
>
>  Setting lazyLoadingEnabled to true will allow the lazy loading 1 to many
> relationships.  You don't have any 1 to many relationships in your code
> below.
> Setting enhancementEnabled  to true will allow the lazy loading of 1 to 1
> relationships.
>
>  ------------------------------
> *From:* Kuntz, Tim [mailto:tim_kuntz@pamperedchef.com]
> *Sent:* Friday, 5 January 2007 11:24 AM
> *To:* user-java@ibatis.apache.org
> *Subject:* iBatis Book - Lazy Loading Description
>
>  The new iBatis book describes lazy-loading as follows (pg 131).
>
> "To use lazy loading, we need to edit the SqlMapConfig.xml file to enable
> it by changing the lazyLoadingEnabled attribute to true in the <setting>
> element. If you want to use the cglib enhanced version of lazy loading, you
> will want to download it, add it to your application's classpath, and change
> the enhancementEnabled attribute of the <setting> element to true as well."
>
> After setting up a sample similar to that in the book, I noticed that
> lazy-loading only appears to work correctly if BOTH lazyLoadingEnabled and
> enhancementEnabled are set to true. Running the following code executes the
> selects as the objects are requested.
>
> person = sqlMapper.queryForObject("Person.selectPerson"); // runs select
> ... from person
>
> person.getAddress(); // runs select .. from address
>
> person.getAddress().getState(); // runs select .. from state
>
> Setting enhancementEnabled to false causes all of the select statements to
> execute initially. Changing lazyLoadingEnabled to false doesn't change the
> behavior.
>
> person = sqlMapper.queryForObject("Person.selectPerson"); // runs all 3
> select statements
>
> person.getAddress();
>
> person.getAddress().getState();
>
> Is this correct behavior? If so, when would I benefit from
> lazyLoadingEnabled = "true"?
>
> I'm using iBatis version 2.3.0.677
>
> Thanks,
>
> Tim
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