Re: [OJB-developers] query based on example object

[Thomas M. <tho...@ho...>]

Hi Jakob,

This looks like a useful feature!
When I first implemented QueryByExample (QBE) I did only implement a 
primary key based version.

I did not implement a generic solution as I found some difficulties.
Imagine, you don't call example.setTest(11);

The respective attribute will then be == 0;

How can we distinguish such an "un-willed" zero from a "willed"
example.setTest(0);


There are similar problems for null String attributes.

Did you address these problems in your solution?

cu,

Thomas




Jakob Braeuchi wrote:

> hi ,
> 
> i just comitted a small feature to the cvs: building a QueryByCriteria based
> on an example object.
> 
> Person example = new Person();
> Query query;
> 
> example.setBoss(false);
> example.setTest(11);
> example.setName("Br%");
> query = new QueryByCriteria(example);
> 
> this will build a QueryByCriteria with the following criteria:
> boss = false AND test=11 AND name like "Br%"
> 
> i didn't want to change the class QueryByExample nor the method
> newQuery(Object obj) of class QueryFactory because
> QueryByExample uses the Identity to retrieve Objects. Actually
> QueryByExample could be renamed QueryByIdentity...
> 
> jakob
> 
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