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From Jakob Braeuchi <jbraeu...@gmx.ch>
Subject Re: Proposal to get rid of ojbConcreteClass
Date Sat, 07 Aug 2004 13:19:22 GMT
hi charles,

it is my intention to keep things as backward compatible as possible.
when reading the repository.xml i'll build a selector when i find a 
field-descriptor with the magic name 'ojbConcreteClass'. the selector will point 
to thes field-descriptor and the value will be the name of the class.

jakob

Charles Anthony schrieb:

> For What It's Work - So long as we can retain the current ojbConcreteClass
> behaviour (by including the same old field-descriptor, pointing a new
> concrete-selector at it, and defaulting the value to the classname), I have
> no objections and it seems to be a good idea. 
> 
> Cheers,
> 
> Charles.
> 
> 
>>-----Original Message-----
>>From: Jakob Braeuchi [mailto:jbraeuchi@gmx.ch]
>>Sent: 07 August 2004 13:24
>>To: OJB Developers List; Armin Waibel; Andrew.Clute@osn.state.oh.us
>>Subject: Proposal to get rid of ojbConcreteClass
>>
>>
>>hi all,
>>
>>i think we need a more flexible approach when mapping 
>>multiple classes to one 
>>single table. today we have the field-descriptor 
>>'ojbConcreteClass', a working 
>>solution i have to admit.
>>the biggest problem is imo that we always store the name of 
>>the class in the 
>>database. this makes refactoring of the package structure 
>>unnecessarily 
>>difficult. another, but minor issue, is that ojbConcreteClass 
>>is an ordinary 
>>field-descriptor.
>>
>>i propose to add some kind of concrete-selector to the 
>>class-descriptor. this 
>>selector points to an ordinary field-descriptor. additionaly 
>>the selector may 
>>have a value that is stored instead of the real class name. 
>>if no selector-value 
>>is defined we could still use the class name as default:
>>
>><class-descriptor
>>	class="org.apache.ojb.broker.ObjectRepository$A"
>>	table="AB_TABLE"
>>	selector-field-ref="my_conrete_class"	
>>	selector-field-value="class_a"	
>> >
>>	<field-descriptor
>>          name="id"
>>          column="ID"
>>          jdbc-type="INTEGER"
>>          primarykey="true"
>>          autoincrement="true"
>>        	/>
>>        	<field-descriptor
>>          name="my_conrete_class"
>>          column="CLASS_NAME"
>>          jdbc-type="VARCHAR"
>>        	/>
>>	...
>></class-descriptor>
>>
>>as an alternative the selector could also be defined using a 
>>special element:
>>
>><class-descriptor
>>	class="org.apache.ojb.broker.ObjectRepository$A"
>>	table="AB_TABLE"
>> >
>>	<selector-descriptor
>>	 field-ref="my_conrete_class"	
>>	 value="class_a"	
>>	/>
>>
>>	<field-descriptor
>>          name="id"
>>          column="ID"
>>          jdbc-type="INTEGER"
>>          primarykey="true"
>>          autoincrement="true"
>>        	/>
>>        	<field-descriptor
>>          name="my_conrete_class"
>>          column="CLASS_NAME"
>>          jdbc-type="VARCHAR"
>>        	/>
>>	...
>>  </class-descriptor>
>>
>>there's another proposal by andrew clute to include a 
>>class-selector in the 
>>reference-descriptor:
>>
>>http://nagoya.apache.org/eyebrowse/ReadMsg?listName=ojb-dev@db
> 
> .apache.org&msgNo=7861
> 
> actually this does not address the same problem, but we should make sure
> that 
> the naming is consistent.
> 
> what do you think ?
> 
> jakob
> 
> 
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