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From Jens Breitenstein <mailingl...@j-b-s.de>
Subject Re: Bean handling in 1:n relationships or joins
Date Wed, 07 Dec 2011 21:01:16 GMT
Hi Rainer!

I know it's not a full blown oo mapper and that was exactly the reason 
to give empire a chance after some painful hibernate experiences in past 
projects...
What about extending the getBeansList method to pass in a list of 
classes to support an OO mapping for lets say one hierarchy?

Consider we have an entity A and B
A (name)
B (whatever1, whatever2, FK_to_A)

In case we select A.name, B.whatever1, B.whatever2 by a join it's really 
comfortable to operate on a list<object[A, B]> having all parameters 
properly filled instead of an FK which requires an additional select per 
row?
I have not digged into the sources yet but I believe its not far from 
what currently exists, or am I wrong? Maybe we can add it to a 
XMas-Wishlist??

Jens


Btw: thanks for the quick response.


Am 07.12.11 18:41, schrieb Rainer Döbele:
> Hi Jens,
>
> remember that Empire-db is not an OR-Mapper and it does nothing automatically.
> In exchange it gives you more control over what, when and how database operations are
performed.
>
> Even though beans can be used as data containers, they will not provide the same level
of functinality than a DBRecord does.
>
> Again I recommend to take a look at our examples empire-db-example-basic and empire-db-example-advanced.
> Regards
>
> Rainer
>
>
>> from: Jens Breitenstein [mailto:mailinglist@j-b-s.de]
>> to: empire-db-user@incubator.apache.org
>> re: Bean handling in 1:n relationships or joins
>>
>> Hi all!
>>
>> I have to admit I am pretty new to empire-db but feel quite confortable
>> with it...
>> Finally I got the Bean mapping working for single tables and I now get
>> stuck in how to handle joins correctly...
>>
>> Assume a simple relationship between a document and a user (where the
>> users-pk is part of the documents as fk to indicate a relation
>> "document
>> is owned by user").
>> Using the getBeanList method it seems only possible to convert a "root"
>> element (in my case the document) but not any referenced element
>> automatically?
>> If I am wrong can someone explain me how I can retrieve a "document"
>> having a fully instantiated "user" element instead of just an FK?
>> Or do I have to read the user record manually and the bean handling
>> does
>> not support joined objects at all?
>>
>> thanks in advance
>>
>> Jens


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