> -- keith Pope <mute.pop3@googlemail.com> wrote
> (on Thursday, 11 June 2009, 07:28 AM +0100):
>> 2009/6/10 Fábio Locatelli <flocatelli@gmail.com>:
>> > I am new on this list. I am enjoying it so far.
>> >
>> > I was passing by the official Zend Quick start to see whats new and I liked
>> > the idea of Data Mapper introduced by Ralph Schindler. Ralph made a good
>> > job introducing this pattern for new users. I confess I was expecting
>> > ZF would implement this.
>
> Just for the record... I was the one who rewrote the quick start to add
> the Data Mapper during this iteration -- though I had Ralph review it
> before we posted it. It's an idea the two of us have discussed to some
> length in the past.
>
>> > I found another good article at google,
>> > http://blog.tekerson.com/2008/12/17/data-mapper-pattern-in-php and
>> > http://akrabat.com/2008/12/13/on-models-in-a-zend-framework-application/
>> >
>> > I thought data mapper very interesting I intend to include it at our next
>> > projects.
>> >
>> > Anyway! Does someone have implement data mapper as a abstract or generic
>> > class and wants to share?
>>
>> A data mapper is actually quite complex to implement properly,
>> generally it is used along side the Domain Model pattern, which again
>> is very hard to implement correctly, you may want to look at the data
>> mapper proposal on the wiki
>>
>> http://framework.zend.com/wiki/display/ZFPROP/Zend_Db_Mapper+-+Benjamin+Eberlei
>>
>> As you can see when creating/using a data mapper there are many issues
>> that need to be dealt with such as the object life cycle etc.
>
> Actually, data mappers and domain models can be trivially simple or
> tremendously complex -- the difficulty will depend on the complexity of
> your models and/or persistence layer.
>
> Domain models are simply classes -- you are defining metadata and/or
> behavior. Data mappers are used to map the model to a stateful layer
> (since PHP is stateless, this layer is necessary if you wish to persist
> the data for later retrieval). If you have a single model hitting a
> single table, it can be incredibly simple. However, when you start
> looking at 1:N and N:N relationships, they can become much more complex.
> They are not impossible for the average developer to create -- but
> they're not exactly trivial, either. Generic implementations are
> incredibly hard to get right, however, and many would argue that generic
> implementations become too cumbersome to be worth while.
This is sort of the problem I have with the quickstart, I think it
should mention the potential hurdles you will face as you start to
introduce relationships. Maybe having some links to resources about
the subject too.
>
>> If you are really interested in this subject I suggest reading martin
>> fowlers patterns of enterprise architecture book and domain driven
>> design by eric evans...
>
> I'll second those recommendations.
>
> --
> Matthew Weier O'Phinney
> Project Lead | matthew@zend.com
> Zend Framework | http://framework.zend.com/
>
>
--
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[MuTe]
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