2012/5/9 James B. Byrne <[email protected]>:
>
> On Wed, May 9, 2012 14:55, Maurizio Casimirri wrote:
>
>>
>> The only case in which the generator fails to generate is when the
>> state of the database is not updated respect to migrations, but no
>> problem arises if we use two different models refering to same table,
>> only the differences will be taken into account. Was this your
>> question?
>
> My observation is that responsibility for the persistence layer may
> lie entirely outside the scope of projects that use an ORM of any
> description.  Making the ORM responsible for defining the persistence
> layer in this case is worse than useless; it is dangerous.
>
> Many projects leave database issues entirely in the hands of
> specialists who have their own tools to design and implement data
> structures.  The current design of RoR handles this situation since it
> presents migrations/DDL as a standalone and dispensable feature. Used
> when needed and ignored when not.
>
> I believe this is as it should be. Creating a database structure has
> nothing at all to do with programming access to it.  Likewise,
> programming access to a persistence layer is simply dependent upon
> what already exists.  Coupling these two separate functions will not
> be a happy marriage to my mind.
>
> If you wish to be able to query a model to find out exactly what
> attributes it considers as relevant would it not be best to simply
> adopt a convention and provide a well known method name to return a
> string of attributes?  Then designers can add that method and populate
> its return value in their models or not as they see fit.  If the
> convention is followed then I believe you will obtain what you desire
> without affecting anything else.  If the convention is not followed
> then that pretty much makes the argument that any other approach to
> provide the same information will not be valued as well.
>
>
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This is a good argument. The generator was to me a way to prove the
benefits of having properties declared within models, i believed it
was generally agreeable as a point of strength but obviously it is
not. It also leverage on the coupling (even if weak) between ORM and
persistence while I'm trying to argue to the contrary: i wish to see
in ruby on rails a level of abstraction between database columns and
model properties in a way that    client code (eg Paperclip) can
interact with different ORMs in the same way.

What is your opinion about that?

Regards
Maurizio

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