From: Jamey Cribbs <cribbsj@...>
Date: 2005-10-24T19:30:10+09:00
Subject: Re: Madeleine, SQLite and multi-platform issues (in ruby :-)

Assaph Mehr wrote:

>Sounds like standard practice to my (inexperienced) mind. I was just
>wondering if there was something like the ActiveRecord
>#has_and_belong_to_many magic.
>
>  
>
Unfortunately, no.  That might be cool to have; I'll have to put that on 
the wishlist.  :-)

>OK, here's a specific example.:
>
>Suppose I had Foo with two fields :bar and :baz. The #kb_create had
>those as parameters and KB passed them in as needed.
>
>Now version 2 has the same class Foo, but with the fields :baz and
>:qux. I.e. one field was deleted and another was added. Their relative
>'position' in the method arguments has also changed. Now if I send my
>shiny new v2.0 to a user who has a smelly old v1 database, what will
>happen? What do I need to do to respond, recover and/or upgrade the
>existing database?
>  
>
Good question.  Let's see.  Well, since the fields are passed to 
#kb_create as positional arguments, that won't be good for the user 
still on v1.0.  So, I guess you would have to include a conversion 
script that would:

1.  #delete_table_column(:foo, :bar)
2. #add_table_column(:foo, :qux)
3. Include a new class defintion referring to :qux and not referring to 
:bar.


Jamey

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