RoR, Judge Judy, and little old ladies

[BLS]

Andrei Alexandrescu (See Website For Email) schrieb:
> After yesterday's hubbub, Judge Judy called and punished me to read 
> about RoR, in addition to the obligatory sentence of helping a little 
> old lady cross the street five times a week.
> 
> So I went and read the nice tutorial at:
> 
> http://www.onlamp.com/pub/a/onlamp/2006/12/14/revisiting-ruby-on-rails-revisited.html 
> 
> 
> I have a couple of questions that I assume will be easy to answer by 
> anyone who actually has used RoR.
> 
> On the second page of the tutorial, the authors describe how they write 
> SQL code to create tables, and then how they invoke Ruby to parse that 
> SQL code and generate (I assume) Ruby wrappers for it.
> 
> Now consider that the database changes: new tables, new fields, 
> different types for existing fields, etc.
> 
> 1. Is now the generated Ruby code is out of sync with the database?
> 
> 2. In case it is out of sync, what is the way to bring it back in sync? 
> Manual editing of the Ruby code? Editing the SQL and then regenerating 
> the wrappers? Some automated way?
> 
> An additional question: most interesting work in databases is done 
> through views (SELECT statements) and stored procedures. Can Ruby parse 
> such stuff and generate appropriate wrappers? If so, what happens when 
> the views and stored procedures change?

In general this kind of problems are solved by
implementing the observer - observeable/subject pattern.


> 
> I'm asking these questions because I want to figure whether automating 
> the task of keeping in sync with a database, plus the additional type 
> safety and speed, are significant advantages in the Web/DB domain. In 
> such a scenario, error messages like the one in Part 2 
> (http://www.onlamp.com/pub/a/onlamp/2007/01/05/revisiting-ruby-on-rails-revisited-2.html?page=4) 
> may be avoided; the code simply fails to compile. I know of domains 
> where such advantages are very important, but I'm not sure how the 
> Web/DB domain feels about it.
> 
> 
> Andrei

Bjoern