On Thu, Jun 20, 2013 at 6:09 AM, cristian cristian <lists / ruby-forum.com> wrote:

> Should I query the rows one by one?
> Should I query the whole table store into a hash and the loop through?
> When I fetch the row how can I get the column URL?

I would suggest you read http://datamapper.org/getting-started.html
and try thinking in OO terms. The whole point of an ORM is to deal
with *objects*, not rows in a database.

------- snip ------
> int = 0
> num = 3
>
> #What to do here?
> while int<num do
>    ds = Url.get(int)
>    #ds has the first row. Now how do I get the column 'URL'?

Throw all of the above away :-)

class Site  # I'd rename your Url class
  include DataMapper::Resource
  property :id, Serial
  property :description, String
  property :url, String # url in lowercase
end

Site.all.each do |site|
   puts site.url
end

HTH,
-- 
Hassan Schroeder ------------------------ hassan.schroeder / gmail.com
http://about.me/hassanschroeder
twitter: @hassan