Rails - Mar 2006 - convert string to AR class

Hi everyone,

I''m trying to convert a string passed on the command-line into an 
ActiveRecord class, so I can do something like this.

    a="SomeClass"
    a.find(:all)

where

    class SomeClass < ActiveRecord::Base
    end

This appears to work (better ways would be appreciated):

    a="SomeClass"
    b=eval a
    b.find(:all)

However I would like to make sure this is an real class first, so I 
tried this since class names are constants:

    a="SomeClass"
    Modules.constants.include?( a )

but SomeClass will not show up if it has not been used yet. So I 
switched to

    a="SomeClass"
    begin
      b=eval a
      b.class # for at least one use
    rescue
      puts "error"; exit
    end

Now I want to find out if it is derived from ActiveRecord, but can''t 
seem to figure out how. I looked at Modules#ancestors and 
Module#nesting, but this does not seem to be the right thing. Any help 
would be greatly appreciated.

Thanks,
Mat Cucuzella

-- 
Posted via http://www.ruby-forum.com/.

"SomeClass".constantize.find(:all)

--
Kent


On 3/3/06, Mat <mat1975@cox.net> wrote:
> Hi everyone,
>
> I''m trying to convert a string passed on the command-line into an
> ActiveRecord class, so I can do something like this.
>
>     a="SomeClass"
>     a.find(:all)
>
> where
>
>     class SomeClass < ActiveRecord::Base
>     end
>
> This appears to work (better ways would be appreciated):
>
>     a="SomeClass"
>     b=eval a
>     b.find(:all)
>
> However I would like to make sure this is an real class first, so I
> tried this since class names are constants:
>
>     a="SomeClass"
>     Modules.constants.include?( a )
>
> but SomeClass will not show up if it has not been used yet. So I
> switched to
>
>     a="SomeClass"
>     begin
>       b=eval a
>       b.class # for at least one use
>     rescue
>       puts "error"; exit
>     end
>
> Now I want to find out if it is derived from ActiveRecord, but
can''t
> seem to figure out how. I looked at Modules#ancestors and
> Module#nesting, but this does not seem to be the right thing. Any help
> would be greatly appreciated.
>
> Thanks,
> Mat Cucuzella
>
> --
> Posted via http://www.ruby-forum.com/.
> _______________________________________________
> Rails mailing list
> Rails@lists.rubyonrails.org
> http://lists.rubyonrails.org/mailman/listinfo/rails
>

Kent Sibilev wrote:
> "SomeClass".constantize.find(:all)
That''s it! And after the following code does correctly check for
derived
from AR

    a="SomeClass".constantize
    a.ancestors.include? ActiveRecord::Base

Thanks for your help.
Mat Cucuzella

-- 
Posted via http://www.ruby-forum.com/.