Rails - May 2009 - how does form_for and validate_presence_of work hand in hand

when we have validate_presence_of :name in the model and then when we
put in the create action that we re-render ''new'', then the
form_for will
populate the fields, and error_messages_for ''story'' will have
the
correct error message.

this is really great, and and the same time, this looks like magic... i
found that many books don''t explain how the magic occur.  is it by some
global variable?

when the form_for is called... is it using the @story that came back
from the @story.save, instead of the  @story = Story.new  from the new
action?

sometimes i feel that i am playing magic when using Ruby on Rails,
except I don''t know how the magic happens...  kind of like if I make
the
rabbit appear, but I don''t know how I did it.  So I really want to know
the inner workings of Rails.
-- 
Posted via http://www.ruby-forum.com/.

On May 26, 5:24 am, SpringFlowers AutumnMoon <rails-mailing-
l...-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org> wrote:
>
> this is really great, and and the same time, this looks like magic... i
> found that many books don''t explain how the magic occur.  is it by
some
> global variable?
>
> when the form_for is called... is it using the @story that came back
> from the @story.save, instead of the  @story = Story.new  from the new
> action?
You render the new template, but you don''t run the new action again:
the @story you display is indeed the one that you tried to save.

Fred
>
> sometimes i feel that i am playing magic when using Ruby on Rails,
> except I don''t know how the magic happens...  kind of like if I
make the
> rabbit appear, but I don''t know how I did it.  So I really want to
know
> the inner workings of Rails.
> --
> Posted viahttp://www.ruby-forum.com/.