Rails - Nov 2005 - Ruby for "If url contains id"

I''m trying to distinguish between a url that passes an id value such
as:
/localhost:3000/person/new/3

and one that doesn''t such as:
/localhost:3000/person/new/

Can anyone tell me what the Ruby for "If a parameter has been passed"?
Many thanks in advance!

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Is this what you''re looking for?

     doSomething if @params[:id].nil?

On 23-Nov-05, at 6:31 PM, Nick Ce wrote:
> I''m trying to distinguish between a url that passes an id value  
> such as:
> /localhost:3000/person/new/3
>
> and one that doesn''t such as:
> /localhost:3000/person/new/
>
> Can anyone tell me what the Ruby for "If a parameter has been
passed"?
> Many thanks in advance!
>
> -- 
> Posted via http://www.ruby-forum.com/.
> _______________________________________________
> Rails mailing list
> Rails-1W37MKcQCpIf0INCOvqR/iCwEArCW2h5@public.gmane.org
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>

dteare wrote:
> Is this what you''re looking for?
> 
>      doSomething if @params[:id].nil?

Thanks for the reply - that looks really promising, but I can''t quite 
get it to work. I''m writing a really simple method that I want to
behave
differently if a parameter is passed to it. At present it looks like:

  def new
    @person = Person.new
    @addedcompany = Company.find(params[:id])
  end

I only need the @addedcompany variable to be assigned if @params[:id] 
exists. So far I''ve tried this based on your suggestion but with no
joy:

  def new
    @person = Person.new
    @addedcompany = Company.find(params[:id]) if !@params[:id].nil?
  end



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this should work....I don''t believe you need the @ infront of the
params
as in your previous code

   def new
     @person = Person.new
     @addedcompany = Company.find(params[:id]) unless params[:id].nil?
   end

Cheers,
Steven

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Steven wrote:
> this should work....I don''t believe you need the @ infront of the
params
> as in your previous code
> 
>    def new
>      @person = Person.new
>      @addedcompany = Company.find(params[:id]) unless params[:id].nil?
>    end
> 
> Cheers,
> Steven

Fantastic - that''s working very well now. Thanks you both for your
help.
As an aside, would someone be kind enough to explain when the use of @ 
in front of a variable is required, and when it isn''t?

-- 
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AFAIK the @ before the variable indicates that it is an instance
variable, while @@ is used to access a class variable. I believe that
you don''t need the @ if you used attr_reader/writer.

On 11/24/05, Nick Ce <graphis1-ee4meeAH724@public.gmane.org>
wrote:
> Steven wrote:
> > this should work....I don''t believe you need the @ infront of
the params
> > as in your previous code
> >
> >    def new
> >      @person = Person.new
> >      @addedcompany = Company.find(params[:id]) unless params[:id].nil?
> >    end
> >
> > Cheers,
> > Steven
>
>
> Fantastic - that''s working very well now. Thanks you both for your
help.
> As an aside, would someone be kind enough to explain when the use of @
> in front of a variable is required, and when it isn''t?
>
> --
> Posted via http://www.ruby-forum.com/.
> _______________________________________________
> Rails mailing list
> Rails-1W37MKcQCpIf0INCOvqR/iCwEArCW2h5@public.gmane.org
> http://lists.rubyonrails.org/mailman/listinfo/rails
>

martin wrote:
> AFAIK the @ before the variable indicates that it is an instance
> variable, while @@ is used to access a class variable. I believe that
> you don''t need the @ if you used attr_reader/writer.
back in the days params was an instance variable...so i should be 
addressed as @params...now params is a method call and should be 
addressed as params...

the old way still works, but use the new method...goes for session 
too...

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Thanks for the clarification folks - that''s helped me to get my head 
round it.

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