Rails - Jun 2006 - before_filter: nil vs. true vs. false

Folks,

My understanding of how filters work is that I should return true if  
everything is ok and false if not. How does the filter below work  
then (from the Rails Recipies book)?

It would return nil if there''s a user in the session. Does nil count  
as true?

before_filter :check_authentication

def check_authentication
	unless session[:user]
		session[:intended_action] = action_name
		session[:intended_controller] = controller_name
		redirect_to :action => "signin"
	end
end

	Thanks, Joel

--
http://wagerlabs.com/

Joel Reymont wrote:
> It would return nil if there''s a user in the session. Does nil
count
> as true?

In Ruby, only false and nil are false, anything else is true

Cheers

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

On Jun 30, 2006, at 3:32 PM, Chris Hulan wrote:
> In Ruby, only false and nil are false, anything else is true
Great. So that means that the following will return false when  
there''s a user in the session and filter processing will stop (action  
will be aborted?). Isn''t this filter missing a "return true"
as its
last statement?

def check_authentication
	unless session[:user]
		session[:intended_action] = action_name
		session[:intended_controller] = controller_name
		redirect_to :action => "signin"
	end
end

--
http://wagerlabs.com/

Joel Reymont wrote:
> Great. So that means that the following will return false when
> there''s a user in the session 
"unless" evaluates an expression to true or false... so in the above
if
a user is logged in session[:user] will return true because it''s not
nil
-- it exists and is therefore not false. There''s no need for a
"return
true" because the code block won''t be executed if session[:user]
exists.

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

On Jun 30, 2006, at 3:57 PM, Guest wrote:
> "unless" evaluates an expression to true or false... so in the  
> above if
> a user is logged in session[:user] will return true because it''s  
> not nil
> -- it exists and is therefore not false. There''s no need for a
"return
> true" because the code block won''t be executed if
session[:user]
> exists.
I ran "true unless true" at the irb prompt and got nil so I assumed  
that the result of the filter would be nil so long as the unless  
block does not execute.

Are you saying that the return value will be different if the unless  
block is not triggered? What is the resulting value of the trigger then?

	Thanks, Joel

--
http://wagerlabs.com/

Joel Reymont wrote:
> Folks,
> 
> My understanding of how filters work is that I should return true if 
> everything is ok and false if not. How does the filter below work then 
> (from the Rails Recipies book)?
> 
> It would return nil if there''s a user in the session. Does nil
count as
> true?
Only returning false will halt processing. See:

http://api.rubyonrails.com/classes/ActionController/Filters/ClassMethods.html

-- 
Philip Ross
http://tzinfo.rubyforge.org/ -- DST-aware timezone library for Ruby

Thanks Philip!

On Jun 30, 2006, at 4:27 PM, Philip Ross wrote:
> Only returning false will halt processing. See:
>
> http://api.rubyonrails.com/classes/ActionController/Filters/ 
> ClassMethods.html
--
http://wagerlabs.com/

> Are you saying that the return value will be different if the unless
> block is not triggered? What is the resulting value of the trigger then?
If the unless block is executed the return value will be the value of 
the last statement.  So whatever is returned from ''redirect_to :action 
=> "signin"'' will be the returned.

Cheers

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

I meant the resulting value of the "filter" rather than
"trigger".
It''s clearly nil if unless is not executed but the filter system only  
takes action on false so it does not matter.

On Jun 30, 2006, at 6:15 PM, Chris Hulan wrote:
> If the unless block is executed the return value will be the value of
> the last statement.  So whatever is returned from ''redirect_to
:action
> => "signin"'' will be the returned.
--
http://wagerlabs.com/