# Variables output in views/layouts?

**URL:** <https://www.ruby-forum.com/t/variables-output-in-views-layouts/136765>\
**Category:** Rails\
**Created:** [May 6, 2008, 7:11am UTC](https://www.ruby-forum.com/t/variables-output-in-views-layouts/136765 "2008-05-06T07:11:18Z")\
**Posts on this page:** 9\
**Page:** 1

<div class="post-metadata">

**Author:** ![casper\_the\_ghost](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/58956e/32.png) [@casper\_the\_ghost](https://www.ruby-forum.com/u/casper_the_ghost)\
**Post date:** [May 6, 2008, 7:11am UTC](https://www.ruby-forum.com/t/variables-output-in-views-layouts/136765/1 "2008-05-06T07:11:18Z")

</div>

Hi, I usually always deal with arrays this is the first time I have to  
deal with a regular variable on a different view in this case in the  
layout… so I have in my method:  
def online  
@online = Status.count\_by\_sql “SELECT COUNT(\*) FROM status  
WHERE  
status = ‘online’;”  
end

and in my layout view I have  
\<%= @online %\>

and nothing comes up… ☹

What im doing wrong?

my question is how can I call variables from different controllers on  
different views or in my layouts…??

Thanks

---

<div class="post-metadata">

**Author:** ![casper\_the\_ghost](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/58956e/32.png) [@casper\_the\_ghost](https://www.ruby-forum.com/u/casper_the_ghost)\
**Post date:** [May 6, 2008, 7:23am UTC](https://www.ruby-forum.com/t/variables-output-in-views-layouts/136765/2 "2008-05-06T07:23:03Z")

</div>

maybe the count is zero? Have you tried printing the value to the  
log? try logger.info(“value of count: #{@count}”) in your controller  
code

and if you’re trying to display the number of users online, you might  
want to look at the session data to figure this out.

---

<div class="post-metadata">

**Author:** ![casper\_the\_ghost](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/58956e/32.png) [@casper\_the\_ghost](https://www.ruby-forum.com/u/casper_the_ghost)\
**Post date:** [May 6, 2008, 7:48am UTC](https://www.ruby-forum.com/t/variables-output-in-views-layouts/136765/3 "2008-05-06T07:48:17Z")

</div>

Mike G. wrote:

> maybe the count is zero? Have you tried printing the value to the  
> log? try logger.info(“value of count: #{@count}”) in your controller  
> code
> 
> and if you’re trying to display the number of users online, you might  
> want to look at the session data to figure this out.

Yes I have try this testing it with the view for that method…  
and no this is not for the users online but another application.  
I also have try it from the console and there works…

so I am puzzle I am searching google with no straight result…  
searching for “rails instance variables in layout”

I get a lot of how to use your view variables in layouts and viceversa  
but  
not the method variables or instance variables

---

<div class="post-metadata">

**Author:** ![casper\_the\_ghost](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/58956e/32.png) [@casper\_the\_ghost](https://www.ruby-forum.com/u/casper_the_ghost)\
**Post date:** [May 6, 2008, 8:18am UTC](https://www.ruby-forum.com/t/variables-output-in-views-layouts/136765/4 "2008-05-06T08:18:54Z")

</div>

if the @online variable contains a value, it will be printed by the  
\<%= @online %\> statement. If nothing is printed, then the variable  
contains a null value. What gets printed in your log? Try logging  
the value in your view code right before you use the \<%= @online %\>,  
such as the following:

\<% logger.info(“online contains #{@online} online.blank?  
#{@online.blank?}”) %\>  
\<%= @online %\>

if the logger prints out a value for @online, yet the second statement  
prints nothing, then something is seriously wrong with your rails  
stack

---

<div class="post-metadata">

**Author:** ![casper\_the\_ghost](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/58956e/32.png) [@casper\_the\_ghost](https://www.ruby-forum.com/u/casper_the_ghost)\
**Post date:** [May 6, 2008, 8:40am UTC](https://www.ruby-forum.com/t/variables-output-in-views-layouts/136765/5 "2008-05-06T08:40:43Z")

</div>

## Ok I added that and I get:

## Rendering pages/show online contains online.blank? true Rendered layouts/\_menu (0.00793)

it returns true…  
I know it has a value because if I go to  
[http://url.com/status/whos\_online](http://url.com/status/whos_online)  
I get the right ammount of users online…  
not if I put exacly the same variable in the layout is not showing  
anything…

also here is the console:

libre jabber # ./script/console  
Loading development environment.

> > @online = Status.count\_by\_sql “SELECT COUNT(\*) FROM status WHERE  
> > status = ‘online’;”  
> > =\> 11  
> > @online  
> > =\> 11

so this also works in the view… is obvios that in the layout there is  
nothing happening…  
do I have to tell the layout from what methong/class is the variable?

Mike G.  
escribió:\> if the @online variable contains a value, it will be printed by the

> stack
> 
> > > 
> > 
> > so I am puzzle I am searching google with no straight result…

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- Karl Marx -

---

<div class="post-metadata">

**Author:** ![casper\_the\_ghost](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/58956e/32.png) [@casper\_the\_ghost](https://www.ruby-forum.com/u/casper_the_ghost)\
**Post date:** [May 6, 2008, 8:53am UTC](https://www.ruby-forum.com/t/variables-output-in-views-layouts/136765/6 "2008-05-06T08:53:43Z")

</div>

On 5/6/08, rek2 [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote:

> ## Ok I added that and I get:
> 
> ## Rendering pages/show online contains online.blank? true Rendered layouts/\_menu (0.00793)
> 
> it returns true…

do you understand that returning true is not what you want? The line  
of code I wrote was:

\<% logger.info(“online contains #{@online} online.blank?  
#{@online.blank?}”) %\>

this prints the value of the @online ivar and it also prints whether  
or not @online is nil or blank (if it’s an empty string). In this  
case it printed “true”, which means that @online doesn’t contain what  
you think it contains. Most likely it’s nil.

> I know it has a value because if I go to [http://url.com/status/whos\_online](http://url.com/status/whos_online)  
> I get the right ammount of users online…

and what does your whos\_online method do?

> not if I put exacly the same variable in the layout is not showing  
> anything…

the @online method will only be assigned in your ‘online’ action. If  
you put:

Number of users online: \<%= @online %\> in your layout, then this will  
only contain a value if the action you’re calling assigns to the  
@online variable. Since you’re displaying this value in your layout,  
you’ll want to globally assign this value either in a before filter in  
your controller, or in your ApplicationController.

---

<div class="post-metadata">

**Author:** ![casper\_the\_ghost](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/58956e/32.png) [@casper\_the\_ghost](https://www.ruby-forum.com/u/casper_the_ghost)\
**Post date:** [May 6, 2008, 4:17pm UTC](https://www.ruby-forum.com/t/variables-output-in-views-layouts/136765/7 "2008-05-06T16:17:29Z")

</div>

> Hmm I’m confused… I though that the application layout will be used if  
> there is no default layout for  
> a method, and that instances variables from methods can be used in their  
> layouts… this is why I was hoping  
> for this to work.

You are right about the layout. The problem is that the @online is  
not being set with every method that uses the application layout. The  
purist way to solve the problem would be to create a before\_filter in  
the ApplicationController and use that filter to load the @online  
instance variable. That way it will be inherited by all your  
controllers and available to all your actions when they default into  
using the application layout.

You might also want to wrap up your lookup into a class method on the  
Status controller. It will make things more expressive when you re-  
read the code later.

class Status \< ARec::Base  
…  
def self.currently\_online  
count(:conditions=\>{:status=\>‘online’})  
end  
…  
end

If you can deal with a little impurity (mixing V/C) in your  
application layout you can also put the call to find the count in your  
template:

\<%= Status.currently\_online %\>

---

<div class="post-metadata">

**Author:** ![casper\_the\_ghost](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/58956e/32.png) [@casper\_the\_ghost](https://www.ruby-forum.com/u/casper_the_ghost)\
**Post date:** [May 6, 2008, 9:00am UTC](https://www.ruby-forum.com/t/variables-output-in-views-layouts/136765/8 "2008-05-06T09:00:15Z")

</div>

Mike G.  
escribió:\>

> 

Yes, of course, this is why I sent the console output 🙂 so the issue  
is that layout is seen the variable as nil.

> and what does your whos\_online method do?

is the method were I create the variable @online

class StatusController \< ApplicationController  
def who\_online  
@online = Status.count\_by\_sql “SELECT COUNT(\*) FROM status WHERE  
status = ‘online’;”  
end  
end

> the @online method will only be assigned in your ‘online’ action. If you put:
> 
> Number of users online: \<%= @online %\> in your layout, then this will  
> only contain a value if the action you’re calling assigns to the  
> @online variable. Since you’re displaying this value in your layout,  
> you’ll want to globally assign this value either in a before filter in  
> your controller, or in your ApplicationController.

Hmm I’m confused… I though that the application layout will be used if  
there is no default layout for  
a method, and that instances variables from methods can be used in their  
layouts… this is why I was hoping  
for this to work.

Basically the layout Im using already has data that works well with a  
render of \_menu etc… I am just trying to add  
to a corner of my site the amount of people using the service… so how  
will I go to do this? I though this was going to be easy…  
☹

Thanks.

---

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**Author:** ![casper\_the\_ghost](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/58956e/32.png) [@casper\_the\_ghost](https://www.ruby-forum.com/u/casper_the_ghost)\
**Post date:** [May 7, 2008, 4:22am UTC](https://www.ruby-forum.com/t/variables-output-in-views-layouts/136765/9 "2008-05-07T04:22:39Z")

</div>

> read the code later.  
> application layout you can also put the call to find the count in your  
> template:

Hi, I have ended moving the method to the application controller.  
Thanks!

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