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Jeff Ward

2006-Jun-02 01:21 UTC

[Rails] Set instance variable for all actions in the Controller

Can I set an application wide instance variable that is available for all
actions...and their views?

eg.
class ApplicationController < ActionController::Base
  @current_user = User.find(session[:user_id])
end

and everywhere I can call @current_user.id and I can get that object? Even
down in the views?

I could not get this to work...

Thanks in advance,

Jeff
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dblack@wobblini.net

2006-Jun-02 01:29 UTC

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[Rails] Set instance variable for all actions in the Controller

Hi --

On Thu, 1 Jun 2006, Jeff Ward wrote:
> Can I set an application wide instance variable that is available for all
> actions...and their views?
>
> eg.
> class ApplicationController < ActionController::Base
>   @current_user = User.find(session[:user_id])
> end
>
> and everywhere I can call @current_user.id and I can get that object? Even
> down in the views?
>
> I could not get this to work...
What you''ve got there is an instance variable, but it''s an
instance
variable that belongs to the class object, ApplicationController,
itself.  Like so many things in Ruby, it comes down to: classes are
objects too :-)

What you want are instance variables that belong to the particular
instance of the controller that gets created and runs the action.  You
can do this using a before_filter hook:

   class ApplicationController < ActionController::Base
     before_filter :set_user
     def set_user
       @current_user = User.find(session[:user_id])
     end
   end

etc.  You''d probably want to limit it to certain actions, but you can
do that too.  (See API docs for before_filter and other related
methods.)

Notice that @current_user is inside an instance method definition.  So
when that code gets executed, it will be in the context of a
particular instance of ApplicationController, and that instance will
own the instance variable.

David

-- 
David A. Black (dblack@wobblini.net)
* Ruby Power and Light, LLC (http://www.rubypowerandlight.com)
   > Ruby and Rails consultancy and training
* Author of "Ruby for Rails" from Manning Publications!
   > http://www.manning.com/black

Jeff Ward

2006-Jun-02 01:41 UTC

head link

[Rails] Set instance variable for all actions in the Controller

Wow, an "a ha" moment for me. This helps out tremendously.

It shows in your response that you are an educator. I have your book and it
also has helped me fudge my way through learning Ruby.

Thank-you for writing one of the first Rails books when we are so short on
good, professional documentation.


On 6/1/06, dblack@wobblini.net <dblack@wobblini.net>
wrote:>
> Hi --
>
> On Thu, 1 Jun 2006, Jeff Ward wrote:
>
> > Can I set an application wide instance variable that is available for
> all
> > actions...and their views?
> >
> > eg.
> > class ApplicationController < ActionController::Base
> >   @current_user = User.find(session[:user_id])
> > end
> >
> > and everywhere I can call @current_user.id and I can get that object?
> Even
> > down in the views?
> >
> > I could not get this to work...
>
> What you''ve got there is an instance variable, but it''s
an instance
> variable that belongs to the class object, ApplicationController,
> itself.  Like so many things in Ruby, it comes down to: classes are
> objects too :-)
>
> What you want are instance variables that belong to the particular
> instance of the controller that gets created and runs the action.  You
> can do this using a before_filter hook:
>
>    class ApplicationController < ActionController::Base
>      before_filter :set_user
>      def set_user
>        @current_user = User.find(session[:user_id])
>      end
>    end
>
> etc.  You''d probably want to limit it to certain actions, but you
can
> do that too.  (See API docs for before_filter and other related
> methods.)
>
> Notice that @current_user is inside an instance method definition.  So
> when that code gets executed, it will be in the context of a
> particular instance of ApplicationController, and that instance will
> own the instance variable.
>
>
> David
>
> --
> David A. Black (dblack@wobblini.net)
> * Ruby Power and Light, LLC (http://www.rubypowerandlight.com)
>    > Ruby and Rails consultancy and training
> * Author of "Ruby for Rails" from Manning Publications!
>    > http://www.manning.com/black
> _______________________________________________
> Rails mailing list
> Rails@lists.rubyonrails.org
> http://lists.rubyonrails.org/mailman/listinfo/rails
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Michael Daines

2006-Jun-02 03:57 UTC

head link

[Rails] Set instance variable for all actions in the Controller

>   class ApplicationController < ActionController::Base
>     before_filter :set_user
>     def set_user
>       @current_user = User.find(session[:user_id])
>     end
>   end
You could also do this:

   class ApplicationController < ActionController::Base

   protected

     def current_user
       @current_user ||= User.find(session[:user_id])
     end
     helper_method :current_user

   end

Which means that you don''t look for the current user until you  
actually need to, that the implementation of getting the current user  
is hidden a little better, and lets you type one less character to  
type when getting the current user.


--
Michael Daines
http://www.mdaines.com

Jeff Ward

2006-Jun-02 07:12 UTC

head link

[Rails] Set instance variable for all actions in the Controller

Great, this works too and I''ll use it. I like that it doesn''t
get set until
I call for the variable. The only thing is I can''t restrict it to
certain
actions but for my purposes this doesn''t matter because I''m
only calling it
from actions where I need it so that''s good enough.

Thanks,

Jeff


On 6/1/06, Michael Daines <michael.daines@gmail.com>
wrote:>
> >   class ApplicationController < ActionController::Base
> >     before_filter :set_user
> >     def set_user
> >       @current_user = User.find(session[:user_id])
> >     end
> >   end
>
> You could also do this:
>
>    class ApplicationController < ActionController::Base
>
>    protected
>
>      def current_user
>        @current_user ||= User.find(session[:user_id])
>      end
>      helper_method :current_user
>
>    end
>
> Which means that you don''t look for the current user until you
> actually need to, that the implementation of getting the current user
> is hidden a little better, and lets you type one less character to
> type when getting the current user.
>
>
> --
> Michael Daines
> http://www.mdaines.com
>
> _______________________________________________
> Rails mailing list
> Rails@lists.rubyonrails.org
> http://lists.rubyonrails.org/mailman/listinfo/rails
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Vincent AE Scott

2006-Jul-28 11:08 UTC

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[Rails] Set instance variable for all actions in the Controller

#if animikii /* Jun 02, 12:11 */> 
>    Great, this works too and I''ll use it. I like that it
doesn''t get set
>    until I call for the variable. The only thing is I can''t
restrict it
>    to certain actions but for my purposes this doesn''t matter
because I''m
>    only calling it from actions where I need it so that''s good
enough.
>    Thanks,
>    Jeff
if you want to restrict access to certain actions then i suggest you
take a look at ActiveRBAC [0] which will allow you to quite easily
specify such restrictions, like this:

class MyController < ApplicationController
 before_filter :protect_controller, :except => [ :list, :index, :show ]

 def protect_controller_to_role( role )
  if !session[:rbac_user_id].nil? and
User.find(session[:rbac_user_id]).has_role?( "Admin", role )
   return true
  else
   redirect_to ''/q/list''
    flash[:notice] = "You are not allowed to access this page"
    return false
  end
 end

 def protect_controller
  protect_controller_to_role("BasicUser")
 end
end


the above restricts access to all actions in the controller except for
list, index and show, unless they have been granted the Admin or
BasicUser role.

have a look at the manual [1] for more information on what can be done.

-v

[0] https://activerbac.turingstudio.com/trac
[1] https://activerbac.turingstudio.com/releases/ActiveRbacManual.pdf


> 
>    On 6/1/06, Michael Daines <[1]michael.daines@gmail.com> wrote:
> 
>      >   class ApplicationController < ActionController::Base
>      >     before_filter :set_user
>      >     def set_user
>      >       @current_user = User.find(session[:user_id])
>      >     end
>      >   end
>      You could also do this:
>         class ApplicationController < ActionController::Base
>         protected
>           def current_user
>             @current_user ||= User.find(session[:user_id])
>           end
>           helper_method :current_user
>         end
>      Which means that you don''t look for the current user until
you
>      actually need to, that the implementation of getting the current
>      user
>      is hidden a little better, and lets you type one less character to
>      type when getting the current user.
>      --
>      Michael Daines
>      [2]http://www.mdaines.com
>      _______________________________________________
>      Rails mailing list
>      [3]Rails@lists.rubyonrails.org
>      [4]http://lists.rubyonrails.org/mailman/listinfo/rails
> 
> References
> 
>    1. mailto:michael.daines@gmail.com
>    2. http://www.mdaines.com/
>    3. mailto:Rails@lists.rubyonrails.org
>    4. http://lists.rubyonrails.org/mailman/listinfo/rails
> _______________________________________________
> Rails mailing list
> Rails@lists.rubyonrails.org
> http://lists.rubyonrails.org/mailman/listinfo/rails
#endif /* animikii@gmail.com */

-- 
keys:  http://codex.net/gpg.asc 

 I did''nt notice when the world went to shit.  I was watching TV.

Robert Mela

2006-Aug-16 03:04 UTC

head link

[Rails] Set instance variable for all actions in the Controller

before_filter :set_myvar

protected
   def set_myvar
      @myvar=''abcdefg''
   end



This probably isn''t kosher -- controller variables should be set from 
inside controllers, not layouts... but it''s neat enough that I wish 
there were a good reason to use it... you could include this in your layout:

<% @controller.instance_eval { @myvar=''foo'' } %>


Jeff Ward wrote:> Can I set an application wide instance variable that is available for 
> all actions...and their views?
>
> eg.
> class ApplicationController < ActionController::Base
>   @current_user = User.find(session[:user_id])
> end
>
> and everywhere I can call @current_user.id and I can get that object? 
> Even down in the views?
>
> I could not get this to work...
>
> Thanks in advance,
>
> Jeff
>
>
>
>
> ------------------------------------------------------------------------
>
> _______________________________________________
> Rails mailing list
> Rails@lists.rubyonrails.org
> http://lists.rubyonrails.org/mailman/listinfo/rails
>   
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