# How extend ActionController?

**URL:** <https://www.ruby-forum.com/t/how-extend-actioncontroller/137406>\
**Category:** Rails\
**Created:** [May 12, 2008, 10:11pm UTC](https://www.ruby-forum.com/t/how-extend-actioncontroller/137406 "2008-05-12T22:11:46Z")\
**Posts on this page:** 7\
**Page:** 1

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**Author:** ![S-gw](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/ed655f/32.png) [@S-gw](https://www.ruby-forum.com/u/S-gw)\
**Post date:** [May 12, 2008, 10:11pm UTC](https://www.ruby-forum.com/t/how-extend-actioncontroller/137406/1 "2008-05-12T22:11:46Z")

</div>

I have some code in ApplicationController to initialize a logging system  
I use to help write new complex stuff and trace exactly what’s going on  
during development. It’s just a few little extra steps added to the  
basic Ruby logger.

I would like to move the code into something that can be enabled with a  
command similar to how sessions or filters are used. I can’t quite  
figure out how to do this. I understand the basics of modules, but only  
half grasping how Rails is implementing this in its hierarchy.

By poking around and imitating what I am seeing, I have this so far:

module ActionController  
module RequestTrace  
def self.included(base)  
base.extend(ClassMethods)  
end

```
module ClassMethods
  def request_trace(status)
    ..... my code .....
  end
end

```

end  
end

I then add a require statement to environment.rb to load the file, but I  
keep getting the error that there’s no such method request\_trace for  
ApplicationController.

A few months ago I was ableto extend AR Validators with some custom  
ones, but the techniques I followed to do that aren’t working for this  
case either (very similar to above w/o the self.included bit).

Currently I am using 1.2.6. Any guidance much appreciated…

– gw

---

<div class="post-metadata">

**Author:** ![S-gw](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/ed655f/32.png) [@S-gw](https://www.ruby-forum.com/u/S-gw)\
**Post date:** [May 12, 2008, 10:37pm UTC](https://www.ruby-forum.com/t/how-extend-actioncontroller/137406/2 "2008-05-12T22:37:04Z")

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On 12 May 2008, at 21:11, Greg W. wrote:

> command similar to how sessions or filters are used. I can’t quite  
> figure out how to do this. I understand the basics of modules, but  
> only  
> half grasping how Rails is implementing this in its hierarchy.

I think it would help to see more of what you’ve done. What you wrote  
below seems reasonable enough, but you haven’t shown how you’re using  
or exactly what errors you’re getting.

Fred

---

<div class="post-metadata">

**Author:** ![S-gw](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/ed655f/32.png) [@S-gw](https://www.ruby-forum.com/u/S-gw)\
**Post date:** [May 13, 2008, 2:41am UTC](https://www.ruby-forum.com/t/how-extend-actioncontroller/137406/3 "2008-05-13T02:41:11Z")

</div>

On May 12, 2008, at 1:36 PM, Frederick C. wrote:

> I think it would help to see more of what you’ve done. What you wrote  
> below seems reasonable enough, but you haven’t shown how you’re using  
> or exactly what errors you’re getting.

Thanks for your time on this Fred…

This is a system adapted from a framework of my own in another  
language. There may be a more idiomatic way to do the same, but it’s  
something I implemented right away when I started with rails as  
something already familiar to me in concept and usage to help get me  
going.

Current code (distilled to essentials):

#----- environment.rb --------

require ‘init\_constants’

#----- init\_constants.rb --------

DISABLED = false  
ENABLED = 1  
CHATTY = 3  
VERBOSE = 5

TRACE\_FILE = ‘log/request\_trace.log’  
$request\_trace = DISABLED

#----- application.rb --------

class ApplicationController \< ActionController::Base

before\_filter :initialize\_response

def initialize\_response  
…other code…  
$request\_trace = ENABLED  
if $request\_trace  
File.delete(TRACE\_FILE) if FileTest::exist?(TRACE\_FILE)  
$request\_trace = Logger.new(TRACE\_FILE)  
$request\_trace.info(“ApplicationController.initialize\_response”)  
end  
…other code…  
end

#------------------------------

At this point, I can now do the following types of things in any code  
at any time…

$request\_trace.info("\__SOME\_MESSAGE\_HERE_") if $request\_trace

or to control level of detail

$request\_trace.info(“ **SOME\_MESSAGE\_HERE** ”) if $request\_trace \>=  
CHATTY

where **SOME\_MESSAGE\_HERE** is replace by some string I want written  
to the trace log.

I end up with a file which has a series of messages representing a  
“trace” through my code. I use this to track which methods are being  
called, states of vars after complex decisions and algorithms etc  
just to keep an eye on things as I code/experiment.

Maybe there’s another way to do this (i.e. more convential  
debuggers), but at this point I thought it would be an interesting  
exercise to incorporate this code so it could be used like this:

#----- application.rb --------

class ApplicationController \< ActionController::Base

before\_filter :initialize\_response  
request\_trace :chatty

And then supported by a more portable file with the guts of the  
process…

#----- request\_trace.rb --------

# would still need init\_constants

# not sure where to relocate that just yet

module ActionController #:nodoc:  
module RequestTrace #:nodoc:  
def self.included(base)  
base.extend(ClassMethods)  
end

```
 module ClassMethods
   def request_trace(status)
     case status
       when :enabled
         $request_trace = ENABLED
       when :chatty
         $request_trace = CHATTY
       when :verbose
         $request_trace = VERBOSE
       else
         $request_trace = DISABLED
     end

     if $request_trace
       File.delete(TRACE_FILE) if FileTest::exist?(TRACE_FILE)
       $request_trace = Logger.new(TRACE_FILE)
       $request_trace.info

```

(“ApplicationController.initialize\_response”)  
end  
end  
end  
end  
end

When I implement the above code, I get the following error:

NoMethodError  
undefined method `request\_trace’ for ApplicationController:Class

– gw

---

<div class="post-metadata">

**Author:** ![S-gw](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/ed655f/32.png) [@S-gw](https://www.ruby-forum.com/u/S-gw)\
**Post date:** [May 13, 2008, 2:50am UTC](https://www.ruby-forum.com/t/how-extend-actioncontroller/137406/4 "2008-05-13T02:50:31Z")

</div>

On 13 May 2008, at 01:40, Greg W. wrote:

> before\_filter :initialize\_response  
> request\_trace :chatty

You don’t seem to be actually including your RequestTrace module into  
your controller at all, you’ve just got this module hanging around on  
its own.  
For starters you could include your module into ApplicationController.  
It’s still not doing what your first example is doing (since  
request\_trace will only run once, when the class is loaded (in  
development mode that will be on each request, but that’s a red  
herring - it won’t happen in production). You probably want your  
request\_trace function to create the appropriate before\_filter or  
something like that. You could also use class\_inheritable\_accessor  
instead of a global if you want different controllers to have  
different settings.

Fred

---

<div class="post-metadata">

**Author:** ![S-gw](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/ed655f/32.png) [@S-gw](https://www.ruby-forum.com/u/S-gw)\
**Post date:** [May 13, 2008, 3:21am UTC](https://www.ruby-forum.com/t/how-extend-actioncontroller/137406/5 "2008-05-13T03:21:36Z")

</div>

On May 12, 2008, at 5:50 PM, Frederick C. wrote:

> > #----- application.rb --------
> > 
> > class ApplicationController \< ActionController::Base
> > 
> > before\_filter :initialize\_response  
> > request\_trace :chatty
> 
> You don’t seem to be actually including your RequestTrace module into  
> your controller at all, you’ve just got this module hanging around on  
> its own.

I thought that’s what that self.included/base.extend business was  
trying to do. I guess I just need to spend more time studying why the  
extensions to ActionController are different from the ones in  
ActiveRecord. Still voodoo to me.

Probably too detailed to spend time dissecting this now, but…

I’m now confused by the lack of paralellism to what I did to write  
custom validations. For that, I created a file called validators.rb,  
I “require” it in environment.rb, and it just works. No need for an  
include statement in my models, and it is structured like this:

module ActiveRecord  
module Validations  
module ClassMethods

… lots of code …  
#------------------------------------------------------------  
def validates\_as\_alpha\_numeric\_underscore(\*attr\_names)  
configuration = {  
:message =\> @@is\_alpha\_numeric\_underscore\_msg,  
:with =\> @@is\_alpha\_numeric\_underscore }  
do\_as\_format\_of(attr\_names, configuration)  
end  
… lots of code …

```
 end

```

end  
end

Description of the validations and full source code is here:  
[http://www.railsdev.ws/blog/11/custom-validations-in-rails/](http://www.railsdev.ws/blog/11/custom-validations-in-rails/)

I was hoping it was an easy detail I was missing, but sounds like I  
need a slightly different approach, so I’ll keep digging.

Thx.

– greg

---

<div class="post-metadata">

**Author:** ![S-gw](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/ed655f/32.png) [@S-gw](https://www.ruby-forum.com/u/S-gw)\
**Post date:** [May 13, 2008, 10:19am UTC](https://www.ruby-forum.com/t/how-extend-actioncontroller/137406/6 "2008-05-13T10:19:24Z")

</div>

On 13 May 2008, at 02:20, Greg W. wrote:

> > > > using  
> > > > your controller at all, you’ve just got this module hanging around on  
> > > > its own.
> 
> I thought that’s what that self.included/base.extend business was  
> trying to do. I guess I just need to spend more time studying why the  
> extensions to ActionController are different from the ones in  
> ActiveRecord. Still voodoo to me.  
> They’re not different.  
> self.included is called when you do

class SomeClass  
include SomeModule  
end  
Until you do that (or SomeClass.send :include etc…) nothing will  
happen (just creating the module in the ‘right’ namespace has no  
influence either.

> Probably too detailed to spend time dissecting this now, but…
> 
> I’m now confused by the lack of paralellism to what I did to write  
> custom validations. For that, I created a file called validators.rb,  
> I “require” it in environment.rb, and it just works. No need for an  
> include statement in my models, and it is structured like this:

The difference there is that you were adding to an existing module,  
which someone else had already included in the right place. Here  
you’ve got a new module, so you need to do the including.

Fred

---

<div class="post-metadata">

**Author:** ![S-gw](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/ed655f/32.png) [@S-gw](https://www.ruby-forum.com/u/S-gw)\
**Post date:** [May 13, 2008, 10:26am UTC](https://www.ruby-forum.com/t/how-extend-actioncontroller/137406/7 "2008-05-13T10:26:01Z")

</div>

On May 13, 2008, at 1:18 AM, Frederick C. wrote:

> > I’m now confused by the lack of paralellism to what I did to write  
> > custom validations. For that, I created a file called validators.rb,  
> > I “require” it in environment.rb, and it just works. No need for an  
> > include statement in my models, and it is structured like this:
> 
> The difference there is that you were adding to an existing module,  
> which someone else had already included in the right place. Here  
> you’ve got a new module, so you need to do the including.

Ah, that makes sense. And, I’ve come across a couple simple examples  
while research session timeout plugins where I see the Include is  
written into the init file – which for me I added to environment.rb  
after my require statement, and voila, my system works.

Thanks for your tutoring… much clearer now.

– greg