Rails - Nov 2005 - How to create an object in environment.rb and use it to share data between controllers

Hi,

I was using a global ($) variable for this, but it seems global 
variables remain loaded all the time that webrick is running, and I need 
a fresh object for each HTTP request.

So I was trying to use the request.env array to add my own data there, 
but it seems that that object isn''t created in environment.rb, so I 
cannot use that approach. I need to create an object with some default 
values on environment.rb, and then each controller can override any of 
its attributes.

Could you please help me out?

- Ivan V.

ivanvega wrote:
> Hi,
> 
> I was using a global ($) variable for this, but it seems global
> variables remain loaded all the time that webrick is running, and I need
> a fresh object for each HTTP request.
> 
> So I was trying to use the request.env array to add my own data there,
> but it seems that that object isn''t created in environment.rb, so
I
> cannot use that approach. I need to create an object with some default
> values on environment.rb, and then each controller can override any of
> its attributes.
> 
> Could you please help me out?
> 
> - Ivan V.
Hey Ivan,

As newby-on-rails, I don''t know if this suggestion will be of any help 
to you, but for what it''s worth...

Because I will soon need to figure out how to do what is commonly 
referred to as an "application variable" in other languages... (i.e. a
variable that all open sessions have access to).

I started doing some research & ran across something called
"PStore".

It''s described as a way of storing session information in a file in the
tmp dir... I know this is not what you are trying to do, but since it''s
possible, I assume, to read & write to this file from anywhere in the 
app (I think read & write locking is built-in), perhaps you could use it 
for your purposes?

I haven''t figured out how to use it yet, but here''s a wiki
entry that
mentions it as well as other approaches;

http://wiki.rubyonrails.com/rails/pages/HowtoChangeSessionStore/

I hope you get a more useful answer from someone who knows far more than 
I...

Randy

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

Hey,

Thanks for the input. Unfortunately, as you point out, that''s not what 
I''m trying to do, because I need a clean object variable each time a 
page is requested, so a session/file wouldn''t work (well it could, but 
it would be very complicated and way overkill). But I''m thinking that 
might be of use for another area of my project!

I believe this is only an issue with webrick, because the application is 
running the whole time, so I suppose Apache wouldn''t have this problem 
because it runs the script from scratch for each request, I think...

Let''s hope someone can help me out!

Ivan V.

randy marmer wrote:
> ivanvega wrote:
>   
>> Hi,
>>
>> I was using a global ($) variable for this, but it seems global
>> variables remain loaded all the time that webrick is running, and I
need
>> a fresh object for each HTTP request.
>>
>> So I was trying to use the request.env array to add my own data there,
>> but it seems that that object isn''t created in environment.rb,
so I
>> cannot use that approach. I need to create an object with some default
>> values on environment.rb, and then each controller can override any of
>> its attributes.
>>
>> Could you please help me out?
>>
>> - Ivan V.
>>     
>
> Hey Ivan,
>
> As newby-on-rails, I don''t know if this suggestion will be of any
help
> to you, but for what it''s worth...
>
> Because I will soon need to figure out how to do what is commonly 
> referred to as an "application variable" in other languages...
(i.e. a
> variable that all open sessions have access to).
>
> I started doing some research & ran across something called
"PStore".
>
> It''s described as a way of storing session information in a file
in the
> tmp dir... I know this is not what you are trying to do, but since
it''s
> possible, I assume, to read & write to this file from anywhere in the 
> app (I think read & write locking is built-in), perhaps you could use
it
> for your purposes?
>
> I haven''t figured out how to use it yet, but here''s a
wiki entry that
> mentions it as well as other approaches;
>
> http://wiki.rubyonrails.com/rails/pages/HowtoChangeSessionStore/
>
> I hope you get a more useful answer from someone who knows far more than 
> I...
>
> Randy
>
>

Ivan-

	You can place a before filter in your application.rb that gets  
initialized to whatever you want on each request. Like htis:

class ApplicationController < ActionController::Base

    before_filter :setup_foo

    attr_reader :foo
    attr_writer :foo
    def setup_foo
       @foo = {:a => ''foo, :b => ''bar'', :c
=> ''qux''}
    end

end


	Now @foo will be available to all your controllers and views. And  
the attr_reader and attr_writer will set it up so your controllers  
can modify foo per request. But @foo will be reset on each request. I  
think this is what you are trying to do. Let me know if you need more  
help.

Cheers-

-Ezra


On Nov 18, 2005, at 4:57 PM, Iván Vega Rivera wrote:
> Hey,
>
> Thanks for the input. Unfortunately, as you point out, that''s not
> what I''m trying to do, because I need a clean object variable each
> time a page is requested, so a session/file wouldn''t work (well it
> could, but it would be very complicated and way overkill). But I''m
> thinking that might be of use for another area of my project!
>
> I believe this is only an issue with webrick, because the  
> application is running the whole time, so I suppose Apache
wouldn''t
> have this problem because it runs the script from scratch for each  
> request, I think...
>
> Let''s hope someone can help me out!
>
> Ivan V.
>
> randy marmer wrote:
>> ivanvega wrote:
>>
>>> Hi,
>>>
>>> I was using a global ($) variable for this, but it seems global
>>> variables remain loaded all the time that webrick is running, and  
>>> I need
>>> a fresh object for each HTTP request.
>>>
>>> So I was trying to use the request.env array to add my own data  
>>> there,
>>> but it seems that that object isn''t created in
environment.rb, so I
>>> cannot use that approach. I need to create an object with some  
>>> default
>>> values on environment.rb, and then each controller can override  
>>> any of
>>> its attributes.
>>>
>>> Could you please help me out?
>>>
>>> - Ivan V.
>>>
>>
>> Hey Ivan,
>>
>> As newby-on-rails, I don''t know if this suggestion will be of
any
>> help to you, but for what it''s worth...
>>
>> Because I will soon need to figure out how to do what is commonly  
>> referred to as an "application variable" in other
languages...
>> (i.e. a variable that all open sessions have access to).
>>
>> I started doing some research & ran across something called
"PStore".
>>
>> It''s described as a way of storing session information in a
file
>> in the tmp dir... I know this is not what you are trying to do,  
>> but since it''s possible, I assume, to read & write to this
file
>> from anywhere in the app (I think read & write locking is built- 
>> in), perhaps you could use it for your purposes?
>>
>> I haven''t figured out how to use it yet, but here''s a
wiki entry
>> that mentions it as well as other approaches;
>>
>> http://wiki.rubyonrails.com/rails/pages/HowtoChangeSessionStore/
>>
>> I hope you get a more useful answer from someone who knows far  
>> more than I...
>>
>> Randy
>>
>>
>
>
> _______________________________________________
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>
-Ezra Zygmuntowicz
Yakima Herald-Republic
WebMaster
http://yakimaherald.com
509-577-7732
ezra-gdxLOakOTQ9oetBuM9ipNAC/G2K4zDHf@public.gmane.org

Ezra Zygmuntowicz wrote:
> Ivan-
>
>     You can place a before filter in your application.rb that gets 
> initialized to whatever you want on each request. Like htis:
>
> class ApplicationController < ActionController::Base
>
>    before_filter :setup_foo
>
>    attr_reader :foo
>    attr_writer :foo
>    def setup_foo
>       @foo = {:a => ''foo, :b => ''bar'', :c
=> ''qux''}
>    end
>
> end
>
>
>     Now @foo will be available to all your controllers and views. And 
> the attr_reader and attr_writer will set it up so your controllers can 
> modify foo per request. But @foo will be reset on each request. I 
> think this is what you are trying to do. Let me know if you need more 
> help.
>
> Cheers-
>
> -Ezra
>
Thanks a lot Ezra, that''s just what I was looking for.

Ivan V.