Forum: Ruby on Rails can I access session variable in model

Hi
   can I access session variable in model? I have in the user controller
code
session[:site_id] = @the_site.site_id

And how can i access this in one of my active record model
SDAttachment?I tried like
site_id=session[:site_id] but this gives error. Please help

Sijo

no, you can't

If you need information from the session hash in a model,
you must hand it to the models method like:

def do_something(session_id)
...
end

and call that from the controller like

@my_model.do_something(session[:site_id])

Thorsten Mueller wrote:
> no, you can't
> 

Well, you _can_, but it's not as straight forward as you'd like. You can 
use Thread.current and store things similarly as you do with session. I 
don't know the ramifications of doing this with very much data, though. 
This thread

http://www.ruby-forum.com/topic/154820#new

mentions it. A Google search will probably turn up a bit of useful 
information.

Peace,
Phillip

Not to mention it completely violates MVC. So even if you find out
how... It's not a good idea.

RSL

On Fri, Jul 25, 2008 at 9:58 AM, Phillip Koebbe

Hi
    I have a attachment model and I use upload_column to upload files.It 
is working ..Now In ServiceDeskAttachment class i have

upload_column :attachment, :store_dir => proc{|inst, attachment| 
"uploads/servicedesk/#{@company_name}/#{inst.id}"}       # This is not 
working

My controller code for attachment is

@service_desk_attachment1= 
ServiceDeskAttachment.new(params[:service_desk_attachment1])
@service_desk_attachment1.company_name=session[:company]    #this i 
tried like from  one of above reply
@service_desk_attachment1.save

The in ServiceDeskAttachment class
def set_company(company)
    @company_name=company
    puts 'in set_company'+ company_name.to_s  #Value I get here
  end

But @company_name   how can I set this to the above upload_column so 
that it looks like
upload_column :attachment, :store_dir => proc{|inst, attachment| 
"uploads/servicedesk/company1/#{inst.id}"}

Please help
Sijo

Yes you could access the session variable in model. Paste the below
code in application.rb
--------------
around_filter :you_dont_have_bloody_clue

  protected

  def you_dont_have_bloody_clue
    klasses = [ActiveRecord::Base, ActiveRecord::Base.class]
    methods = ["session", "cookies", "params", "request"]

    methods.each do |shenanigan|
      oops = instance_variable_get(:"@_#{shenanigan}")

      klasses.each do |klass|
        klass.send(:define_method, shenanigan, proc { oops })
      end
    end

    yield

    methods.each do |shenanigan|
      klasses.each do |klass|
        klass.send :remove_method, shenanigan
      end
    end

  end
--------------

Now continue using the session variable in model. It works for me.
Thanks,
Sadeesh.



On Jul 25, 11:16 am, Sijo Kg <rails-mailing-l...@andreas-s.net> wrote:
> Hi
>    can I access session variable in model?
I have in the user controller

Hi
     Lots of thanks for your help.It is working now..But what actaully 
happened? I have the curiosity to know that..Is it anything against the 
MVC architecture? And will it create any future problems during 
deployment like that?

Thanks
Sijo

Hi,
   Probably no problem comes.I am not sure. Its your responsibilty.
And you could access all these variables there
   ["session", "cookies", "params", "request"] .

   Thanks,
   Sadeesh.

Hi --

On Sat, 26 Jul 2008, Sijo Kg wrote:

>
> Hi
>     Lots of thanks for your help.It is working now..But what actaully
> happened? I have the curiosity to know that..Is it anything against the
> MVC architecture? And will it create any future problems during
> deployment like that?

If you're talking about the code with "you_dont_have_bloody_clue" and
so forth, don't use it. It was some kind of joke, I believe.

The model has no concept of a "session". It shouldn't be able to tell
whether it's being accessed from a controller or the console or a
standalone script. It's only the controller that knows about sessions.

As another respondent said, if you need the model to have session
data, you should write your model method to take an argument and then
pass the relevant session data in. The model doesn't know where the
method argument comes from, and it shouldn't know.


David

--
Rails training from David A. Black and Ruby Power and Light:
  *  Advancing With Rails    August 18-21    Edison, NJ
  * Co-taught by D.A. Black and Erik Kastner
See http://www.rubypal.com for details and updates!

Hi
     The code is not a joke .It is working anyway..And I tried as you 
said.(5 th post above)..In the model ServiceDeskAttachment i made a 
attr_accessor :company
And from controller I wrote
@sd_attachment=ServiceDeskAttachment.new(params[:attachment_data])
@sd_attachment.company=session[:company]
@sd_attachment.save

And in ServiceDeskAttacment model I I have the following code at top
upload_column :attachment, :store_dir => proc{|inst, attachment|
"uploads/servicedesk/#{@company}/#{inst.id}"}

But this does not get @company value...If I get value there,  then my 
problem is solved..Could you please tell me how can this be solved?

Thanks in advance
sijo

On Jul 27, 2008, at 9:55 PM, Sijo Kg wrote:

> And in ServiceDeskAttacment model I I have the following code at top
> upload_column :attachment, :store_dir => proc{|inst, attachment|
> "uploads/servicedesk/#{@company}/#{inst.id}"}
>
> But this does not get @company value...If I get value there,  then my
> problem is solved..Could you please tell me how can this be solved?



The whole thing is just not a good idea. If your model needs external
data, then pass it in.
When classes have direct access to things that do not belong to them
then you're building a house of cards.

If you have a model that needs some external data, then pass it in as
an argument.

Hi --

On Mon, 28 Jul 2008, Sijo Kg wrote:

>
> Hi
>     The code is not a joke .It is working anyway..And I tried as you

Sorry. I assumed it was a joke, and not a very nice one, because of
the whimsical method and variable names (like "you_dont_have_a_clue"
and so forth). If it's not a joke, then I would still say it's not a
good idea to try to make the model automatically aware of the concept
of "session".


David

--
Rails training from David A. Black and Ruby Power and Light:
  *  Advancing With Rails    August 18-21    Edison, NJ
  * Co-taught by D.A. Black and Erik Kastner
See http://www.rubypal.com for details and updates!

http://m.onkey.org/2007/10/17/how-to-access-sessio...

I don't think the message could have been any cleaerer. But if it
helps. let me say it again as the original author of that code :  DO
NOT USE IT.

On Mon, Jul 28, 2008 at 3:57 PM, David A. Black <dblack@rubypal.com> 
wrote:
> the whimsical method and variable names (like "you_dont_have_a_clue"
>  * Co-taught by D.A. Black and Erik Kastner
> See http://www.rubypal.com for details and updates!
>
> >
>



--
Cheers!
- Pratik
http://m.onkey.org

Hi --

On Tue, 29 Jul 2008, Pratik wrote:

>> Sorry. I assumed it was a joke, and not a very nice one, because of
>
> I don't think the message could have been any cleaerer. But if it
> helps. let me say it again as the original author of that code :  DO
> NOT USE IT.

I take back the "not a very nice one" thing, which had to do with my
thinking that the method and variable names were being hurled at a
particular person. I'm not sure "nice" describes the original, but
neither does "not nice." Its niceness is nil, rather than false :-)
(And the message certainly looks clear to me.)


David

--
Rails training from David A. Black and Ruby Power and Light:
  *  Advancing With Rails    August 18-21    Edison, NJ
  * Co-taught by D.A. Black and Erik Kastner
See http://www.rubypal.com for details and updates!

Hey David,

Sorry, I didn't mean to quote you ( just pressed gmail reply button ).
My message was not for you, but for the people using the code :)

On Tue, Jul 29, 2008 at 5:36 PM, David A. Black <dblack@rubypal.com> 
wrote:
>>>
>>>
> thinking that the method and variable names were being hurled at a
>  * Co-taught by D.A. Black and Erik Kastner
> See http://www.rubypal.com for details and updates!
>
> >
>



--
Cheers!
- Pratik
http://m.onkey.org

Hi,

I have a scenario where the session variable is handy in the model - I 
need to be able to get the current value, as it may be changed at any 
time.

I have a delayed_job that runs a long running model activity (calling 
multiple web services, populating the database, etc.) in the background. 
This is triggered when a user selects an item from a list in the UI. 
However, if the user clicks on another item, I want the current 
processing to stop, as I want to keep the delayed_job worker pool as 
free as possible (the more the jobs, the more I am billed by the 
hoster). The only way I can see to achieve this is to set a session 
variable (session[:current_topic_id]) when the user clicks on a topic, 
and then check in each stage of the model action if the current topic is 
the same as the one stored in the session, and abort the long job if 
they are out of sync.

Here, passing in the session variable to the model method wont really 
work for me, I have to pass in the session id and check the variable 
value across the model code.

Thanks
Anand

Pratik Naik wrote:
> Hey David,
> 
> Sorry, I didn't mean to quote you ( just pressed gmail reply button ).
> My message was not for you, but for the people using the code :)
> 
> On Tue, Jul 29, 2008 at 5:36 PM, David A. Black <dblack@rubypal.com> 
> wrote:
>>>>
>>>>
>> thinking that the method and variable names were being hurled at a
>>  * Co-taught by D.A. Black and Erik Kastner
>> See http://www.rubypal.com for details and updates!
>>
>> >
>>
> 
> 
> 
> --
> Cheers!
> - Pratik
> http://m.onkey.org

Sadeesh Viswanthan wrote:
> Yes you could access the session variable in model. Paste the below
> code in application.rb
> --------------
> around_filter :you_dont_have_bloody_clue
> 
>   protected
> 
>   def you_dont_have_bloody_clue
>     klasses = [ActiveRecord::Base, ActiveRecord::Base.class]
>     methods = ["session", "cookies", "params", "request"]
> 
>     methods.each do |shenanigan|
>       oops = instance_variable_get(:"@_#{shenanigan}")
> 
>       klasses.each do |klass|
>         klass.send(:define_method, shenanigan, proc { oops })
>       end
>     end
> 
>     yield
> 
>     methods.each do |shenanigan|
>       klasses.each do |klass|
>         klass.send :remove_method, shenanigan
>       end
>     end
> 
>   end
> --------------
> 
> Now continue using the session variable in model. It works for me.
> Thanks,
> Sadeesh.

If I had a programmer working on my team and I ran across code like 
this, well he wouldn't be working on my team long. Just saying.

I am firmly rooted in the camp where model code is decoupled from 
external data such as session, request or whatever else is the 
responsibility of the View or Controller layers.

I tried passing the session id around to the model, and agree that it is
very ugly.

I am curious to know how you can best achieve this scenario without 
passing
in the session variable: abort a delayed_job (or other model based) work
item when user changes something - this is mainly required because 
delayed
job workers cost money at my host (heroku) and if the user randomly 
clicks
around on the UI, I dont want to be billed for all the spawned jobs that 
no
one cares about anyway.

Thanks
Anand

We can do that with attr_accessor

In model
attr_accessible :site_id
attr_accessor :site_id


in form, add a hidden field like this

=f.site_id, value; session[:site_id]

in model we can use self.site_id now.