Rails - Jul 2006 - Session variable data validation

I''ve been using rails for about a month and I''ve been noticing
that most
of my controller functions use values from my session variable.  I find 
that I write something like:

person = Person.find(session[:person]
if( person )
# ...
else
  flash[:notice] = "unable to retrieve person"
  redirect_to( :action => index )
end

It seems redundant to write similar code for every action.  I could use 
a hook to check the value before each action, but then I would be 
accessing my database twice for the same data.  Is it overkill to be 
making sure something wasn''t deleted out of the database on each
action?
How bad is it if my page tries to use an objec that is nil?  What is the 
standard practice?

Thanks for your help,
Chris

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

I''ve been using rails for about a month and I''ve been noticing
that most
of my controller functions use values from my session variable.  I find 
that I write something like:

person = Person.find(session[:person])
if( person )
# ...
else
  flash[:notice] = "unable to retrieve person"
  redirect_to( :action => index )
end

It seems redundant to write similar code for every action.  I could use 
a hook to check the value before each action, but then I would be 
accessing my database twice for the same data.  Is it overkill to be 
making sure something wasn''t deleted out of the database on each
action?
How bad is it if my page tries to use an objec that is nil?  What is the 
standard practice?

Thanks for your help,
Chris

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

Maybe you can write a private method in your controller that do this 
work for you.


Chris Rericha escribi?:
> I''ve been using rails for about a month and I''ve been
noticing that most
> of my controller functions use values from my session variable.  I find 
> that I write something like:
> 
> person = Person.find(session[:person]
> if( person )
> # ...
> else
>   flash[:notice] = "unable to retrieve person"
>   redirect_to( :action => index )
> end
> 
> It seems redundant to write similar code for every action.  I could use 
> a hook to check the value before each action, but then I would be 
> accessing my database twice for the same data.  Is it overkill to be 
> making sure something wasn''t deleted out of the database on each
action?
> How bad is it if my page tries to use an objec that is nil?  What is the 
> standard practice?
> 
> Thanks for your help,
> Chris
>

Here''s how I''ve done it before...



class PersonController < ApplicationController
before_filter :get_person, :only =>[:show, :edit, :update, :delete]

def list
   @people = Person.find :all
end

def show
end

def edit
end

def update
   if @person.update_attributes params[:person]
   ....

end

def delete
    ....
end


private
  def get_person
    begin
     @person = Person.find session[:id]
    rescue
        flash[:notice] = "No person could be found with that ID."
        redirect_to :action => "list"
   end
  end

end


get_person makes @person available.  You use it as a before_filter on the
methods where you need it.

Just a thought.  Remember, if you do @ person.find params[:id] and that
person isn''t there, it will throw an exception.... your if block
won''t
work.That''s why the above block catches the exception.

This particular example has not been tested for typos but it should work for
you.

-bph


On 7/10/06, Chris Rericha < tristipher@gmail.com>
wrote:
>
> I''ve been using rails for about a month and I''ve been
noticing that most
> of my controller functions use values from my session variable.  I find
> that I write something like:
>
> person = Person.find(session[:person])
> if( person )
> # ...
> else
>   flash[:notice] = "unable to retrieve person"
>   redirect_to( :action => index )
> end
>
> It seems redundant to write similar code for every action.  I could use
> a hook to check the value before each action, but then I would be
> accessing my database twice for the same data.  Is it overkill to be
> making sure something wasn''t deleted out of the database on each
action?
> How bad is it if my page tries to use an objec that is nil?  What is the
> standard practice?
>
> Thanks for your help,
> Chris
>
> --
> Posted via http://www.ruby-forum.com/.
> _______________________________________________
> Rails mailing list
> Rails@lists.rubyonrails.org
> http://lists.rubyonrails.org/mailman/listinfo/rails
>
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Brian,

Thanks for the help!  I didn''t realize that I could access any instance
variables I create within a filter.  This makes things much easier :-).

Chris

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