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ct9a

2011-Jun-01 10:36 UTC

Creating common method in application ontroller

hi, guys,
 I would like to define a common method in the application controller
because the other resources will use this method.

Scenario: I have 2 resources: Posts (for blogs) and Coupons.

Common method: is_owner_or_admin( object )

I have defined this method within the application controller as I
figured it''s akin the base class that the controllers for the
resources will inherit from.
I''m just testing the syntax call so, please don''t look at this
from a
process design point of view :)

application_controller.rb
================

class ApplicationController < ActionController::Base
    protect_from_forgery

    def is_owner_or_admin(obj)
      @part = Part.find(params[:id])
      @current_user = get_current_user

       if ( @current_user == nil )
         flash[:notice] = ''Access denied''
         redirect_to root_url
         return false
       elsif ( @current_user.is_admin or (@current_user.login =@part.created_by)
)
         return true
       else
         flash[:notice] = ''Access denied''
         redirect_to root_url
         return false
       end
    end
end


I''m trying to call this method in each of the before_filter in the
resources  (ie. Posts, Coupons).
So, in posts_controller.rb , I do:


class PostsController < ApplicationController
    before_filter :authenticate_user!,
        :except => [:index, :show, :send_message, :get_subcategories]

     ...

    def show
        @post = Post.find(params[:id])
        :is_owner_or_admin(@post)

        respond_to do |format|
            format.html # show.html.erb
            format.xml  { render :xml => @post }
        end
    end

   .....

end



Anyway, when I run the rails server or run "ruby -w
posts_controller.rb", I get the following error:

/home/ct9a/projects/port_over_to_rails3/app/controllers/
posts_controller.rb:20: syntax error, unexpected ''('',
expecting
keyword_end
		:is_owner_or_admin(@post)
		                              ^

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Michael Pavling

2011-Jun-01 10:50 UTC

head link

Re: Creating common method in application ontroller

On 1 June 2011 11:36, ct9a
<anexiole-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:> Scenario: I have 2 resources: Posts (for blogs) and Coupons.
>
> Common method: is_owner_or_admin( object )
>
> I have defined this method within the application controller as I
> figured it''s akin the base class that the controllers for the
> resources will inherit from.
You might find it makes more sense as a method on the objects
themselves - it''s a bit more in the spirit of OO this way too, whereas
the "common method" in application_controller is a bit imperative.

So you can do stuff like:
  coupon = Coupon.new
    if coupon.is_owned_or_administered_by(current_user) # no need to
put the result of "get_common_user" in an instance variable - and
"common_user" is a bit more commonly used
    # do your stuff here...
  end
> So, in posts_controller.rb , I do:
>
> class PostsController < ApplicationController
>    before_filter :authenticate_user!,
>        :except => [:index, :show, :send_message, :get_subcategories]
>
>    def show
>        @post = Post.find(params[:id])
>        :is_owner_or_admin(@post)
>
Looks like you''re reinventing authorization processes - it would save
you some time if you looked at Aegis, CanCan and the like...
> /home/ct9a/projects/port_over_to_rails3/app/controllers/
> posts_controller.rb:20: syntax error, unexpected ''('',
expecting
> keyword_end
>                :is_owner_or_admin(@post)
well yes - symbols aren''t method calls.

You should really be looking at either doing:
  @post.is_owner_or_admined_by(current_user)
or
  current_user.owns_or_administers(@post)
which way round is your choice, and either way can be utilised in the
permissions model of your chosen authentication gem.

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ct9a

2011-Jun-01 11:36 UTC

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Re: Creating common method in application ontroller

hi there, Michael,

 Good evening :)

 I''m just trying to figure out how to make functions in the base class
(application controller) such that resources/objects inheriting from
the base class will be able to use them.



1. I''ve actually got an existing application which has the method
implemented individually (ie. is_owner_or_admin() is being implemented
in posts_controller.rb and coupons_controller.rb).
2. the purpose of this method is to return true if the current object
is being accessed by its owner/creator OR by an admin user. Hence, I
wanted to extract that functionality into a base class (ie. the
application controller) and pass that method an object to evaluate.
3. I am trying to port over a rails 2.3.8 application into rails 3. In
rails 2.3.8, i was using authlogic but in my attempt to port it over
to rails 3, i am using devise. I do not think device would have any
functionality as described in the previous point (2) but i might just
look at Aegis, CanCan and some others for reference.
4. Your reply on "symbols aren''t method calls" is so right :)

 I think I might have figured out how to solve my initial problem :)

Thank you :)

Gordon Yeong


On Jun 1, 8:50 pm, Michael Pavling
<pavl...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:> On 1 June 2011 11:36, ct9a
<anexi...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
>
> > Scenario: I have 2 resources: Posts (for blogs) and Coupons.
>
> > Common method: is_owner_or_admin( object )
>
> > I have defined this method within the application controller as I
> > figured it''s akin the base class that the controllers for the
> > resources will inherit from.
>
> You might find it makes more sense as a method on the objects
> themselves - it''s a bit more in the spirit of OO this way too,
whereas
> the "common method" in application_controller is a bit
imperative.
>
> So you can do stuff like:
>   coupon = Coupon.new
>     if coupon.is_owned_or_administered_by(current_user) # no need to
> put the result of "get_common_user" in an instance variable - and
> "common_user" is a bit more commonly used
>     # do your stuff here...
>   end
>
> > So, in posts_controller.rb , I do:
>
> > class PostsController < ApplicationController
> >    before_filter :authenticate_user!,
> >        :except => [:index, :show, :send_message,
:get_subcategories]
>
> >    def show
> >        @post = Post.find(params[:id])
> >        :is_owner_or_admin(@post)
>
> Looks like you''re reinventing authorization processes - it would
save
> you some time if you looked at Aegis, CanCan and the like...
>
> > /home/ct9a/projects/port_over_to_rails3/app/controllers/
> > posts_controller.rb:20: syntax error, unexpected
''('', expecting
> > keyword_end
> >                :is_owner_or_admin(@post)
>
> well yes - symbols aren''t method calls.
>
> You should really be looking at either doing:
>   @post.is_owner_or_admined_by(current_user)
> or
>   current_user.owns_or_administers(@post)
> which way round is your choice, and either way can be utilised in the
> permissions model of your chosen authentication gem.
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Michael Pavling

2011-Jun-01 11:58 UTC

head link

Re: Re: Creating common method in application ontroller

On 1 June 2011 12:36, ct9a
<anexiole-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:> hi there, Michael,
>
>  Good evening :)
>
>  I''m just trying to figure out how to make functions in the base
class
> (application controller) such that resources/objects inheriting from
> the base class will be able to use them.
well, you''ve done that already - any method you write in
application_controller is available to any class that inherits from
it.
> 1. I''ve actually got an existing application which has the method
> implemented individually (ie. is_owner_or_admin() is being implemented
> in posts_controller.rb and coupons_controller.rb).
But what happens when you''re not using a controller; maybe when
you''re
at the console, or in a script? - then these methods wouldn''t be
available. They relate to the objects - so they should (on balance)
live there. If you think they should be in the application_controller
(or any individual controller) that''s probably the old procedural
programming habits showing their heads :-)
> 3. I am trying to port over a rails 2.3.8 application into rails 3. In
> rails 2.3.8, i was using authlogic but in my attempt to port it over
> to rails 3, i am using devise. I do not think device would have any
> functionality as described in the previous point (2) but i might just
> look at Aegis, CanCan and some others for reference.
Devise is for authentication (logging in), Aegis & CanCan are for
authorization (can a user, logged in or not, do this thing...) -
they''re very different problem domains.

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Gordon Yeong

2011-Jun-01 12:10 UTC

head link

Re: Re: Creating common method in application ontroller

>
>
>  But what happens when you''re not using a controller; maybe when
you''re
> at the console, or in a script? - then these methods wouldn''t be
> available. They relate to the objects - so they should (on balance)
> live there. If you think they should be in the application_controller
> (or any individual controller) that''s probably the old procedural
> programming habits showing their heads :-)
>
>yeah, in some ways, that has shown some procedural programming trait (my day
job sees me coding in both procedural and OO environments and my arguments
to totally be rid of procedural programming have been knocked back strongly
:( ).

Yes, that is a valid point but given that the resources I deal with can only
work in the web domain as the app i have here is very simple albeit I do
deal with applications that have deal with data on and offline (xml file
transfers and etc) :)



> Devise is for authentication (logging in), Aegis & CanCan are for
> authorization (can a user, logged in or not, do this thing...) -
> they''re very different problem domains.
>
Yep, you''re right, Michael :)
For my own app, I have just simplified it to have 2 types of users
(ie. ''admin'' and ''regular'' types).
Hence, I done away with using authorization gems as it''s a simple
application :)


Sweet. Nice discussion. Thank you :)

Loving rails since ver 2.3.x and finding sanity in it,
Gordon Yeong :)

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Michael Pavling

2011-Jun-01 12:36 UTC

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Re: Re: Creating common method in application ontroller

On 1 June 2011 13:10, Gordon Yeong
<anexiole-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:> my arguments
> to totally be rid of procedural programming have been knocked back strongly
> :( ).
You don''t fix that by still using procedural methods when
you''re
working in Rails ;-)

Demonstrate the efficiencies of following OO methods, and there''s no
argument. There''s very few occasions when a procedural approach is
better. The smaller the app, the more important following the design
standards is, so you can change it quickly later - no client likes
hearing "we''ll have to rewrite the whole thing to do that..."
when
they ask for a little extra functionality to a ''simple'' site
(I
know... I''ve had to say it in the past! :-D

Regards,

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Gordon Yeong

2011-Jun-01 12:48 UTC

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Re: Re: Creating common method in application ontroller

Yep, agreed. Using rails and domolicious just reinstates my sanity (ie OO
methodology) which I work with after my day job.

Seems what I have done in my rails 2.3.8 application was right all along as
in, i declared the method for each resource and called the method within the
resource''s object (ie. post.is_owner_or_admin and
coupon.is_owner_or_admin)
:)

Cheers :D



On 1 June 2011 22:36, Michael Pavling
<pavling-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> On 1 June 2011 13:10, Gordon Yeong
<anexiole-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> > my arguments
> > to totally be rid of procedural programming have been knocked back
> strongly
> > :( ).
>
> You don''t fix that by still using procedural methods when
you''re
> working in Rails ;-)
>
>
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Kevin

2011-Jun-03 17:34 UTC

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Re: Re: Creating common method in application ontroller

Out of curiosity what should one do if one wants to have a method inherited 
by all models?  Does rails already have a file for adding methods to the 
model base class?  Or do we just ram our methods into ActiveModel and call 
it a day?  I have run into almost the opposite scenario as the thread 
starter.  Mainly with certain integrity checks I''ve needed to perform.

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Michael Pavling

2011-Jun-03 17:41 UTC

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Re: Re: Creating common method in application ontroller

On 3 June 2011 18:34, Kevin
<darkintent-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:> Out of curiosity what should one do if one wants to have a method inherited
> by all models?
You can monkey patch Object or Class if you really want...

# patch in environment.rb
class Object
  def your_method
    puts "my method is here"
  end
end

# console>> o = AnyObject.new
=> #<AnyObject id: etc>>> o.your_methodmy method is here
=> nil>> String.your_methodmy method is here
=> nil

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Gordon Yeong

2011-Jun-03 22:38 UTC

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Re: Re: Creating common method in application ontroller

Monkey patches are evil.
On Jun 4, 2011 3:42 AM, "Michael Pavling"
<pavling-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:> On 3 June 2011 18:34, Kevin
<darkintent-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
>> Out of curiosity what should one do if one wants to have a method
inherited>> by all models?
>
> You can monkey patch Object or Class if you really want...
>
> # patch in environment.rb
> class Object
> def your_method
> puts "my method is here"
> end
> end
>
> # console
>>> o = AnyObject.new
> => #<AnyObject id: etc>
>>> o.your_method
> my method is here
> => nil
>>> String.your_method
> my method is here
> => nil
>
> --
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Colin Law

2011-Jun-04 07:54 UTC

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Re: Re: Creating common method in application ontroller

On 3 June 2011 18:34, Kevin
<darkintent-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:> Out of curiosity what should one do if one wants to have a method inherited
> by all models?  Does rails already have a file for adding methods to the
> model base class?  Or do we just ram our methods into ActiveModel and call
> it a day?  I have run into almost the opposite scenario as the thread
> starter.  Mainly with certain integrity checks I''ve needed to
perform.
Can one derive a class for ActiveModel, put the common methods in
there, and then derive the models from that?  I have not tried it.

Colin

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Michael Pavling

2011-Jun-04 11:26 UTC

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Re: Re: Creating common method in application ontroller

On 3 June 2011 23:38, Gordon Yeong
<anexiole-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:> On Jun 4, 2011 3:42 AM, "Michael Pavling"
<pavling-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
>> You can monkey patch Object or Class if you really want...
>
> Monkey patches are evil.
"Evil" is a bit strong :-)

They can have a place. I''ve found it invaluable in the past to add a
patch for ActiveRecord::Errors to merge two error objects'' messages
together.

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Kevin

2011-Jun-04 20:49 UTC

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Re: Re: Creating common method in application ontroller

Google seems to indicate that one may simply mixin (Is that the correct Ruby 
terminology.) parts of ActiveModel into any class as one sees fit. For 
example:http://yehudakatz.com/2010/01/10/activemodel-make-any-ruby-object-feel-like-activerecord/
If memory about the way inheritance works in Ruby serves me we should be 
able to do something like that, without even needing to derive from 
ActiveModel directly.  Though in the case of a Rails application one would 
probably just create a stub class that derives from ActiveRecord::Base stick 
the common methods in there and then subclass that class since ActiveModel 
does not include the database related functionality.
 

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Gordon Yeong

2011-Jun-05 00:05 UTC

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Re: Re: Creating common method in application ontroller

hi, Michael:)

 they are evil when you have to decommission some gems that are no longer
supported and change from one rails 2.3.x-1 to rails 2.3.x. I had that in
the past about a year plus... Madness lol



On 4 June 2011 21:26, Michael Pavling
<pavling-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> On 3 June 2011 23:38, Gordon Yeong
<anexiole-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> > On Jun 4, 2011 3:42 AM, "Michael Pavling"
<pavling-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> >> You can monkey patch Object or Class if you really want...
> >
> > Monkey patches are evil.
>
> "Evil" is a bit strong :-)
>
> They can have a place. I''ve found it invaluable in the past to add
a
> patch for ActiveRecord::Errors to merge two error objects''
messages
> together.
>
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Rails - Jun 2011 - Creating common method in application ontroller

Creating common method in application ontroller

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Re: Re: Creating common method in application ontroller

Re: Re: Creating common method in application ontroller

Re: Re: Creating common method in application ontroller

Re: Re: Creating common method in application ontroller

Re: Re: Creating common method in application ontroller

Re: Re: Creating common method in application ontroller

Re: Re: Creating common method in application ontroller