Is this safe?

Rails
1

I am using an eval so I dont have to check avery case of a permission.

def folder_permission(folder_id, per)
permissions =
self.user_folder_permissions.find_by_folder_id(folder_id)
return true unless permissions.blank? or not
eval(“permissions.”+per)
return false
end

This function is called from private method in file controller.

def authorize_creating
unless
session[:user].folder_permision(params[:folder_id],“can_create”)
flash.now[:folder_error] = “You don’t have create permissions for
this
folder.”
redirect_to :controller => ‘file’, :action => ‘error’ and return
false
end
end

So am I safe to use this, is this efficient for ruby?

thanks

PAco

2

On Mar 26, 9:11 pm, “Paco Viramontes” [email protected] wrote:

I am using an eval so I dont have to check avery case of a permission.

def folder_permission(folder_id, per)
permissions = self.user_folder_permissions.find_by_folder_id(folder_id)
return true unless permissions.blank? or not eval(“permissions.”+per)
return false
end

I’d just write permissions.send(per) rather than use the eval. I don’t
think you’re opening yourself up to anything super bad, but it seems
like a big sledgehammer being used for a rather small nut.

Fred

3

On Mar 26, 2008, at 5:16 PM, Frederick C. wrote:

end

I’d just write permissions.send(per) rather than use the eval. I don’t
think you’re opening yourself up to anything super bad, but it seems
like a big sledgehammer being used for a rather small nut.

Fred

Go with .send(per), but doesn’t the structure of that hurt your head?!

def folder_permission(folder_id, per)
if permission =
self.user_folder_permissions.find_by_folder_id(folder_id)
permission.send(per) rescue false
else
false
end
end

Having that “unless A or not B” in there has got to be confusing (or
it will be a month from now).

-Rob

Rob B. http://agileconsultingllc.com
[email protected]

4

On Wed, Mar 26, 2008 at 5:58 PM, Rob B.
[email protected] wrote:

eval(“permissions.”+per)
Go with .send(per), but doesn’t the structure of that hurt your head?!
end

Having that “unless A or not B” in there has got to be confusing (or
it will be a month from now).

I’d consider a more radical refactoring (all untested of course):

in the models (I’m assuming the folder_permission method is in the
User model based on the controller code, and there’s a Permissions
model):

class Permissions < ActiveRecord::Base

class NoPermissions < Permissions
def can_not
false
end
[:can_create, :can_read, :can_write].each {|meth|
alias_method(meth, :can_not)}
end

def Permissions.none
@no_permissions ||= NoPermissions.new
end
end

class User < ActiveRecord::Base

def permissions_for_folder(folder_id)
user_folder_permissions.find_by_folder_id(folder_id) ||
Permissions.none
end

And the controller method becomes:

def authorize_creating
unless session[:user].
permissions_for_folder(params[:folder_id]).can_create)
flash.now[:folder_error] = “You don’t have create permissions
for this folder.”
redirect_to :controller => ‘file’, :action => ‘error’ and return
false
end
end

I might also think about renaming the can_xx methods to something like
allows_xxx? or permits_xxx? which would read a bit better I think.

–
Rick DeNatale

My blog on Ruby
http://talklikeaduck.denhaven2.com/

5

On Apr 1, 1:49 pm, “Paco Viramontes” [email protected] wrote:

user_id :integer(11) default(0)

Also if the permissions_for_folder receives folder_id why do you call it
like this?
permissions_for_folder(params[:folder_id]).can_create)

Because params[:folder_id] contains the folder_id ?

Given your schema above, it does seem like you want to use Rick’s
approach of 1) get the permissions object, 2) ask it about the
particular permission

permission_for(…).can_create?

What’s the point in having those methods if you’re going to bend over
backwards to call them via eval or send? You may want to consider
caching the retrieved permission object also.

6

Ok, thanks I like your aproach Rick but I dont quite get what your are
doung
there in the permissions model. My model actually looks like this:

== Schema Information

Schema version: 21

Table name: user_folder_permissions

id :integer(11) not null, primary key

folder_id :integer(11) default(0)

user_id :integer(11) default(0)

can_create :boolean(1)

can_read :boolean(1)

can_update :boolean(1)

can_delete :boolean(1)

class UserFolderPermission < ActiveRecord::Base
belongs_to :user
belongs_to :folder
end

Also if the permissions_for_folder receives folder_id why do you call it
like this?
permissions_for_folder(params[:folder_id]).can_create)

On Fri, Mar 28, 2008 at 6:23 AM, Rick DeNatale [email protected]