How do I specify a custom exception message from my ability.rb? - ruby-on-rails

In my ability.rb, I have the following rule:
elsif user.has_role? :demo
can :read, Profile, demo_featured: true, demo_linked: true, message: "To access this profile, please subscribe here."
But that doesn't produce the message I want.
How do I get this specific rule to produce the message I want?
Edit 1
Here is the full ability.rb if condition:
def initialize(user)
user ||= User.new # guest user (not logged in)
alias_action :create, :show, :new, :destroy, to: :csnd
if user.has_role? :admin
can :manage, :all
elsif user.has_role? :coach
# do some stuff
elsif user.has_role? :demo
can :read, Profile, demo_featured: true, demo_linked: true
elsif user.has_role? :player
# can do some stuff
else
can :read, Profile
end
end
These are some bits from my ProfilesController:
before_action :set_profile, only: [:show, :edit, :update, :destroy, :invite_user, :profiles]
def set_profile
#profile = Profile.published.includes(:grades, :positions, :achievements, :videos, :transcripts).friendly.find(params[:id])
end

This is what you are looking for:
https://github.com/CanCanCommunity/cancancan/wiki/Exception-Handling

The cancan docs give examples of customizing the message when you authorize! in the controller, and when you manually raise an error, but there doesn't seem to be any mechanism for specifying messages in ability.rb.
Instead, you could catch and modify it in your ApplicationController:
class ApplicationController < ActionController::Base
rescue_from CanCan::AccessDenied do |exception|
if current_user.has_role? :demo
redirect_to :back, :alert => "To access this profile, please subscribe here."
end
# render 403, etc.
end
end

Look for rescue_from CanCan::AccessDenied in your main application controller or in your specific controller. It should do something like redirecting to a login page. In my case it's something like this:
rescue_from CanCan::AccessDenied do ||
redirect_to new_user_session_path
end
Since you're producing a different exception message and then displaying it it'd probably be like this, using the flash:
rescue_from CanCan::AccessDenied do |exception|
flash[:notice] = exception.message
redirect_to new_user_session_path
end
Your own logic may vary depending on how you want to handle when the user doesn't have access. It's possible you may even have it setup in a per-controller basis, but this should be the gist of it.

Related

Rails CANCAN - No Access on first click

I have some trouble with Rails 4 and CanCan.
I did all like described here https://github.com/ryanb/cancan and actually it works but I have following problem:
Sometimes when I click on a link in the navi e.g. "Employee" to open the Employee/Show page CanCan fires an alert:
"...employee/?alert=You+are+not+authorized+to+access+this+page"
and I will redirected to the main page.
When I click again on the same link then page will open. No access problems now...
I dont know what the reason for this problem is... :(
I hope somebody can help.
Some Code:
ability.rb
def initialize(user)
if user.admin?
can :manage, :all
elsif user.secretary?
can :manage, :all
cannot [:destroy],[Employee, Setting, Section, Role, Position]
elsif user.leader?
can :manage, :all
cannot [:manage],[Setting, Section, Role, Position]
cannot [:destroy],[Project, Customer, Distributor]
cannot [:destroy, :edit],[Employee]
elsif user.employee?
can :manage, :all
cannot [:manage],[Setting, Section, Role, Position, Employee, Customer, Distributor]
cannot [:destroy, :edit],[Project]
else
#can :read, :all
end
end
employees_controller.rb
class EmployeesController < ApplicationController
before_action :set_employee, only: [:show, :edit, :update, :destroy]
#before_action :set_tmpPswVar, only: [:show]
#CanCan
load_and_authorize_resource
...
application_controller.rb
class ApplicationController < ActionController::Base
# Prevent CSRF attacks by raising an exception.
# For APIs, you may want to use :null_session instead.
include SessionsHelper
before_action :require_login
protect_from_forgery with: :exception
#load_and_authorize_resource
#CanCan
skip_authorization_check
#for CanCan version necessary because is not optimized for rails 4
#without that eacht create method will generate an ForbiddenAttributeError!
before_filter do
resource = controller_name.singularize.to_sym
method = "#{resource}_params"
params[resource] &&= send(method) if respond_to?(method, true)
end
#CANCAN
rescue_from CanCan::AccessDenied do |exception|
redirect_to :controller=>"workdays", :action => "index", :alert => exception.message
end
...
Best regards
Kumaro
Unfortunately CanCan does not support Rails 4+. You should instead use CanCanCan:
https://github.com/CanCanCommunity/cancancan

CanCanCan is not blocking access for users index page

I want to stop users who aren't logged in from accessing the URL using CanCanCan
http://localhost:3000/users
My Ability model is
class Ability
include CanCan::Ability
def initialize(user)
user ||= User.new # guest user (not logged in)
if user.admin?
can :manage, :all
elsif user.roles.size > 0
can :manage, User, :id => user.id
else
can :read, :all
cannot :read, :User
end
end
end
And my Users controller is
class UsersController < ApplicationController
load_and_authorize_resource
def index
#users = User.paginate(page: params[:page],:per_page => 5)
end
def new
# #user = User.new
end
...
end
When I access the page as an guest user. I see the users index page instead of being redirected to login by this code in my application controller
rescue_from CanCan::AccessDenied do |exception|
if user_signed_in?
flash[:error] = "Access denied!"
redirect_to root_url
else
flash[:error] = "Please Sign in"
redirect_to new_user_session_path
end
end
CanCanCan works and stops access to the other actions in the controller just not for index.
In my users controller I was missing
before_filter :authenticate_user!, :except => [:new, :create]
This was allowing the guest user to access the page.

User not being denied access in Active Admin using CanCan

I'm using Active Admin's CanCan authorization adapter, along with Rolify, to manage authorization on an admin site. I have a model, company, that has_many :manuals, and another model, manuals, that has_many :parts.
If a user does not have access to read admin/manuals/1 and types it into the address bar, they are redirected properly and presented with the unauthorized message. However, if the user types in admin/manuals/1/parts they are not denied access. They are taken to that page, except all the parts are hidden from them. They should be getting redirected to the dashboard with an unauthorized message.
Here is my configuration. Thanks in advance for any advice you can offer.
config/routes.rb
ActiveAdmin.routes(self)
models/ability.rb
class Ability
include CanCan::Ability
def initialize(user)
user ||= User.new
can :read, ActiveAdmin::Page, :name => "Dashboard"
if user.has_role? :admin
can :manage, :all
elsif user.has_role? :moderator
can :manage, Part, :manual => { :company_id => user.company_id }
else
can :read, Part, :manual => { :company_id => user.company_id }
end
end
end
I've also overwritten the default authorization methods in controllers/application_controller.rb
rescue_from CanCan::AccessDenied do |exception|
redirect_to root_url, :alert => exception.message
end
def authenticate_admin_user!
authenticate_user!
unless user_signed_in?
flash[:alert] = "You are not authorized to view this page"
redirect_to root_path
end
end
def current_admin_user #use predefined method name
return nil unless user_signed_in?
current_user
end
def after_sign_in_path_for(user)
if current_user.has_role? :admin
admin_dashboard_path
elsif current_user.has_role? :moderator
admin_manuals_path
else
company_path(user.company)
end
end
Did you add the method load_and_authorize_resource to your controller?
Like this:
class SomeController < ApplicationController
load_and_authorize_resource
...
end
Check Abilities & Authorization

Understanding Cancan abilities

Trying to get Cancan securing a few models in an application and curious why it's not working the way I thought it would. I had thought you could can? on the specific instance as opposed to the entire class so, not in this example but, you could enable abilities on a per instance basis as a list of posts are displayed?!?
class Ability
include CanCan::Ability
def initialize(user)
user ||= User.new # guest user (not logged in)
if user.role? :admin
can :manage, :all
elsif user.role? :moderator
can :manage, Post
else
can :read, :all
end
end
end
# posts/index.html.haml
...
- if can? :update, #post <- doesn't work
- if can? :update, Post <- works
Edit: add PostsController.rb
#posts_controller.rb
class PostsController < ApplicationController
before_filter :login_required, :except => [:index, :show]
load_and_authorize_resource :except => [:create]
def index
# #posts = Post.all ## <- handled by Cancan's load_and_authorize_resource
#events = Event.where("end_date <= :today", :today => Date.today)
#next_event = Event.next
respond_to do |format|
format.html # index.html.erb
format.json { render json: #posts }
end
end
...
end
This line:
- if can? :update, #post <- doesn't work
Is asking CanCan "can I update this specific post." You defined the ability in terms of all posts. If you had done:
can :update, Post, :user_id => user.id
Then your "if can?" would work, and the user would only be able to update their own posts. So you want to use the specific resource version ("#post") if something about this instance of the resource determines the permission, and you want to use the class version ("Post") if the user has the ability for all instances of the class.

How to obtain action level protection using Authlogic and STI?

Given that it is well-documented how to use before_filter for a single user classification, I'm having trouble getting action-level protection for multiple user types. Let me explain:
I've got something like this...
class ApplicationController < ActionController::Base
class << self
attr_accessor :standard_actions
end
#standard_actions = [:index, :show, :new, :edit, :create, :update, :destroy]
def require_guardian
unless current_user and current_user.is_a?(Guardian)
store_location
redirect_to home_url
return false
end
end
def require_admin
unless current_user and current_user.is_a?(Administrator)
store_location
redirect_to register_url
return false
end
end
end
And in the GuardiansController I want to only allow the standard actions for Administrator but all other actions should require Guardian. So I tried this...
class GuardiansController < ApplicationController
before_filter :require_admin, :only => ApplicationController::standard_actions
before_filter :require_guardian, :except => ApplicationController::standard_actions
...
end
Which ends up doing a recursive redirection. There must be a better way?
OK, this is another case of not looking carefully and missing something. I inadvertently had setup the route to redirect the user in a recursive way. The above solution works just fine when you set the routes properly:
def require_guardian
unless current_user and current_user.is_a?(Guardian)
store_location
# this route (home_url) sent the user to another controller which ran a before_filter sending them back here again.
# redirect_to home_url
# So I changed it to a neutral route and it works great!
redirect_to register_url
return false
end
end

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