Using CanCan to assign permissions to roles - ruby-on-rails

I have a rails application where I have set up a table: users another table: roles and finally a join table: user_roles where a user may have many roles, but a role belong_to_and_has_many :users
This has allowed me to create new roles and then, assuming thee user is an admin, on the user edit page, switch their role.
This is great, how ever currently no role has capabilities. What I was thinking was doing:
role_permissions table
permissions: has_and_belongs_to_many :roles
Setting up a set of checkboxes on the roles edit page to assign a set of capabilities
to said role, that can then be applied to said user, that can then be used by capybara to determine if a user has the appropriate action or not.
While you can create roles, you cannot create capabillities. so you would have a predetermined list of capabilities. Also some roles, such as administrator or member could not be destroyed or edited. (already done.)
I can set up the table and the relationship to do this, what I cannot figure out how to do is to integrate this concept with cancan. Because can can does something like:
can? :destroy #project
If I assign, say:
Role: Editor (String name)
Capabilities: Read, Write, Destroy, Update, Preview (These are just string names)
How could I then say:
can? user.role? Editor read Post - seudo code.

First of all, for capabilities, if it's a fixed list of capabilities you're working with, you're probably better off with having a number of booleans on the roles table, e.g. can_create_projects, can_create_users, etc., which encode the abilities of each role.
Then your CanCan Ability class might have something like the following,
class Ability
include CanCan::Ability
def initialize(user)
can(:create, Project) do |project|
user.roles.any?(&:can_create_projects)
end
end
end

Related

Who handle the roles of a User in Rails?

I'm making a Rails 6 application where I'm using Devise for authentication, Pundit for authorization and I added Active-Admin because I need a dashboard where admin users manage the content of the app.
Other than admin, I have a couple of more roles president, manager, guest. An admin can be president or manager.
I'm little confuse on what to use to implement the roles, with devise? pundit? I do it by hand?
Is it better to unite the User and the AdminUser model active-admin created? Because this way UserAdmin users can't log in to the application, only to the dashboard and that is not what I want.
I have seen tutorials where people add an admin:boolean column to the users, should I do something like that?
Is it better to unite the User and the AdminUser model active-admin created? Because this way UserAdmin users can't log in to the application, only to the dashboard and that is not what I want.
That depends more on your business logic. It may be a good idea to keep your users and admin_users tables separated; The users table will probably need to have a lot of associations with other tables, that will not be necessarily needed by admin_users, right?
I'm little confuse on what to use to implement the roles, with devise? pundit? I do it by hand?
You may define a role column in your admin_users table, and use that column in pundit policies, for example:
class ResourcePolicy
# ...
# ...
# ...
def update?
user.admin? || user.president?
end
end
in AdminUser, you can do the following:
class AdminUser < ActiveRecord::Base
def admin?
role == 'admin'
end
def president?
role == 'president'
end
end
There are many other ways to implement that, and they all depend on what you need to achieve.

How should I structure two types of Roles in a Rails application?

I am working on a Ruby on Rails application that has two kinds of "Roles".
One will be where a user has multiple roles, such as "Admin", "Team Lead", etc. these will be defined in the seeds file and not generated by the user.
The other will be generated by a User and assigned to other users, such as "Chef", "Waiter", etc.
They are both similar in that they only have a name column. The former will be used with an authorization tool such as CanCanCan. I currently plan to allow users and roles to have many of the other using a has_many :through relationship.
class Role
has_many :user_roles
has_many :users, through: :user_roles
end
class User
has_many :user_roles
has_many :roles, through: :user_roles
end
class UserRole
belongs_to :user
belongs_to :role
end
My questions are:
Should the latter ("Chef", "Waiter", etc) be put in the same table? Separate tables?
Should I use some kind of inheritance?
What's a good practice for this situation?
I plan to use the term "Role" in the user interface for the latter, showing what "Roles" a user has. The former I guess is more about what privileges they have within the application.
If you go away from the technical side of roles and authentication, and try to describe the "things" from a more business oriented approach you make the distinction clearer for yourself.
What I understand is: You have a definition for a user of your application that is used to describe what authorization this user has, e.g. an "admin" has more rights than an "editor" or "community manager".
You also want these users of your application to be able to create names that are associated with (other?) users. Theses names have nothing to do with authorization, as I understood.
Maybe these names are more like tags, that people can assign?
I would keep both separated, as it shouldn't be able for a user to create a role, or modify existing roles, that could grant them access to admin features.
If you want to look at a tagging gem, I could recommend this one: https://github.com/mbleigh/acts-as-taggable-on I used this for several years and while it has its drawbacks, it's reliable.
I'd suggest having a look at rolify before rolling your own solution, as it will have solved some things that you'll have to reimplement / discover later (e.g. role queries, avoiding N+1 queries etc). It also integrates well with can?, and should work well for the authorisation part of your question.
Whilst it's not impossible to allow users to create new roles (by throwing an input form on top of Role.create), this starts to get messy, as you need to track which ones are for authorisation and which ones informative (and user created).
Since the two groups of things are for different purposes, I wholeheartedly agree with this other answer that it's cleaner to separate the user-generated entities, and look to implement them as tags. You may display all the "roles" together in certain views, but that doesn't mean that it makes sense to store them within a single table.
Side-note: if you do end up rolling your own solution, consider using HABTM here. The join table will still be created, but you won't have to manage the join table model. E.g.
has_and_belongs_to_many :users, join_table: :users_roles
Since you only have a limited number of roles, you could use a bitmask and store directly on the user model as a simple integer.
See this Railscasts for more information. That would be the most efficient, database and association wise, way to do this although perhaps not the simplest to understand. The only real restriction is that you can't alter the array of values you check against, only append to it.
Good luck!
I would create one more model, Permission, where you can create a list of all the permissions you want to manage under any given role.
Then have a many to many between Permissions and Roles.
From a UserRole instance then you will be able to list the permissions, and in the future you could add additional permissions to roles buy just running inserts in a couple of tables
Roles: Onwer, Chef, Cook, Waiter
Permission: can_cook, can_buy_wine, can_manage, can_charge_custome
Owner: can_manage, can_buy_wine, can_charge_customer
Chef: can_cook, can_manage
Waiter: can_charge_customer
Is would be a good start and you can evolve the role functionality to whatever your needs are without an external dependency.
Also, You can go just using Users table and adding role column as integer and give them a role code in default 0 integer.
#app/helpers/roles_helper.rb
module RolesHelper
#roles = {
'Default' => 0,
'Waiter' => 10,
'Chef' => 20,
'Superadmin' => 30
}
class << self
def list_roles
#roles.map{|k,v| [k,v] }
end
def code(str)
return #roles[str]
end
def value(id)
return #roles.key(id)
end
end
def require_default_users
unless current_user && current_user.role >= RolesHelper.code('Waiter')
redirect_to root_url(host: request.domain)
end
end
def require_superadmin_users
unless current_user && current_user.role >= RolesHelper.code('Superadmin')
redirect_to courses_path
end
end
end
access in controllers
sample:
class Admin::AdminController < ApplicationController
include RolesHelper
def sample_action_method
require_default_users #if non admin user redirect ...
puts "All Roles: #{RolesHelper.list_roles}"
puts "Value: #{RolesHelper.value(30)}"
puts "Code: #{RolesHelper.code('Superuser')}"
end
end

How to give permissions to create only User role to manager in Spree?

Currently i have two roles, the defaults, 'User' and 'Admin'.
And i added a new role called 'Manager' with the permissions to manage Order, User
class ManagerAbility
include CanCan::Ability
def initialize user
if user.has_spree_role?(:manager)
can :manage, Spree::Order
can :manage, Spree::User
end
end
end
If the Manager is logged in he can able to manage Orders and Users, Her he can able to create new User with Admin role. But I need an ability to create only 'User' not 'Admin' or other 'Manager' roles.
Using spree_auth_devise - 2-2-stable
I appreciate if any one can help me out. Thank you.
This is not somthing that is currently supported by Spree out of the box.
You're going to have to modify Spree's UsersController in order to add this restriction. It currently doesn't support any restrictions on roles. You will need to modify (at a minimum) the create and update functions to put a check to see if the logged in user is allowed to create/update a user to the newly selected role.

Devise/CanCan - Restricted Content

Building a rails B2B application that will have various users. I'm pretty clear on restricting access for internal staff using Devise and CanCan but I want to be able to give suppliers and customers their own login as well. Customer will be fairly simple, however, I want to ensure the supplier (label) login enables them to view and amend their own product and sales data only.
The model is roughly:
User (as setup by Devise)
Label [has_many releases]
Release [belongs_to label / has_many products]
Product [belongs_release / has_many tracks]
Track [belongs_product]
I'm guessing I could add in a label_id field on the user model and associate that way but I need internal users (and customers) to have access to view all label data. I also need to allow a label to have many users.
Would it simply be a case of defining a 'label' role via Cancan that enforces the use of a label_id in the the views? If that's the correct approach how do I then lock down the content to that label_id in my controllers/views? Role based if statements?
Thanks in advance!
What you'd first have to do is define some CanCan roles, like supplier, customer and staff, and then create an interstitial controller to handle the forking:
class CheckingController < ApplicationController
def index
#path = case user.role
when 'supplier'
supplier_path
when 'customer'
customer_path
when 'staff'
staff_path
else
admin_sign_in_path #or whatever
end
redirect_to #path
end
end
Then in your routes.rb file you can send users to either the root or index action of your controller by first sending them to CheckingController#index which will redirect based on your CanCan roles.

RoR: Different user roles for each new created record?

I want to make a record management system. The system will have 4 different user roles: Admin, Viewer, Editor and Reviewer.
While the first two are easy to implement using gems such as cancan and declarative authorization, the other two are not so simple.
Basically each new record is created by an Admin (only an Admin can create new records), and should have its own separate Editor and Reviewer roles. That is, a user can be assigned many different roles on different records but not others, so a user might be assigned Editor roles for Record A and C but not B etc.
Editor: can make changes to the record, and will have access to specific methods in the controller such as edit etc.
Reviewer: will be able to review (view the changes) made to the record and either approve it or submit comments and reject.
Viewer: Can only view the most recent approved version of each record.
Are there any ways of handling such record-specific user roles?
This can be accomplished without too much effort with the cancan gem and a block condition. A block condition checks for authorization against an instance. Assuming your Record class had an editors method that returns an array of authorized editors the cancan ability for updating a Record might look something like this:
class Ability
include CanCan::Ability
def initialize(user)
user ||= User.new # guest user (not logged in)
...
can :update, Record do |record|
record.editors.include?(user)
end
...
end
end
See "Block Conditions" on the CanCan wiki:
https://github.com/ryanb/cancan/wiki/Defining-Abilities
Update
Storing which users have which access to which records could be done many ways depending on your specific needs. One way might be to create a model like this to store role assignments:
class UserRecordRoles < ActiveRecord::Base
# Has three fields: role, user_id, record_id
attr_accessible :role, :user_id, :record_id
belongs_to :user_id
belongs_to :record_id
end
Now create a has_many association in the User and Record models so that all role assignments can be easily queried. An editors method might look like this:
class Record < ActiveRecord::Base
...
has_many :user_record_roles
def editors
# This is rather messy and requires lot's of DB calls...
user_record_roles.where(:role => 'editor').collect {|a| a.user}
# This would be a single DB call but I'm not sure this would work. Maybe someone else can chime in? Would look cleaner with a scope probably.
User.joins(:user_record_roles).where('user_record_roles.role = ?' => 'editor')
end
...
end
Of course there are many many ways to do this and it varies wildly depending on your needs. The idea is that CanCan can talk to your model when determining authorization which means any logic you can dream up can be represented. Hope this helps!

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