layout: default nav_order: 13 title: Authorization Adapter

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Authorization Adapter

Active Admin offers the ability to define and use your own authorization adapter. If implemented, the ‘#authorized?’ will be called when an action is taken. By default, ‘#authorized?’ returns true.

Setting up your own AuthorizationAdapter

The following example shows how to set up and tie your authorization adapter class to Active Admin:

“by

app/models/only_authors_authorization.rb

class OnlyAuthorsAuthorization < ActiveAdmin::AuthorizationAdapter

def authorized?(action, subject = nil) case subject when normalized(Post) # Only let the author update and delete posts if action == :update || action == :destroy subject.author == user else true end else true end end

end

“

In order to hook up OnlyAuthorsAuthorization to Active Admin, go to your application’s config/initializers/active_admin.rb and add/modify the line:

“by config.authorization_adapter = “OnlyAuthorsAuthorization”

“

Now, whenever a controller action is performed, the OnlyAuthorsAuthorization‘s #authorized? method will be called.

Authorization adapters can be configured per ActiveAdmin namespace as well, for example:

“

Getting Access to the Current User

From within your authorization adapter, you can call the #user method to retrieve the current user.

“by class OnlyAdmins < ActiveAdmin::AuthorizationAdapter

def authorized?(action, subject = nil) user.admin? end

end

“

Scoping Collections in Authorization Adapters

ActiveAdmin::AuthorizationAdapter also provides a hook method (#scope_collection) for the adapter to scope the resource’s collection. For example, you may want to centralize the scoping:

“by class OnlyMyAccount < ActiveAdmin::AuthorizationAdapter

def authorized?(action, subject = nil) subject.account == user.account end

def scope_collection(collection, action = Auth::READ) collection.where(account_id: user.account_id) end

end

“

All collections presented on Index Screens will be passed through this method and will be scoped accordingly.

Managing Access to Pages

Pages, just like resources, get authorized too. When authorizing a page, the subject will be an instance of ActiveAdmin::Page.

“by class OnlyDashboard < ActiveAdmin::AuthorizationAdapter def authorized?(action, subject = nil) case subject when ActiveAdmin::Page action == :read && subject.name == “Dashboard” && subject.namespace.name == :admin else false end end end

“

Action Types

By default Active Admin simplifies the controller actions into 4 actions:

:read - This controls if the user can view the menu item as well as the index and show screens.
:create - This controls if the user can view the new screen and submit the form to the create action.
:update - This controls if the user can view the edit screen and submit the form to the update action.
:destroy - This controls if the user can delete a resource.

Each of these actions is available as a constant. Eg: :read is available as ActiveAdmin::Authorization::READ.

Checking for Authorization in Controllers and Views

Active Admin provides a helper method to check if the current user is authorized to perform an action on a subject.

Use the #authorized?(action, subject) method to check.

“by

/app/views/admin/posts/_index_as_table.html.arb

index_table_for(collection, default_table_options) do |t| column :title column ‘’ do |post| link_to ‘Edit’, admin_post_path(post) if authorized? :update, post end end

“

If you are implementing a custom controller action, you can use the #authorize! method to raise an ActiveAdmin::AccessDenied exception.

“by class Admin::Post < ActiveAdmin::ResourceController

def publish post = Post.find(params[:id])

authorize! :publish, post
post.publish!

flash[:notice] = "Post has been published"
redirect_to [:admin, post]

end end

app/views/admin/posts/_action_item.html.arb

div(class: :action_items) do if params[:action] == ‘show’ if !post.published? && authorized?(:publish, post) action_link :publish, publish_admin_post_path(post), method: :post end end

end

“

Using the CanCan Adapter

Sub-classing ActiveAdmin::AuthorizationAdapter is fairly low level. Many times it’s nicer to have a simpler DSL for managing authorization. Active Admin provides an adapter out of the box for CanCan and CanCanCan.

To use the CanCan adapter, update the configuration in the Active Admin initializer:

“by config.authorization_adapter = ActiveAdmin::CanCanAdapter

“

You can also specify a method to be called on unauthorized access. This is necessary in order to prevent a redirect loop that can happen if a user tries to access a page they don’t have permissions for (see #2081).

“by config.on_unauthorized_access = :access_denied

“

The method access_denied would be defined in application_controller.rb. Here is one example that redirects the user from the page they don’t have permission to access to a resource they have permission to access (organizations in this case), and also displays the error message in the browser:

“by class ApplicationController < ActionController::Base protect_from_forgery

def access_denied(exception) redirect_to admin_organizations_path, alert: exception.message end end

“

By default this will use the ability class named “Ability”. This can also be changed from the initializer:

“by config.cancan_ability_class = “MyCustomAbility”

“

Now you can simply use CanCan or CanCanCan the way that you would expect and Active Admin will use it for authorization:

“by

app/models/ability.rb

class Ability include CanCan::Ability

def initialize(user) can :manage, Post can :read, User can :manage, User, id: user.id can :read, ActiveAdmin::Page, name: “Dashboard”, namespace_name: “admin” end

end

“

To view more details about the API’s, visit project pages of CanCan and CanCanCan.

Using the Pundit Adapter

Active Admin also provides an adapter out of the box for Pundit.

To use the Pundit adapter, update the configuration in the Active Admin initializer:

“by config.authorization_adapter = ActiveAdmin::PunditAdapter

“

Once that’s done, Active Admin will pick up your Pundit policies, and use them for authorization. For more information about setting up Pundit, see their documention.

Pundit also has verify_authorized and/or verify_policy_scoped methods to enforce usage of authorized and policy_scope. This conflicts with Active Admin’s authorization architecture, so if you’re using those features, you’ll want to disable them for Active Admin’s controllers:

“by class ApplicationController < ActionController::Base include Pundit after_action :verify_authorized, except: :index, unless: :active_admin_controller? after_action :verify_policy_scoped, only: :index, unless: :active_admin_controller?

def active_admin_controller? is_a?(ActiveAdmin::BaseController) end end

“

If you want to use batch actions, ensure that destroy_all? method is defined in your policy class. You can use this template policy in your application instead of default one generated by Pundit’s rails g pundit:install command.