Working with Resources

Every Active Admin resource corresponds to a Rails model. So before creating a resource you must first create a Rails model for it.

Create a Resource

The basic command for creating a resource is rails g active_admin:resource Post. The generator will produce an empty app/admin/post.rb file like so:

ActiveAdmin.register Post do
  # everything happens here :D
end

Setting up Strong Parameters

Rails 4 replaces attr_accessible with Strong Parameters, which moves attribute whitelisting from the model to the controller.

Use the permit_params method to define which attributes may be changed:

ActiveAdmin.register Post do
  permit_params :title, :content, :publisher_id
end

Any form field that sends multiple values (such as a HABTM association, or an array attribute) needs to pass an empty array to permit_params:

ActiveAdmin.register Post do
  permit_params :title, :content, :publisher_id, roles: []
end

Nested associations in the same form also require an array, but it needs to be filled with any attributes used.

ActiveAdmin.register Post do
  permit_params :title, :content, :publisher_id,
    tags_attributes: [:id, :name, :description, :_destroy]
end

# Note that `accepts_nested_attributes_for` is still required:
class Post < ActiveRecord::Base
  accepts_nested_attributes_for :tags, allow_destroy: true
end

If you want to dynamically choose which attributes can be set, pass a block:

ActiveAdmin.register Post do
  permit_params do
    params = [:title, :content, :publisher_id]
    params.push :author_id if current_user.admin?
    params
  end
end

The permit_params call creates a method called permitted_params. You should use this method when overriding create or update actions:

ActiveAdmin.register Post do
  controller do
    def create
      # Good
      @post = Post.new(permitted_params[:post])
      # Bad
      @post = Post.new(params[:post])

      if @post.save
        # ...
      end
    end
  end
end

Disabling Actions on a Resource

All CRUD actions are enabled by default. These can be disabled for a given resource:

ActiveAdmin.register Post do
  actions :all, except: [:update, :destroy]
end

Rename the Resource

By default, any references to the resource (menu, routes, buttons, etc) in the interface will use the name of the class. You can rename the resource by using the :as option.

ActiveAdmin.register Post, as: "Article"

The resource will then be available at /admin/articles.

Customize the Namespace

We use the admin namespace by default, but you can use anything:

# Available at /today/posts
ActiveAdmin.register Post, namespace: :today

# Available at /posts
ActiveAdmin.register Post, namespace: false

Customize the Menu

The resource will be displayed in the global navigation by default. To disable the resource from being displayed in the global navigation:

ActiveAdmin.register Post do
  menu false
end

The menu method accepts a hash with the following options:

• :label - The string or proc label to display in the menu. If it's a proc, it will be called each time the menu is rendered.
• :parent - The string id (or label) of the parent used for this menu
• :if - A block or a symbol of a method to call to decide if the menu item should be displayed
• :priority - The integer value of the priority, which defaults to 10

Labels

To change the name of the label in the menu:

ActiveAdmin.register Post do
  menu label: "My Posts"
end

If you want something more dynamic, pass a proc instead:

ActiveAdmin.register Post do
  menu label: proc{ I18n.t "mypost" }
end

Menu Priority

Menu items are sorted first by their numeric priority, then alphabetically. Since every menu by default has a priority of 10, the menu is normally alphabetical.

You can easily customize this:

ActiveAdmin.register Post do
  menu priority: 1 # so it's on the very left
end

Conditionally Showing / Hiding Menu Items

Menu items can be shown or hidden at runtime using the :if option.

ActiveAdmin.register Post do
  menu if: proc{ current_user.can_edit_posts? }
end

The proc will be called in the context of the view, so you have access to all your helpers and current user session information.

Drop Down Menus

In many cases, a single level navigation will not be enough to manage a large application. In that case, you can group your menu items under a parent menu item.

ActiveAdmin.register Post do
  menu parent: "Blog"
end

Note that the "Blog" parent menu item doesn't even have to exist yet; it can be dynamically generated for you.

Customizing Parent Menu Items

All of the options given to a standard menu item are also available to parent menu items. In the case of complex parent menu items, you should configure them in the Active Admin initializer.

# config/initializers/active_admin.rb
config.namespace :admin do |admin|
  admin.build_menu do |menu|
    menu.add label: 'Blog', priority: 0
  end
end

# app/admin/post.rb
ActiveAdmin.register Post do
  menu parent: 'Blog'
end

Dynamic Parent Menu Items

While the above works fine, what if you want a parent menu item with a dynamic name? Well, you have to refer to it by its :id.

# config/initializers/active_admin.rb
config.namespace :admin do |admin|
  admin.build_menu do |menu|
    menu.add id: 'blog', label: proc{"Something dynamic"}, priority: 0
  end
end

# app/admin/post.rb
ActiveAdmin.register Post do
  menu parent: 'blog'
end

Adding Custom Menu Items

Sometimes it's not enough to just customize the menu label. In this case, you can customize the menu for the namespace within the Active Admin initializer.

# config/initializers/active_admin.rb
config.namespace :admin do |admin|
  admin.build_menu do |menu|
    menu.add label: "The Application", url: "/", priority: 0

    menu.add label: "Sites" do |sites|
      sites.add label: "Google",   url: "http://google.com", html_options: { target: :blank }
      sites.add label: "Facebook", url: "http://facebook.com"
      sites.add label: "Github",   url: "http://github.com"
    end
  end
end

This will be registered on application start before your resources are loaded.

Scoping the queries

If your administrators have different access levels, you may sometimes want to scope what they have access to. Assuming your User model has the proper has_many relationships, you can simply scope the listings and finders like so:

ActiveAdmin.register Post do
  scope_to :current_user # limits the accessible posts to `current_user.posts`

  # Or if the association doesn't have the default name:
  scope_to :current_user, association_method: :blog_posts

  # Finally, you can pass a block to be called:
  scope_to do
    User.most_popular_posts
  end
end

You can also conditionally apply the scope:

ActiveAdmin.register Post do
  scope_to :current_user, if:     proc{ current_user.limited_access? }
  scope_to :current_user, unless: proc{ current_user.admin? }
end

Eager loading

A common way to increase page performance is to elimate N+1 queries by eager loading associations:

ActiveAdmin.register Post do
  includes :author, :categories
end

Customizing resource retrieval

If you need to customize the collection properties, you can overwrite the scoped_collection method.

ActiveAdmin.register Post do
  controller do
    def scoped_collection
      end_of_association_chain.where(visibility: true)
    end
  end
end

If you need to completely replace the record retrieving code (e.g., you have a custom to_param implementation in your models), override the resource method on the controller:

ActiveAdmin.register Post do
  controller do
    def find_resource
      Post.where(id: params[:id]).first!
    end
  end
end

Our controllers are built on Inherited Resources, so you can use all of its features.

Belongs To

It's common to want to scope a series of resources to a relationship. For example a Project may have many Milestones and Tickets. To nest the resource within another, you can use the belongs_to method:

ActiveAdmin.register Project
ActiveAdmin.register Ticket do
  belongs_to :project
end

Projects will be available as usual and tickets will be availble by visiting /admin/projects/1/tickets assuming that a Project with the id of 1 exists. Active Admin does not add "Tickets" to the global navigation because the routes can only be generated when there is a project id.

To create links to the resource, you can add them to a sidebar (one of the many possibilities for how you may with to handle your user interface):

ActiveAdmin.register Project do

  sidebar "Project Details", only: [:show, :edit] do
    ul do
      li link_to "Tickets",    admin_project_tickets_path(project)
      li link_to "Milestones", admin_project_milestones_path(project)
    end
  end
end

ActiveAdmin.register Ticket do
  belongs_to :project
end

ActiveAdmin.register Milestone do
  belongs_to :project
end

In some cases (like Projects), there are many sub resources and you would actually like the global navigation to switch when the user navigates "into" a project. To accomplish this, Active Admin stores the belongs_to resources in a seperate menu which you can use if you so wish. To use:

ActiveAdmin.register Ticket do
  belongs_to :project
  navigation_menu :project
end

ActiveAdmin.register Milestone do
  belongs_to :project
  navigation_menu :project
end

Now, when you navigate to the tickets section, the global navigation will only display "Tickets" and "Milestones". When you navigate back to a non-belongs_to resource, it will switch back to the default menu.

You can also defer the menu lookup until runtime so that you can dynamically show different menus, say perhaps based on user permissions. For example:

ActiveAdmin.register Ticket do
  belongs_to :project
  navigation_menu do
    authorized?(:manage, SomeResource) ? :project : :restricted_menu
  end
end

If you still want your belongs_to resources to be available in the default menu and through non-nested routes, you can use the :optional option. For example:

ActiveAdmin.register Ticket do
  belongs_to :project, optional: true
end