active admin

ActiveAdmin's functionality is built on top of several 3rd party gems:

• Inherited Resources by Jose Valim (RESTful base controller class) inherited_resources
• Formtastic (DSL for creating forms). Note that the version used by AA is the 1.2 stable branch that works with both Rails 2.x and 3.x. formtastic
• Meta Search for implementing filters meta_search

Glossary

• Action Item - button displayed under the menu. The default action items are New, Edit and Delete.

Key components

• active_admin/dsl.rb - constitutes the AA public API. All the registration blocks are instance eval'd in this class.
• active_admin/resource.rb - abstraction provided by AA for wrapping the registered models. The instance of the current resource is available in ResourceController and views by calling the active_admin_config method.

Examples

Actions

Show action item only on certain pages:

# link to geocode promo
action_item :only => [:show, :edit] do
  link_to('Geocode', :action => :geocode, :id => resource.id)
end

Define action for individual records:

member_action :geocode, :method => :get do
  promo = Promo.find(params[:id])
  promo.geocode
  promo.save
  redirect_to :action => :edit, :notice => 'Promo geocoded'
end

Manually initialize and render an index table inside an .arb file:

config = ActiveAdmin::PageConfig.new(:as => :batch_table) do |instance|
  column :id
  column :title
  column :whatever
end

paginated_collection(collection, :entry_name => active_admin_config.resource_name) do
  div :class => 'index_content' do
    insert_tag(ActiveAdmin::Views::IndexAsTable, config, collection)
  end
end

Alternatively, use the config defined in the register block:

config = active_admin_config.page_configs[:index]

Filters

Add a filter to search by associated model's title (Author hasMany Posts):

ActiveAdmin.register Author do
    # for filters like this, :label and :as seem to be mandatory
    filter :posts_title, :label => "Author's Posts", :as => :string
end

Internals

ActiveAdmin gem defines an Engine class that extends Rails::Engine and allows the gem to behave like a Rails engine. One of the responsibilities of a Rails engine is to load models, controllers and helpers inside the app directory.

It also defines a set of paths, autoloaded when needed, that contain various classes that comprise ActiveAdmin.

Controllers

All AA controllers inherit from ApplicationController.

Scopes

ActiveAdmin.register_page "Translations" do

  content do
    # ActiveAdmin::Views::Pages::Page
  end
end

ActiveAdmin.register Design do

  form do |f|
    # ActiveAdmin::Views::Pages::Form
    # f is ActiveAdmin::FormBuilder

    f.inputs do
        # ActiveAdmin::Views::Pages::Form
    end
  end
end