Displaing closure_tree in ActiveAdmin. How to create hierarhical view?

At minimal I want to achieve some indentation in index table. Like this:

+Parent
+--Child
   +--Child of Child
+--Child

So I create the following:

ActiveAdmin.register Section do
  config.filters = false

  index do
    column :name do |s|
      " #{ "――" * s.depth } #{s.name}"
    end
    default_actions
  end

  controller do
    def collection
      Section.some_method_to_get_things_in_right_order
    end
  end
end

It's need to some_method return active record relation, but I haven't succeed. And ended up with this hacky way.

The sortable_tree activeadmin plugin works for me well with closure tree.

https://github.com/zorab47/active_admin-sortable_tree

It creates a simple hierarchical and sortable view.

Just put the following in your tree model resource (app/admin/TreeModel): (assuming Rails >4, replace <..> with your values)

ActiveAdmin.register TreeModel do

config.filters = false # the default filters don't work unfortunately
permit_params <YOUR_TREE_MODEL_ATTRIBUTES>

sortable tree: true,
               sorting_attribute: :<YOUR_SORT_ATTRIBUTE>,
               parent_method: :parent,
               children_method: :children,
               roots_method: :roots

index :as => :sortable do
    label :name # item content
        actions
  end

end