```ruby
ActiveAdmin.register Category do

  filter :identifier

  permit_params do
    %i(identifier)
  end

  controller do
    # For some reason, inherited resource update does not work.
    def update
      region = resource
      region.update_attributes(params[:category][:id])
      super
    end
  end

  index do
    selectable_column
    column :id
    column :identifier
    column :name, :sortable => false
    actions
  end
end
```

Use activeadmin's `permitted_params` method inside controller
user
```ruby
ActiveAdmin.register Category do

  filter :identifier

  permit_params do
    %i(identifier)
  end

  controller do
    # For some reason, inherited resource update does not work.
    def update
      region = resource
      region.update_attributes(permitted_params[:category])
      super
    end
  end

  index do
    selectable_column
    column :id
    column :identifier
    column :name, :sortable => false
    actions
  end
end
```
assistant