ActiveAdmin中的自定义过滤器

Question

How do I implement custom filtering in ActiveAdmin? It should be based on ActiveRecord conditions.

Eg I have 2 models: Product and Category

class Product < ActiveRecord::Base
   belongs_to :category
   scope :in_category, ->(category_id) { where(category_id: Category.find(category_id).descendants.pluck(:id)) }
end

class Category < ActiveRecord::Base
   has_many :products
   acts_as_nested_set
end

ActiveAdmin.register Product do
  filter :category
end

Categories are hierarchical.

When I enter category in filter I should see all products of that category and it's descendant categories (in_category scope in Product model).

Now ActiveAdmin uses ransack instead of metasearch and oldest approaches does not work.

Answer 1

Solution for my example.

In Product model:

ransacker :containing_category, 
          :formatter => ->(v) { ids = Category.find(v).self_and_descendants.pluck(:id);
                                ids.present? ? ids : nil } do |product|
  product.table[:category_id]
end

Filter:

filter :containing_category_in, 
  as: :select, 
  label: 'Category',
  collection: Category.all

Answer 2

Here is article how to create a custom column on index page in ActiveAdmin and add custom filter based on Ransack:

http://codeonhill.com/activeadmin-custom-column-and-its-filter/