class Membership < ActiveRecord::Base
  belongs_to :course
  belongs_to :person

class Course < ActiveRecord::Base
  has_many :memberships
  has_many :people,  :through => :memberships

class Person < ActiveRecord::Base
  has_many :memberships
  has_many :courses, :through => :memberships

form do |f|
  f.inputs

  f.has_many :associations do |association|
     association.inputs
  end

  f.buttons
end

class Ingredient < ActiveRecord::Base
has_and_belongs_to_many :products, :join_table => :ingredients_products
end

class Product < ActiveRecord::Base
  has_and_belongs_to_many :ingredients, :join_table => :ingredients_products
end

class CreateProductsIngredients < ActiveRecord::Migration
  def self.up
    create_table :ingredients_products,:id => false do |t|
      t.integer :product_id
      t.integer :ingredient_id
      t.timestamps
    end
  end

  def self.down
    drop_table :products_ingredients
  end
end

ActiveAdmin.register Product do
  form do |f|
        f.inputs "Details" do
          f.input :product_name
          f.input :brand
          f.input :ingredients # don't forget this one!
        end
end

ActiveAdmin.register User do
    index do
        column :id
        column :name
        column :attendance
        column :person do |membership|
            membership.person.name
        end
        column :course do |membership|
            membership.course.name
        end
        default_actions
    end

    form do |f|
        f.inputs "Membership" do
            f.input :name
            f.input :created_at
            f.input :updated_at
        end
        f.inputs :name => "Person", :for => :person do |person|
            person.inputs
        end
        f.inputs :name => "Course", :for => :course do |course|
            course.input :name
        end
        f.buttons
    end
end