Dynamic Select with ancestry

Question

My application using ancestry gem.

class Location < ActiveRecord::Base
 has_ancestry :cache_depth => true
 has_many :posts
end

class User < ActiveRecord::Base
 belongs_to :location
end

I created some random Location,

• Alaska
• California
  • Los Angeles
  • Fresno
    • Cincotta (Fresno)
    • Hammond (Fresno)
    • Melvin (Fresno)

My question if user sign up form if User select California, display child Los Angles and Fresno, after select Fresno then display it's child.

I got javascript tutorial for Dropdown list http://www.plus2net.com/javascript_tutorial/dropdown-list-demo.php

How is possible work with ancestry gem?

Answer 1

Nested

Firstly, if you wanted to keep them all in a single dropdown, we created the following helper which achieves it for you:

#app/helpers/application_helper.rb
def nested_dropdown(items)
    result = []
    items.map do |item, sub_items|
        result << [('- ' * item.depth) + item.name, item.id]
        result += nested_dropdown(sub_items) unless sub_items.blank?
    end
    result
end

This will allow you to call:

<%= f.select(:category_ids, nested_dropdown(Category.all.arrange), prompt: "Category", selected: @category ) %>

This will give you the ability to call a single dropdown, which has been nested according to your ancestry associations

--

Ajax

If you want to have double dropdown boxes, you'll probably have to implement an ajax function to pull the required data each time the initial dropdown changes:

#config/routes.rb
resources :categories do
    get :select_item
end

#app/assets/javascripts/application.js
$("#first_dropdown").on("change", function(){
   $.ajax({
       url: "categories/"+ $(this).val() + "/select_item",
       dataType: "json",
       success: function(data) {
          //populate second dropdown
       }
   })
});

#app/controllers/categories_controller.rb
Class CategoriesController < ApplicationController
    respond_to :json, only: :select_item

    def select_item
       category = @category.find params[:category_id]
       respond_with category.children
    end
end