Let's make a pseudo model using active_hash ~ Prefecture data ~

Creating a certain Mercari copy site active_hash

You can create a pseudo model and store data without creating a database

So I will try using a gem called active_hash

First add active_hash to Gemfile

gem 'active_hash'

bundle install

Model I'm making a model file with Do not create with rails g model this time

I usually inherit ApplicationRecord, It seems that models that use active_hash need to inherit ActiveHash :: Base.

So I will create it directly in app / models /

prefecture.rb

class Prefecture < ActiveHash::Base

end

Inherit ActiveHash :: Base like this

The data template looks like this

prefecture.rb

class Prefecture < ActiveHash::Base

  self.data = [ ]

end

I will put the data in this

prefecture.rb

class Prefecture < ActiveHash::Base

  self.data = [
      {id: 1, name: 'Hokkaido'}, {id: 2, name: 'Aomori Prefecture'}, {id: 3, name: 'Iwate Prefecture'},
      {id: 4, name: 'Miyagi Prefecture'}, {id: 5, name: 'Akita'}, {id: 6, name: 'Yamagata Prefecture'},
      {id: 7, name: 'Fukushima Prefecture'}, {id: 8, name: 'Ibaraki Prefecture'}, {id: 9, name: 'Tochigi Prefecture'},
      {id: 10, name: 'Gunma Prefecture'}, {id: 11, name: 'Saitama'}, {id: 12, name: 'Chiba'},
      {id: 13, name: 'Tokyo'}, {id: 14, name: 'Kanagawa Prefecture'}, {id: 15, name: 'Niigata Prefecture'},
      {id: 16, name: 'Toyama Prefecture'}, {id: 17, name: 'Ishikawa Prefecture'}, {id: 18, name: 'Fukui prefecture'},
      {id: 19, name: 'Yamanashi Prefecture'}, {id: 20, name: 'Nagano Prefecture'}, {id: 21, name: 'Gifu Prefecture'},
      {id: 22, name: 'Shizuoka Prefecture'}, {id: 23, name: 'Aichi prefecture'}, {id: 24, name: 'Mie Prefecture'},
      {id: 25, name: 'Shiga Prefecture'}, {id: 26, name: 'Kyoto'}, {id: 27, name: 'Osaka'},
      {id: 28, name: 'Hyogo prefecture'}, {id: 29, name: 'Nara Prefecture'}, {id: 30, name: 'Wakayama Prefecture'},
      {id: 31, name: 'Tottori prefecture'}, {id: 32, name: 'Shimane Prefecture'}, {id: 33, name: 'Okayama Prefecture'},
      {id: 34, name: 'Hiroshima Prefecture'}, {id: 35, name: 'Yamaguchi Prefecture'}, {id: 36, name: 'Tokushima Prefecture'},
      {id: 37, name: 'Kagawa Prefecture'}, {id: 38, name: 'Ehime Prefecture'}, {id: 39, name: 'Kochi Prefecture'},
      {id: 40, name: 'Fukuoka Prefecture'}, {id: 41, name: 'Saga Prefecture'}, {id: 42, name: 'Nagasaki Prefecture'},
      {id: 43, name: 'Kumamoto Prefecture'}, {id: 44, name: 'Oita Prefecture'}, {id: 45, name: 'Miyazaki prefecture'},
      {id: 46, name: 'Kagoshima prefecture'}, {id: 47, name: 'Okinawa Prefecture'}
  ]

end

I will put it in hash format like this
Next association

product.rb

class product < ApplicationRecord

  extend ActiveHash::Associations::ActiveRecordExtensions
  belongs_to_active_hash :prefecture

end

This time it will be linked with the product table, so describe it in product.rb

Usually belongs_to, but in the case of active_hash it will be belongs_to_active_hash

prefecture.rb

class Prefecture < ActiveHash::Base

  self.data = [
      {id: 1, name: 'Hokkaido'}, {id: 2, name: 'Aomori Prefecture'}, {id: 3, name: 'Iwate Prefecture'},
      {id: 4, name: 'Miyagi Prefecture'}, {id: 5, name: 'Akita'}, {id: 6, name: 'Yamagata Prefecture'},
      {id: 7, name: 'Fukushima Prefecture'}, {id: 8, name: 'Ibaraki Prefecture'}, {id: 9, name: 'Tochigi Prefecture'},
      {id: 10, name: 'Gunma Prefecture'}, {id: 11, name: 'Saitama'}, {id: 12, name: 'Chiba'},
      {id: 13, name: 'Tokyo'}, {id: 14, name: 'Kanagawa Prefecture'}, {id: 15, name: 'Niigata Prefecture'},
      {id: 16, name: 'Toyama Prefecture'}, {id: 17, name: 'Ishikawa Prefecture'}, {id: 18, name: 'Fukui prefecture'},
      {id: 19, name: 'Yamanashi Prefecture'}, {id: 20, name: 'Nagano Prefecture'}, {id: 21, name: 'Gifu Prefecture'},
      {id: 22, name: 'Shizuoka Prefecture'}, {id: 23, name: 'Aichi prefecture'}, {id: 24, name: 'Mie Prefecture'},
      {id: 25, name: 'Shiga Prefecture'}, {id: 26, name: 'Kyoto'}, {id: 27, name: 'Osaka'},
      {id: 28, name: 'Hyogo prefecture'}, {id: 29, name: 'Nara Prefecture'}, {id: 30, name: 'Wakayama Prefecture'},
      {id: 31, name: 'Tottori prefecture'}, {id: 32, name: 'Shimane Prefecture'}, {id: 33, name: 'Okayama Prefecture'},
      {id: 34, name: 'Hiroshima Prefecture'}, {id: 35, name: 'Yamaguchi Prefecture'}, {id: 36, name: 'Tokushima Prefecture'},
      {id: 37, name: 'Kagawa Prefecture'}, {id: 38, name: 'Ehime Prefecture'}, {id: 39, name: 'Kochi Prefecture'},
      {id: 40, name: 'Fukuoka Prefecture'}, {id: 41, name: 'Saga Prefecture'}, {id: 42, name: 'Nagasaki Prefecture'},
      {id: 43, name: 'Kumamoto Prefecture'}, {id: 44, name: 'Oita Prefecture'}, {id: 45, name: 'Miyazaki prefecture'},
      {id: 46, name: 'Kagoshima prefecture'}, {id: 47, name: 'Okinawa Prefecture'}
  ]

  include ActiveHash::Associations
  has_many :users

end

The prefecture side is like this

All you have to do is display it! !!