Utilization of Active Hash

Introduction

I am making an original app with Rails. I applied Active Hash to this app. Enabled to select the data set in ActiveHash in pull-down format. I will write it down so that I can remember it even if I forget it.

• Active Hash handles data that does not change, such as a list of prefecture names. Since it is data that does not change, it is not necessary to save it directly in the database (id prepared for each prefecture is saved).

Development environment ruby 2.6.5 Rails 6.0.3.4

table of contents

1. Introduction of Active Hash
2. Model preparation
3. Controller preparation
4. View view

1. Introduction of Active Hash

Active Hash is one of the Gem. Add to the Gem file and install in the terminal.

Gemfile

gem 'active_hash'

Terminal

bundle install

2. Model preparation

Here, day is the target of Active Hash. When creating a model-If skip-migration is added, the migration file will not be created. If there are other ActiveHash targets, create as many models as there are.

Terminal

rails g model day --skip-migration

Inherit ActiveHash in the model. self.data is an array that stores hash format data. In the hash, id and name (days) are linked.

app/models/day.rb

class day < ActiveHash::Base #← Inherit ActiveHash
 self.data = [
   { id: 1, name: '--' },
   { id: 2, name: '1 day' },
   { id: 3, name: '1 week' },
 ]
 end

Next, set to save the id of the number of days set above in the database. Take article as an example of the table to which ActiveHash is linked.

2020***********_create_articles.rb

class CreateArticles < ActiveRecord::Migration[6.0]
 def change
   create_table :articles do |t|
     t.string     :title        , null: false
     t.text       :text         , null: false
     t.integer    :day_id       , null: false #Column where ActiveHash id is stored
     t.timestamps
   end
 end
end

Don't forget to migrate. Model associations too.

app/model/article

validates :day_id # _Add id
belongs_to_active_hash :day # _no id required

3. Controller preparation

Add day_id to the strong parameter so that it can be saved.

ruby:article.controller.rb

Example:
  def new    
    @article = Article.new
  end

  def create    
    @article = Article.new(article_params)
  end

  private
  def article_params
    params.require(:article).permit(:title, :text, :day_id)
  end

View view

It can be displayed in pull-down format by collection_select. The arguments are from 1st to 5th.

<%= f.collection_select(:day_id, Day.all, :id, :name, {}, {class:"day-select"}) %>

that's all