(Ruby on Rails6) Creating a database and displaying it in a view

Machine spec / version

-Version 10.15.3 ・ Ruby ruby 2.6.3p62 ・ Rails


In this article, I will record the creation of the database in Ruby on Rails6 and the display in the view as an oblivion. If you are having trouble creating a database, I hope you find it useful.


Here, we will start by creating a directory. The database creation will be described later, so if you know it, you can skip it!

Creating a directory

Enter the following command in any directory. Also, since it is supposed to be deployed on heroku, the database (postgresql) is set.


rails new directory name-TB --database=postgresql

rails new form_test -TB --database=postgresql

If you don't have a database to set, you can use the following command.


rails new directory name

rails new form_test

Creating a page

Let's move to the directory you just created and create a page.


cd directory name

(Example ↓)
cd form_test


rails generate controller arbitrary name index

rails generate controller Forms index

For "index", change the input name with the intention of creating it. There is no problem with the abbreviated command of generate → g. Also, the directory name should be pluralized, such as "Forms", for easier management later.


rails g controller arbitrary name index

rails g controller Forms index

routes settings

If you set the following to routes, it will be set to http: // localhost: 3000 / forms.


Rails.application.routes.draw do
  # get "Arbitrary name" => "Arbitrary value#index"
    get "forms" => "forms#index"
  # For details on the DSL available within this file, see https://guides.rubyonrails.org/routing.html

Check with browser

I will check it with a browser once. Enter the command to display in the browser.


rails s
rails server

Was it displayed?

Also, I wrote it in postgresql directory creation, but I may get an error (I got an error) In that case, enter the following command.


rails db:create

The cause of the error will be explained in another article.

Prepare the database

From here, we will create the database.

Create database


rails g model database name content:text
rails g model Forms content:text

Database names are easier to manage with the initial "uppercase" and "plural". Not omitted ↓ But OK


rails generate model database name content:text
rails generate model Forms content:text

Database migration

After creating the database, please migrate. If you forget it, you will get an error when checking in your browser.


rails db:migrate

Added database post

Instantiate. To do this, type rails console first in the command.


rails console

Arbitrary name=Database name.new(content: "I'm studying Rails at Progate from today!")
Arbitrary name.save

form1 = Form.new(content: "test")

As an aside, if you enter ↓ when creating a directory, it will be "forms (plural form)", so it is better to set it to "form (singular form)" when adding a database.


rails generate controller forms index

Save database posts

After adding a post, please save. By doing this, your post will be saved.


Arbitrary name.save



quit is the command to exit the rails console. You can save multiple posts by repeating this process 2 ~.

Get database posts


This time i"Directory name=Database name.all"Is used.

Directory name=Database name.all
forms = Form.all
→ Get all values

Directory name[0]
→ Get the first value

Directory name[0].content
→ Initial value(content)Get

That's all for creating the database. Next, we will work on displaying it in the view.

Save database contents to view

Control settings

You can get all the posted contents by setting "directory name = database name.all" used for fetching the database in controller.

Also, in Ruby, "form" must have an @ like "@form".


class PostsController < ApplicationController
  def index
  # @Directory name=Database name.all
    @forms = Form.all

View settings and Each array


<p>Find me in app/views/forms/index.html.erb</p>
 <% @Directory name.each do |form| %>
     <%=Singular form of directory name.content %>
  <% end %>

Example ↓


<p>Find me in app/views/forms/index.html.erb</p>
 <% @forms.each do |form| %>
        <%= form.content %>
 <% end %>

Iterative processing by Each


 <% @forms.each do |form| %>
 <% end %>

You can iterate by using each. Also


<%= form.content %>

Is displaying the "contents" of the database.

And, please note that in Ruby, different behavior occurs due to the difference in the notation of ↓. Here, we want to display the contents of the database, so enter <% = form.content%>.


<%= form.content %>
→ Display the character string in the view(=Important)

<% form.content %>
→ Do not display the result of the character string in the view

Check with browser

rails_db-test.png If there is no problem, you can check it at the route destination. I tried to display test1 and test2 in the test.

The above tests are published on Github. If you want to try it, please download it.



Thank you for reading this far. That's all for creating a database and displaying it in a view in Ruby on Rails6. The routes and controller settings are complicated and a little tiring, but I hope they are displayed in the view.

Reference link

Books: <a href="https://www.amazon.co.jp/%E3%81%9F%E3%81%AE%E3%81%97%E3%81%84Ruby-%E7%AC%AC6 % E7% 89% 88-Informatics-IDEA-% E9% AB% 98% E6% A9% 8B / dp / 4797399848 / ref = sr_1_1? __mk_ja_JP =% E3% 82% AB% E3% 82% BF% E3% 82 % AB% E3% 83% 8A & dchild = 1 & keywords =% E3% 81% 9F% E3% 81% AE% E3% 81% 97% E3% 81% 84Ruby +% E7% AC% AC6% E7% 89% 88 & qid = 1600088731 & s = books & sr = 1-1 "target =" blank "> Fun Ruby 6th Edition

My link

Also, there is a link to the Twitter portfolio, so if you are interested, Please connect. I would be very happy to have friends who can share programming learning.

Twitter Portfolio Github

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