(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 6.0.3.2

Preface

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.

Preparation

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.

terminal

rails new directory name-TB --database=postgresql

(Example)↓
rails new form_test -TB --database=postgresql

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

terminal

rails new directory name

(Example)↓
rails new form_test

• If set with postgresql, an error will occur when the browser is displayed. The process will be described later.

Creating a page

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

terminal

cd directory name

(Example ↓)
cd form_test

terminal

rails generate controller arbitrary name index

(Example)↓
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.

terminal

rails g controller arbitrary name index

(Example)↓
rails g controller Forms index

routes settings

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

config/routes

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
end

Check with browser

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

terminal

rails s
or
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.

terminal

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

terminal

rails g model database name content:text
(Example)↓
rails g model Forms content:text

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

terminal

rails generate model database name content:text
(Example)↓
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.

terminal

rails db:migrate

Added database post

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

terminal

rails console

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

(Example)↓
form1 = Form.new(content: "test")
form1.save

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.

terminal

rails generate controller forms index

Save database posts

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

terminal

Arbitrary name.save

(Example)↓
form1.save

quit

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

Get database posts

terminal

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

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

Directory name[0]
forms[0]
→ Get the first value

Directory name[0].content
forms[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".

app/controllers/Any_controller.rb

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

View settings and Each array

rb:app/views/Any/index.html.erb

<h1>Forms#index</h1>
<p>Find me in app/views/forms/index.html.erb</p>
　<% @Directory name.each do |form| %>
      <div>
　　　　　<%=Singular form of directory name.content %>
      </div>
  <% end %>

Example ↓

rb:app/views/Any/index.html.erb

<h1>Forms#index</h1>
<p>Find me in app/views/forms/index.html.erb</p>
 <% @forms.each do |form| %>
      <div>
        <%= form.content %>
      </div>
 <% end %>

Iterative processing by Each

rb:app/views/Any/index.html.erb

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

You can iterate by using each. Also

rb:app/views/Any/index.html.erb

<%= 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%>.

rb:app/views/Any/index.html.erb

<%= 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

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.

→Github

Afterword

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

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