[RUBY] [Rails] New app creation --Notes--

Create new app

After moving to the directory you want to create


rails new [app name] -d mysql

Specify mysql when creating database with "-d mysql"

Database creation

Move to the created app directory. The following command will create the database according to the settings described in database.yml.


rake db:create

If it doesn't work as expected, check database.yml. Since sqlite is specified in the initial database, if necessary, write mysql in gem and bundle install.

Reference: Let's develop Rails applications! ~ Development Preparation ~

Creating a controller


rails g controller [Controller name]

Routing settings


root "[Controller name]#index"

When root accesses with url, the controller and action displayed on the top page are displayed. This time, the [index] action is specified.

Controller action description

I will describe the necessary actions.

[Controller name]_controller.rb

def index

View file creation

Since the [app/views/controller name /] directory has been created, create the index.html.erb file.


<p>Hello, World!</p>

Here, when you start the rails server and access it locally, "Hello, World!" Is displayed.

Create table


rails g model [Model name]

When you create a model, a migration file for creating a table is automatically generated. Describe the migration file and execute the migration file.


rails db:migrate

Reference Active Record Migration Reference Rails Migration Basic Summary

that's all.

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