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Connect a Rails app


In this tutorial, we’re going to create a simple Rails application named blog and connect it to a PlanetScale database. We’ll perform the initial migration from our local Rails application, and set up the database for future development.


pscale auth login

Create a Rails project

To connect a Rails application to a PlanetScale database, we start by creating a sample Rails project named blog and installing the libraries we'll need to connect to our PlanetScale database.

Open the command line and follow these steps:

  1. Create a Rails app named blog by running the following command:
rails new blog
  1. Change into the directory you just created, the blog Rails app:
cd blog
  1. Next, add the mysql2 gem to your Gemfile:
gem "mysql2"
  1. Then run bundle install

At this point, we have accomplished two things: we've created a Rails project called blog and installed the libraries that we'll need to connect to our PlanetScale database. Now it’s time to create a PlanetScale database.

Create a PlanetScale database and password

You can also create passwords in the PlanetScale application as documented here.

Using the CLI to create a connection string

  1. Using the pscale CLI, create a new database also named blog:
pscale database create blog
  1. Using the pscale CLI, create a new database password for the main branch of your database named blog:
pscale password create blog main development-password
  1. Take note of the values it returns to you.
Please save the values below as they will not be shown again
--------------------- -------- -------------- ----------------------------------- -------- ------------------ -------------------------------------------------------
development-password main c8ys5g3bbcdk writer Can Read & Write pscale_pw_wpSDL94q7HfBGa99Fev45tTjI5bqUxcqFKqAdUw3lFc

Configure Rails and PlanetScale

Let's set up our Rails application to talk to the new database.

  1. Open config/database.yml and configure the development database settings with your new credentials:
<<: *default
adapter: mysql2
database: blog
username: <USERNAME>
password: <PASSWORD>
ssl_mode: :verify_identity
sslca: "/etc/ssl/cert.pem"

The correct sslca path depends on your operating system and distribution. See CA root configuration for more information.

We're configuring the development Rails environment here for the sake of expedience. In actual use, the main database branch would typically serve the production environment.

Because this is a Rails app, we can also enable Automatic Rails migrations from the database's settings page.

Migrate your database

Here comes the fun stuff! Now that your application is configured to talk to PlanetScale, we can create our first migration.

  1. Create a Rails migration and call it CreateUsers:
rails generate migration CreateUsers

This rails command begins the migration for our table that is currently empty and generates a Ruby file that’ll be named something like this: db/migrate/20211014210422_create_users.rb

  1. We can fill in the body of this skeleton file with a few more relevant details, such as a user's name and email.
class CreateUsers < ActiveRecord::Migration[6.1]
def change
create_table :users do |t|
t.string :name
t.string :email
  1. Now let's run our migration:
bin/rails db:migrate
If you run into a proxy ERROR stating that address is already in use, run the following command: spring stop. (Spring is a Ruby library that pre-loads and runs all of our code into memory, detecting when our source code has changed.) Then, try the above command again.
  1. Now give it a whirl to make sure we can query the new table with our pscale CLI:
pscale shell blog main
blog/main> show tables;
| Tables_in_blog |
| ar_internal_metadata |
| schema_migrations |
| users |
blog/main> describe users;
| Field | Type | Null | Key | Default | Extra |
| id | bigint | NO | PRI | NULL | auto_increment |
| name | varchar(255) | YES | | NULL | |
| email | varchar(255) | YES | | NULL | |
| created_at | datetime(6) | NO | | NULL | |
| updated_at | datetime(6) | NO | | NULL | |

Promote your main branch to a production branch

A production branch is a highly available, protected database branch. Direct schema changes (CREATE, ALTER, and DELETE) are not allowed on production branches to prevent accidental data loss and must be applied via deploy requests.

pscale branch promote blog main

Congratulations! You're ready to develop your Rails application against PlanetScale.


In this tutorial, we created a simple Rails application named blog and connected it to a PlanetScale database.

Further reading

If you're interested in learning how to secure your application's connection to PlanetScale, please read Connecting to PlanetScale securely.

What's next?

Now that you've successfully connected your Rails app to PlanetScale, it's time to make more schema changes to your tables! Learn more about how PlanetScale allows you to make non-blocking schema changes to your database, or how to keep your schema_migrations table up-to-date between development and production branches with automatic schema migrations.

Need help?

Get help from PlanetScale's support team, or join our GitHub Discussion board to see how others are using PlanetScale.

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Last updated on January 20, 2022
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