Connect a Ruby on Rails application to Neon Postgres

Ruby on Rails, also known simply as Rails, is an open-source web application framework written in Ruby. It uses a model-view-controller architecture, making it a good choice for developing database-backed web applications. This guide shows how to connect to a Ruby on Rails application to a Neon Postgres database.

To connect to Neon from a Ruby on Rails application:

1. Create a Neon Project
2. Create a Rails Project
3. Configure a PostgreSQL Database using Rails
4. Create a Rails Controller
5. Run the application

This guide was tested using Ruby v3.3.0 and Rails v7.1.2.

Create a Neon Project

If you do not have one already, create a Neon project.

1. Navigate to the Projects page in the Neon Console.
2. Click New Project.
3. Specify your project settings and click Create Project.

Create a Rails Project

Create a Rails project using the Rails CLI, and specify PostgreSQL as the database type:

gem install rails
rails new neon-with-rails --database=postgresql

You now have a Rails project in a folder named neon-with-rails.

Configure a PostgreSQL Database using Rails

Create a .env file in the root of your Rails project, and add the connection string for your Neon compute. Do not specify a database name after the forward slash in the connection string. Rails will choose the correct database depending on the environment.

DATABASE_URL=postgres://[user]:[password]@[neon_hostname]/

Create the development database by issuing the following commands from the root of your project directory:

# Load the DATABASE_URL into your session
source .env

# Create the development database
bin/rails db:create

Create a Rails Controller to Query the Database

Run the following command to create a controller and view. The controller will query the database version and supply it to the view file to render a web page that displays the PostgreSQL version.

rails g controller home index

Replace the controller contents at app/controllers/home_controller.rb with:

class HomeController < ApplicationController
  def index
    @version = ActiveRecord::Base.connection.execute("SELECT version();").first['version']
  end
end

Replace the contents of the view file at app/views/home/index.html.erb with:

<% if @version %>
  <p><%= @version %></p>
<% end %>

Replace the contents of config/routes.rb with the following code to serve your home view as the root page of the application:

Rails.application.routes.draw do.
  get "up" => "rails/health#show", as: :rails_health_check

  # Defines the root path route ("/")
  root 'home#index'
end

Run the application

Start the application using the Rails CLI from the root of the project:

bin/rails server -e development

Visit localhost:3000/ in your web browser. Your Neon database's Postgres version will be displayed. For example:

PostgreSQL 15.5 on x86_64-pc-linux-gnu, compiled by gcc (Debian 10.2.1-6) 10.2.1 20210110, 64-bit