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

   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.

2. 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.

3. 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=postgresql://[user]:[password]@[neon_hostname]/

   note

   You can find the connection string for your database by clicking the Connect button on your Project Dashboard. For more information, see Connect from any application.

   important

   The role you specified in the DATABASE_URL must have CREATEDB privileges. Roles created in the Neon Console, CLI, or API, including the default role created with a Neon project, are granted membership in the neon_superuser role, which has the CREATEDB privilege. Alternatively, you can create roles with SQL to grant specific privileges. See Manage database access.

   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

4. 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

5. 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

Schema migration with Ruby on Rails

For schema migration with Ruby on Rails, see our guide:

• Ruby on Rails Migrations

  Schema migration with Neon Postgres and Ruby on Rails