Connecting your Rails application to a database #

Rails default setup uses sqlite which is a great way to get starting building applications, but at some point we will need to connect to a real database. Whether you need functionality that is specific to a certain database, or you want to simulate your production environment more. Connecting to a database is pretty easy with Rails. The first thing you will need is a database installed on your computer. For my apps I primarily use Postgres and pgAdmin as my GUI.

First we will also want to add a gem for Postgres in our Gemfile

gem ‘pg’

Then run the command bundle install. Next in our Rails app we want to update the database.yml file in the config directory. There is four sections, default, development, test, and production. For a basic configuration set the default and any changes you may need in the different environments can be overridden.

default: &default
  adapter: postgresql
  encoding: unicode
  username: postgres
  password: postgres
  pool: 5
  timeout: 5000
  host: 127.0.0.1

development:
  <<: *default
  database: TestApp

test:
  <<: *default
  database: TestApp_test

production:
  <<: *default
  database: <%= ENV['POSTGRES_DB'] %>

Let’s break down this file a little. The default is where most of the key information is at. I have the username and password set to postgres, but for a real application you would want to put these into environment variables. The host is the IP address for your database. The other environments have a line <<: *default which pulls the config options from the default section. If you need to change anything for these environments do so after that line.