Sinatra ActiveRecord Extension

Extends Sinatra with extension methods and Rake tasks for dealing with an SQL database using the ActiveRecord ORM.


Put it in your Gemfile, along with the adapter of your database. For simplicity, let's assume you're using SQLite:

gem "sinatra-activerecord"
gem "sqlite3"
gem "rake"

Now require it in your Sinatra application, and establish the database connection:

# app.rb
require "sinatra/activerecord"

set :database, {adapter: "sqlite3", database: "foo.sqlite3"}
# or set :database_file, "path/to/database.yml"

If you have a config/database.yml, it will automatically be loaded, no need to specify it. Also, in production, the $DATABASE_URL environment variable will automatically be read as the database (if you haven't specified otherwise).

Note that in modular Sinatra applications you will need to first register the extension:

class YourApplication < Sinatra::Base
  register Sinatra::ActiveRecordExtension

Now require the rake tasks and your app in your Rakefile:

# Rakefile
require "sinatra/activerecord/rake"

namespace :db do
  task :load_config do
    require "./app"

In the Terminal test that it works:

$ bundle exec rake -T
rake db:create            # Create the database from DATABASE_URL or config/database.yml for the current Rails.env (use db:create:all to create all dbs in the config)
rake db:create_migration  # Create a migration (parameters: NAME, VERSION)
rake db:drop              # Drops the database using DATABASE_URL or the current Rails.env (use db:drop:all to drop all databases)
rake db:fixtures:load     # Load fixtures into the current environment's database
rake db:migrate           # Migrate the database (options: VERSION=x, VERBOSE=false)
rake db:migrate:status    # Display status of migrations
rake db:rollback          # Rolls the schema back to the previous version (specify steps w/ STEP=n)
rake db:schema:dump       # Create a db/schema.rb file that can be portably used against any DB supported by AR
rake db:schema:load       # Load a schema.rb file into the database
rake db:seed              # Load the seed data from db/seeds.rb
rake db:setup             # Create the database, load the schema, and initialize with the seed data (use db:reset to also drop the db first)
rake db:structure:dump    # Dump the database structure to db/structure.sql
rake db:version           # Retrieves the current schema version number

And that's it, you're all set :)


You can create a migration:

$ bundle exec rake db:create_migration NAME=create_users

This will create a migration file in your migrations directory (./db/migrate by default), ready for editing.

class CreateUsers < ActiveRecord::Migration
  def change
    create_table :users do |t|
      t.string :name

Now migrate the database:

$ bundle exec rake db:migrate

You can also write models:

class User < ActiveRecord::Base
  validates_presence_of :name

You can put your models anywhere you want, only remember to require them if they're in a separate file, and that they're loaded after require "sinatra/activerecord".

Now everything just works:

get '/users' do
  @users = User.all
  erb :index

get '/users/:id' do
  @user = User.find(params[:id])
  erb :show

A nice thing is that the ActiveRecord::Base class is available to you through the database variable:

if database.table_exists?('users')
  # Do stuff
  raise "The table 'users' doesn't exist."


This gem was made in 2009 by Blake Mizerany, creator of Sinatra.


You can follow me on Twitter, I'm @jankomarohnic.