Sinatra ActiveRecord Extension

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

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ActiveRecord >= 4.1


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).

If both config/database.yml and $DATABASE_URL are present, the database configuration of this two will be merged, with $DATABASE_URL's variable taking precedence over database.yml (for the same variable / key).

Note: If you are using ActiveRecord 6.0 and above, and have defined multiple databases for the database.yml, the $DATABASE_URL configuration will be discarded, following Active Record convention here.

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 Janko on Twitter, @jankomarohnic. You can follow Axel on Twitter, @soulchildpls.