ServiceRecord

An ActiveRecord lookalike but for business model requirements, a.k.a Service Objects.

Rails is packed with amazing tools to get you started with building your new awesome project and enforces reliable and battle-tested guidelines. One of those guideline is "thin controllers and fat models", but sometimes (actually most of the time) its difficult to follow because most business requirements are not that simple like most CRUD operations.

Enters, ServiceRecord, a tiny wrapper around basic goodies included in Rails. Its similar to ActiveRecord models but their sole purpose is to perform a big/complex/muilt-step task without bloating the controllers or models.

Add this line to your application's Gemfile:

gem 'service_record'

And then execute:

$ bundle install

Or install it yourself as:

$ gem install service_record

Now you can start creating new service classes. Rails generator can be used to create new services, e.g, the following will create a service class file app/services/authenticate_user.rb.

rails g service authenticate_user

A basic Service class looks like the following

class MyService < ApplicationService
  attribute :email, :string
  attribute :password, :string

  validates :email, :password, presence: true

  def perform
  end
end

Now you can invoke this service by writting;

response = MyService.perform(email: '', password: '')

The returned response from a service will have the following useful attributes/methods,

• success? contains true if service was performed without any errors, false otherwise
• failure? contains opposite of success?
• result contains returned value of service perform function
• errors contains details about issues that occurr while performing the service

There is also a perform! (with a bang !) method which will raise ServiceRecord::Failure in case of service failure.

Let's take a real world example of users controller and the sign_in action that involes JWT authentication.

Without ServiceRecord 🙈

# Inside controllers/users_controller.rb
def sign_in
  token = nil
  errors = []

  # Basic validation
  errors << 'Email is required'    if params[:email].blank?
  errors << 'Email is invalid'     if params[:email].present? && /\A[\w+\-.]+@[a-z\d\-.]+\.[a-z]+\z/i.match?(params[:email])
  errors << 'Password is required' if params[:password].blank?

  if errors.size == 0
    user = User.find_by(email: params[:email])&.try(:authenticate, params[:password])

    if user.present?
      token = JsonWebToken.encode(user_id: user.id)
    else
      errors << 'Invalid credentials'
    end
  end

  if errors.size == 0
    render json: token
  else
    render json: errors, status: :unauthorized
  end
end

With ServiceRecord 😍

# Inside services/authenticate_user.rb
class AuthenticateUser < ApplicationService
  attribute :email, :string
  attribute :password, :string

  validates :email, :password, presence: true
  validates :email, format: { with: /\A[\w+\-.]+@[a-z\d\-.]+\.[a-z]+\z/i }

  def perform
    user = User.find_by(email: email).try(:authenticate, password)

    if user.present?
      JsonWebToken.encode(user_id: user.id)
    else
      errors.add :authentication, 'invalid credentials'
    end
  end
end


# Inside controllers/users_controller.rb
def sign_in
  response = AuthenticateUser.perform(params.permit(:email, :password))

  if response.success?
    render json: response.result
  else
    render json: response.errors, status: :unauthorized
  end
end

ServiceRecord extends on ActiveModel::Validations, so, everything that you can do there can be done inside a service class and ServiceRecord will make sure that a service only runs the perform function when all validations are passed, otherwise errors will contain details about the validation issues.

Just like validation errors, you can also add custom errors that you want to be reported. Use them to handle errors which are not related to input parameters validation. E.g.

errors.add :authentication, 'invalid credentials'

You can also add callbacks on the perform function similar to ActiveJob's perform function. E.g.

class SampleService < ApplicationService
  before_perform :do_something

  def perform
  end

  private
    
  def do_something
  end
end

Availble callbacks are before_perform, after_perform and around_perform. If a before_perform calls throw :abort, the callback chain is hallted and perform function will not be called.

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request

Bug reports and pull requests are welcome on GitHub at https://github.com/uxxman/service_record.

The gem is available as open source under the terms of the MIT License.