flakes

Description

Flakes is an extension of Active Model and Active Job to provide service object functionality.

This started as an experiment to write a framework for hexagonal architecture but turned into a collection of service object functions that I am reusing for several projects.

The idea is to break down the business logic into basic operations that can be composed to provide complex functionality but can be easily unit tested.

Getting started

To install:

gem install flakes

If you use a Gemfile:

  gem "flakes"

Features

• Flake takes failure and success procs
• #with_valid_params
  • runs validations and causes flake to fail if invalid
  • wraps code into ActiveRecord transaction
• Flake fails if an object with errors is passed to #success
• Calling execute_later runs Flake in background
• Active Model validations

Example

Simple example for creating posts and adding tags to them during creation and afterwards.

  class PostsController < ApplicationController
    def create
      flake = PostCreating.new(post_params)
      flake.on_success { |post| @post = PostPresenter.new(post) }
      flake.on_failure { |errors| json_error(errors) }
      flake.execute
    end

    def add_tags
      flake = PostTagAdding.new(tag_params)
      flake.on_success { |post| @post = PostPresenter.new(post) }
      flake.on_failure { |errors| json_error(errors) }
      flake.execute
    end

    private

    post_params
      params.require(:post).permit(:text, :tags).merge(user: current_user)
    end

    tag_params
      params.permit(:tags).megre(post_id: params[:id])
    end
  end

  class PostCreating < Flake
    attr_accessor :text, :tags, :user

    validates :text, :tags, :user, presence: true

    def execute
      with_valid_params do
        create_post
        add_tags

        success(post)
      end
    end

    private

    attr_reader :post

    def create_post
      @post = Post.create!(user: user, text: text)
    end

    def add_tags
      @post = PostTagAdding.execute(post: post, tags: tags)
    end
  end

  class PostTagAdding < Flake
    attr_accessor :post_id, :post, :tags

    validates :post, :tags, presence: true

    def execute
      with_valid_params do
        add_tags

        success(post)
      end
    end

    private

    def add_tags
      post.tags << tag_objects
    end

    def tag_objects
      tag_names.map do { |name| Tag.find_or_create_by(name: name) }
    end

    def tag_names
      tags.split(",")
    end

    def post
      @post ||= Post.find_by(id: post_id)
    end
  end

Contribute

If you are using flakes and missing something, feel free to open a PR. Currently the functionality is only tested through my projects, but I will add tests and better documentation in the near future.