laserlemon

class UpdateUser
  include Interactor
  
  # Receives: user - A User record to update.
  #           new_attributes - A hash of attributes to be saved to the user.
  # Updates: user
  # Provides: old_attributes - A hash of only those user attributes that
  #             changed and their original values.
  
  def call

laserlemon

Introduction

Disclaimer: I'm a one-day-old Elixir/Phoenix developer.

In Sonny's training yesterday, we used an Ecto.Changeset to handle user registration (a database-backed operation). This worked perfectly for rendering the intial form and re-rendering the form with validation errors.

This is because our Workshop.RegistrationController is calling Repo.Insert which sets the changeset's :action, whether or not the insertion succeeds. Then Phoenix.HTML's form_for function appropriately sets errors on the form so they can be rendered on the page.

The Problem

laserlemon

require "ransack/visitor"
require "ransack/adapters/active_record/context"

module Ransack
  Visitor.class_eval do
    def visit_Ransack_Nodes_Sort(object)
      # The first half of this conditional is the original implementation in
      # Ransack, as of version 1.6.6.
      #
      # The second half of the conditional kicks in when the column name

laserlemon

begin
  require "active_record" # 4.2.4
  require "ransack" # 1.6.6
  require "sqlite3" # 1.3.11
rescue LoadError
  warn "⚠️  Install the activerecord, ransack, and sqlite3 gems first."
  exit
end

ActiveRecord::Base.establish_connection(

laserlemon

Keeping Track of Technical Debt

Don't forget your debt! Developers have a tendency to forget the bad or ugly code they write. In the Real World™, there are times when sacrifices in code quality need to be made in the interest of time. We call it "cowboy coding" and it's a slippery slope that can lead to loads of technical debt.

A big problem is that it's too easy for technical debt to be out of sight and out of mind. There are a few good ways to increase your debt's visibility.

Code Comments

Your first step should be to add code comments where appropriate to document technical debt as it arises. Fight the urge to deny the fact that you're writing less-than-awesome code. Try to include what's wrong with the code in question as well as at least one potential solution.

laserlemon

class PlaceOrder
  include Interactor
  
  # What goes here?
  
  before do
    context.user ||= User.find(context.user_id)
  end
  
  def call

laserlemon

class FinishOptimization
  include Interactor::Organizer
  
  organize CommitImages
  organize PushImages,
           CreateOrUpdatePullRequest,
           MarkAsFinished, if: -> { context.optimized_commit_sha }
end

laserlemon

Keybase proof

I hereby claim:

• I am laserlemon on github.
• I am laserlemon (https://keybase.io/laserlemon) on keybase.
• I have a public key whose fingerprint is CDB6 894C 1DA5 35AB 8425 DD90 C650 CD1B 7189 C7DF

To claim this, I am signing this object:

laserlemon

# my_gem/cli.rb

require "thor"

require "my_gem/cli/foo_bar"
require "my_gem/cli/foo_baz"
require "my_gem/cli/install"

module MyGem
  class CLI < Thor

laserlemon

What is an Interactor?

An interactor is a simple, single-purpose object.

Interactors are used to encapsulate your application's business logic. Each interactor represents one thing that your application does.

Context

An interactor is given a context. The context contains everything the interactor needs to do its work.