Thanks a lot for sharing. A tiny error to be fixed though, I think: you mention everywhere filename: "invoice-#{date}" but the variable date has never been defined.

Thank you so much for sharing such useful tips. One point: you have a tiny typo in Comapny.find_by!(name:...), - it should be Company, I suppose :). Also in the Brake#do_brake method, I don't think the call puts "Brake id: #{self.brake.id}" to correct, - you are calling brake on the instance of the Brake class instead of just calling id method.

AbulAsar S. , no worries, by the way, the code in the repo contains the correct version :).

Error in the template: <i><%= full_name({title.user}) %></i>. It should be task.user instead; Error when calling Project.change_task_state(taskId, target). It should be Organization.change_task_state(taskId, target)

You mentioned: "We are going to place both functions in a separate module organization.ex under trello_app/lib/trello_app folder." I suppose it to be in trello_app/lib folder because: The name of the created module you were displaying later was defmodule TrelloApp.Organization you asked to alias it as TrelloApp.Organization later in the iex session.