The Application: Getting Started

The application

The application just starts a standard supervisor without children. This is how it’s done.

defmodule Bookstore.App do
  use Application

  def start(_type, _args) do
    Bookstore.Sup.start_link()
  end

  def stop(_state) do
    :ok
  end
end

And now for the supervisor. Let’s look at how that works.

The supervisor

This is what our supervisor would look like.

defmodule Bookstore.Sup do
  use Supervisor

  def start_link() do
    Supervisor.start_link(__MODULE__, [], name: __MODULE__)
  end

  def init([]) do
    Bookstore.DB.load_queries()
    Supervisor.init([], strategy: :one_for_one)
  end
end

Note that Bookstore.DB.load_queries() gets called. This function is not yet defined. Its role, though, will be to find all the SQL queries within a file we’ll define in priv/queries.sql, which are labeled by name in the comments.

Queries