TIL, 2018-02-19, Programming Phoenix

Musings

• Gin, Martini: Go frameworks.
• Plug: Rack for Elixir.
• Hexdocs are the documentation for Phoenix.
• mix archive.install https://github.com/phoenixframework/archives/raw/master/phx_new.ez to install Phoenix or upgrade to latest version. Reference
• Ctrl-C during IEx to break out of it.
• cowboy: Phoenix web server.
• Controller and View are explicitly separate. They are also separated from the template being shown.
• Templates: Embedded Elixir (.eex file).
• Change starting port: dev.exs, HabitsOne.Endpoint, then there is a port section there.
• Or you can do: PORT=4002 mix phx.server
• $ gem cleanup to remove stuff. Solves Unresolved specs during Gem::Specification.reset (which usually means there are old gems in the system which may be interfering with your command). Reference
• Pluralsight Ruby Beyond the Basics:
  • Currying in Ruby.
  • You can do functional things when applying multiple discounts for the report.
  • “What this class does is what this class is.”
  • Functional programming: Composition, referential transparency, and small, specific solutions.

Color Filter

class ColorFilter
  def initialize(color)
    @color = color
  end

  def apply(products)
    products.select { |p| p.color == @color }
  end
end

Programming Phoenix

• mix local.hex to install Hex, the package manager.
• mix phoenix.new -v to check Phoenix version.
• mix phoenix.new hello: Creating the app.
• mix ecto.create: rake db:create?
• mix phx.server: rails server?
• config/dev.exs: Edit this thing for the database.
• iex -S mix phx.server to run the app inside IEx.
• prod.secret.exs.
• MIX_ENV environmental variable to switch between prod/dev.
• This looks really nice:

conn
|> put_flash(:info, "Whoa cool.")
|> put_flash(:error, "Error.")
|> render("world.html", name: 'SWAGG')

• This is like the part of the Rails boot process/Action Pack:

defmodule Hello.Endpoint do
  user Phoenix.Endpint, otp_app: :hello

  plug Plug.Static,
  plug Plug.RequestId,
  plug PLug.Logger

  plug Plug.Parsers,
  plug Plug.MethodOverride,
  plug Plug.Head

  plug Plug.Session,
  plug Hello.Router
end

• This is essentially:

connection
|> Plug.Static.call
|> Plug.RequestId.call
|> router
|> HelloController
...

How I Rented a Nice Place

Reference

• Umbrella: A way of organizing a project into different standalone modules that depend on each other.
• $ mix phx.new --umbrella rent_bot.
• HTML parsing library: Floki.
• HTML requester: HTTPoison.