This document provides an introduction to Elixir and the Phoenix web framework. It begins with background on Elixir and why it was created. It then demonstrates basic Elixir concepts like data types, operators, functions and modules. It shows how to create a Phoenix project, configure it, define models, repositories, controllers, views, routers and tests. The document aims to provide readers with an overview of building web applications with Elixir and Phoenix.

1. Introduction to Elixir and
Phoenix
Created by Ridwan Fadjar Septian,
At SenseHealth B.V.
Bandung, 26th September 2018

2. Disclaimer
- I am just curious about Elixir and Phoenix Web Framework for personal usage only
- Currently I don’t have an experience using Elixir in production
- I bought Elixir and Phoenix course on Udemy for my hobby
- Alam embrace me to learn Elixir and set up a sharing session

3. Background and Motivation
Why Elixir?

4. Elixir at Glance
Fundamental

5. Hello world
iex > IO.puts("hello world!")
hello world!
:ok

6. Data Type
iex> 255
255
iex> 0b0110
6
iex> 0o644
420
iex> 0x1F
31
iex> 3.14
3.14
iex> 1.0e-10
1.0e-10
iex> true
true
iex> false
False

7. Data Type
iex> :foo
:foo
iex> :foo == :bar
false
iex> "Hello"
"Hello"
iex> "さようなら"
"さようなら"
iex> "foo
...> bar"
"foonbar"
iex> "foonbar"
"foonbar"

8. Basic Operator
iex> 2 + 2
4
iex> 2 - 1
1
iex> 2 * 5
10
iex> 10 / 5
2.0
iex> div(10, 5)
2
iex> rem(10, 3)
1

9. Basic Operator
iex> -20 || true
-20
iex> false || 42
42
iex> 42 && true
true
iex> 42 && nil
nil
iex> !42
false
iex> !false
true

10. Basic Operator
iex> true and 42
42
iex> false or true
true
iex> not false
true
iex> 1 > 2
false
iex> 1 != 2
true
iex> 2 == 2
true
iex> 2 <= 3
true
iex> 2 == 2.0
true
iex> 2 === 2.0
false

11. Basic Operator
iex> "Elixir rocks" |> String.upcase() |> String.split()
["ELIXIR", "ROCKS"]

12. Conditional
iex> if String.valid?("Hello") do
...> "Valid string!"
...> else
...> "Invalid string."
...> end
"Valid string!"
iex> if "a string value" do
...> "Truthy"
...> end
"Truthy"

13. Conditional
iex> unless is_integer("hello") do
...> "Not an Int"
...> end
"Not an Int"

14. Conditional
iex> case {:ok, "Hello World"} do
...> {:ok, result} -> result
...> {:error} -> "Uh oh!"
...> _ -> "Catch all"
...> end
"Hello World"

15. Conditional
iex> cond do
...> 2 + 2 == 5 ->
...> "This will not be true"
...> 2 * 2 == 3 ->
...> "Nor this"
...> 1 + 1 == 2 ->
...> "But this will"
...> end
"But this will"

16. Recursion
defmodule Loop do
def print_multiple_times
(msg, n) when n <= 1 do
IO.puts msg
end
def print_multiple_times
(msg, n) do
IO.puts msg
print_multiple_times
(msg, n - 1)
end
end
Loop.print_multiple_times
("Hello", 10)

17. Function
iex> sum = fn (a, b) -> a + b end
iex> sum.(2, 3)
5
iex> sum = &(&1 + &2)
iex> sum.(2, 3)
5

18. Function and Module
defmodule Greeter do
def hello(name) do
"Hello, " <> name
end
end
iex> Greeter.hello("Sean")
"Hello, Sean"

19. Function and Module
defmodule Greeter2 do
def hello(), do: "Hello, anonymous person!" # hello/0
def hello(name), do: "Hello, " <> name # hello/1
def hello(name1, name2), do: "Hello, #{name1} and #{name2}"
# hello/2
end
iex> Greeter2.hello()
"Hello, anonymous person!"
iex> Greeter2.hello("Fred")
"Hello, Fred"
iex> Greeter2.hello("Fred", "Jane")
"Hello, Fred and Jane"

20. Mix
Package Manager in Elixir

21. Phoenix
Web Framework for Elixir

22. Getting Started
$ mix archive.install
https://github.com/phoenixframework/archives/raw/master/phx_new.ez
$ mix phx.new tracking-api --app my_app --module TrackingAPI --no-brunch --no-html
$ cd tracking-api
$ mix phx.server

23. Supported Database
- PostgreSQL
- MySQL

24. Configs
use Mix.Config
config :tracking_api, TrackingAPIWeb.Endpoint,
http: [port: 4000],
debug_errors: false,
code_reloader: true,
check_origin: false,
watchers: []
config :logger, :console, format: "[$level] $messagen"
config :phoenix, :stacktrace_depth, 20
config :tracking_api, TrackingAPI.Repo,
adapter: Ecto.Adapters.Postgres,
username: "phoenix",
password: "phoenix",
database: "tracking_api_dev",
hostname: "localhost",
pool_size: 10

25. Models
schema "gps_tracking" do
field :application_id, Ecto.UUID
field :created_at, :utc_datetime
field :latitude, :string
field :longitude, :string
field :user_id, Ecto.UUID
timestamps()
end
@doc false
def changeset(gps_tracking, attrs) do
gps_tracking
|> cast(attrs, [:application_id, :user_id, :latitude, :longitude, :created_at])
|> validate_required([:application_id, :user_id, :latitude, :longitude, :created_at])
end

26. Repo
def list_gps_tracking do
Repo.all(GPSTracking)
end
def get_gps_tracking!(id), do: Repo.get!(GPSTracking, id)
def create_gps_tracking(attrs %{}) do
%GPSTracking{}
|> GPSTracking.changeset(attrs)
|> Repo.insert()
end
def update_gps_tracking(%GPSTracking{} = gps_tracking, attrs) do
gps_tracking
|> GPSTracking.changeset(attrs)
|> Repo.update()
end
def delete_gps_tracking(%GPSTracking{} = gps_tracking) do
Repo.delete(gps_tracking)
end
def change_gps_tracking(%GPSTracking{} = gps_tracking) do
GPSTracking.changeset(gps_tracking, %{})
end

27. Controllers
defmodule TrackingAPIWeb.GPSTrackingController do
use TrackingAPIWeb, :controller
alias TrackingAPI.Tracking
alias TrackingAPI.Tracking.GPSTracking
action_fallback TrackingAPIWeb.FallbackController
def index(conn, _params) do
gps_tracking = Tracking.list_gps_tracking()
render(conn, "index.json", gps_tracking: gps_tracking)
end
def create(conn, %{"gps_tracking" => gps_tracking_params}) do
with {:ok, %GPSTracking{} = gps_tracking} <- Tracking.create_gps_tracking(gps_tracking_params) do
conn
|> put_status(:created)
|> put_resp_header("location", gps_tracking_path(conn, :show, gps_tracking))
|> render("show.json", gps_tracking: gps_tracking)
end
end
end

28. We cannot use update endpoint! We exclude it.

29. Views
def render("index.json", %{gps_tracking: gps_tracking}) do
%{data: render_many(gps_tracking, GPSTrackingView, "gps_tracking.json")}
end
def render("show.json", %{gps_tracking: gps_tracking}) do
%{data: render_one(gps_tracking, GPSTrackingView, "gps_tracking.json")}
end
def render("gps_tracking.json", %{gps_tracking: gps_tracking}) do
%{id: gps_tracking.id,
application_id: gps_tracking.application_id,
user_id: gps_tracking.user_id,
latitude: gps_tracking.latitude,
longitude: gps_tracking.longitude,
created_at: gps_tracking.created_at}
end

30. Router
defmodule TrackingAPIWeb.Router do
use TrackingAPIWeb, :router
pipeline :api do
plug :accepts, ["json"]
end
scope "/api", TrackingAPIWeb do
pipe_through :api
resources "/gps_tracking", GPSTrackingController, except: [:edit]
end
end

31. Testing
test "list_gps_tracking/0 returns all gps_tracking" do
gps_tracking = gps_tracking_fixture()
assert Tracking.list_gps_tracking() == [gps_tracking]
end
test "get_gps_tracking!/1 returns the gps_tracking with given id" do
gps_tracking = gps_tracking_fixture()
assert Tracking.get_gps_tracking!(gps_tracking.id) == gps_tracking
end
test "create_gps_tracking/1 with valid data creates a gps_tracking" do
assert {:ok, %GPSTracking{} = gps_tracking} = Tracking.create_gps_tracking(@valid_attrs)
assert gps_tracking.application_id == "7488a646-e31f-11e4-aace-600308960662"
assert gps_tracking.created_at == DateTime.from_naive!(~N[2010-04-17 14:00:00.000000Z], "Etc/UTC")
assert gps_tracking.latitude == "some latitude"
assert gps_tracking.longitude == "some longitude"
assert gps_tracking.user_id == "7488a646-e31f-11e4-aace-600308960662"
end
test "create_gps_tracking/1 with invalid data returns error changeset" do
assert {:error, %Ecto.Changeset{}} = Tracking.create_gps_tracking(@invalid_attrs)
end

32. References
- https://hexdocs.pm/phoenix/
- https://elixirschool.com/
- https://www.tutorialspoint.com/elixir/
- https://elixir-lang.org/docs.html
- https://github.com/h4cc/awesome-elixir
- https://github.com/droptheplot/awesome-phoenix

33. Demo