Elixir and Ecto

Transcript

1. elixir atlanta meetup

2. meetup.com/ atlantaelixir @vanstee

3. None

4. • speakers • sponsors • twitter • website • github

   org • [your great idea]

5. elixir and ecto

6. Elixir is a functional, meta-programming aware language built on top

   of the Erlang VM.

7. elixir-lang/elixir @josevalim

8. defmodule Hello do IO.puts "Before world defined" def world do

   IO.puts "Hello World" end IO.puts "After world defined" end Hello.world HELLO.EX
9. None

10. Types

11. # tuple { :a, :b, :c } # list [1,

    2, 3] [a: 1, b: 2, c: 3] # record defrecord User, name: "", age: nil User.new(name: "Patrick", age: 25) TYPE.EX

12. Pattern Matching

13. # assignment a = 1 # => 1 # matching

    1 = a # => 1 2 = a # => ** (MatchError) ... { ^a, b } = { 1, 2 } # b => 2 [head | _] = [1, 2, 3] # head => 1 PATTERN.EX

14. case { 1, 2, 3 } do { 4, 5,

    6 } -> "This won't match" { 1, x, 3 } when x > 0 -> "This will match and assign x" _ -> "No match" end GUARD.EX

15. Processes

16. current_pid = self spawn fn -> current_pid <- :hello end

    receive do :hello -> IO.puts "Hello World" end PROCESS.EX

17. defmodule Stacker.Supervisor do use Supervisor.Behaviour def start_link(stack) do :supervisor.start_link(__MODULE__, stack)

    end def init(stack) do children = [worker(Stacker.Server, [stack])] supervise children, strategy: :one_for_one end end SUPERVISOR.EX

18. Protocols Macros DocTest and lots more

19. elixir-lang.org #elixir-lang

20. None
21. None

22. ecto database query DSL

23. elixir-lang/ecto @ericmj

24. defmodule User do use Ecto.Model queryable "user" do field :name,

    :string end end MODEL.EX

25. defmodule FindUser do import Ecto.Query def find_by_name(name) do query =

    from u in User, where: u.name == ^name, limit: 1 Repo.all(query) end end QUERY.EX
26. None

27. Repo

28. • wrapper • holds connections • executes queries • supervised

    worker

29. defmodule Repo do use Ecto.Repo, adapter: Ecto.Adapters.Postgres def url do

    "ecto://user:pass@localhost/db" end end Repo.all(...) Repo.create(...) Repo.update(...) Repo.delete(...) REPO.EX

30. Entity

31. • fields • associations • elixir record

32. defmodule User do use Ecto.Model queryable "user" do field :name,

    :string field :password, :string, default: "secret" has_many :projects, Project end end MODEL.EX

33. Query

34. • relational algebra • extendable • macros • keyword lists

35. def paginate(query, page, size) do extend query, limit: size, offset:

    (page - 1) * size end query = FindUser.find_by_state("GA") query |> paginate(1, 50) |> Repo.all PAGINATE.EX

36. from u in User, where: u.name == ^name, limit: 1

    QUERY.EX

37. from(u in User) |> where([u], u.name == ^name) |> limit(1)

    |> select([u], u) QUERY.EX

38. select( limit( where( from(u in User), [u], u.name == ^name

    ), 1 ), [u], u ) QUERY.EX

39. Gotchas

40. • error messages • validations • callbacks • type conversions

    • SQL migrations • missing mix tasks

41. elixir-lang/ecto examples/simple

42. Thanks! @josevalim @ericmj #elixir-lang

43. ?