Elixir and Ecto

Transcript

1. elixir atlanta meetup
2. meetup.com/ atlantaelixir @vanstee
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
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
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
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. ?