Ecto: the easy and the hard

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1. Никита Соболев github.com/sobolevn
2. Ecto - ORM
4. Ecto - RM
5. Ecto - M?
6. DSL для коммуникации с базами данных оболочка, которая предоставляет возможность коммуникации с базой данных The No- Compromise Database Wrapper predominant library for working with databases popular database wrapper and integrated query language
7. Ecto состоит из 4 наиболее важных частей • Repo • Schema • Changeset • Query
8. defp deps do [ {:ecto, "~> 2.2.8"}, ] end
9. Generators • mix ecto.gen.repo • mix ecto.gen.migration create_invoices • mix phx.gen.schema # phoenix only!
10. Repo defmodule EctoIsEasy.Repo do use Ecto.Repo, otp_app: :ecto_is_easy end
11. use Mix.Config config :ecto_is_easy, EctoIsEasy.Repo, adapter: Ecto.Adapters.Postgres, database: "ecto_is_easy_repo", username: "user", password: "pass", hostname: "localhost" config :ecto_is_easy, ecto_repos: [EctoIsEasy.Repo]
12. Adapters • Postges, MySQL, MSSQL, SQLite • Mnesia, MongoDB, Cassandra, Riak • Github, json
13. Schema
14. defmodule EctoIsEasy.Repo.Migrations.CreateArticls do use Ecto.Migration def change do create table(:articles) do add :link, :uuid add :body, :text add :visits, :integer timestamps end create index(:articles, [:link]) end end
15. defmodule EctoIsEasy.Article do use Ecto.Schema import Ecto.Changeset schema "articles" do field :link, Ecto.UUID field :body, :string field :visits, :integer, default: 0 timestamps() end @fields ~w(link body visits) def changeset(data, params \\ %{}) do data |> cast(params, @fields) |> validate_required([:link, :body]) |> validate_length(:body, min: 100) end end
16. А где changeset?
17. iex(2)> article = EctoIsEasy.Article.changeset(%Article{}, %{ link: Ecto.UUID.generate(), body: "Some long body", }) #Ecto.Changeset< action: nil, changes: %{ body: "Some long body", link: "c44a6196-7c33-4483-b1aa-53820d58bf2d" }, errors: [], data: #EctoIsEasy.Article<>, valid?: true >
18. iex(4)> EctoIsEasy.Repo.insert article {:ok, %EctoIsEasy.Article{ __meta__: #Ecto.Schema.Metadata<:loaded, "articles">, body: "Some long body", id: 1, inserted_at: ~N[2018-03-02 14:20:38.776091], link: "c44a6196-7c33-4483- b1aa-53820d58bf2d", updated_at: ~N[2018-03-02 14:20:38.778340], visits: 0 }}
19. Queries With subqueries, transactions, DSLs
20. iex(1)> import Ecto.Query iex(2)> query = from(a in Article, where: a.visits == 0) iex(3)> Repo.all query [ %EctoIsEasy.Article{ __meta__: #Ecto.Schema.Metadata<"articles">, body: "Some long body", id: 1, inserted_at: ~N[2018-03-02 14:20:38.776091], link: "c44a6196-7c33-4483-b1aa-53820d58bf2d", updated_at: ~N[2018-03-02 14:20:38.778340], visits: 0 } ]
21. Или альтернативный синтаксис Article |> where([a], a.visits == 0) |> select([:id, :link]) |> Repo.all
22. Приятные мелочи
23. Ecto.Multi defmodule EctoIsEasy.BanHammer do alias Ecto.Multi def ban(article) do Multi.new |> Multi.update(:article, ...) |> Multi.insert(:log, ...) |> Multi.update(:author, ...) end end iex(1)> Repo.transaction(BanHammer.ban(article))
24. Custom fields ecto_autoslug_field
25. defmodule EctoAutoslugField.Type do @moduledoc """ This module represents a simple wrapper around ':string'. """ @behaviour Ecto.Type def type, do: :string def cast(string) when is_binary(string), do: {:ok, string} def cast(_), do: :error def load(string) when is_binary(string), do: {:ok, string} def load(_), do: :error def dump(string) when is_binary(string), do: {:ok, string} def dump(_), do: :error end
26. Embed schema Потому что можно запихать много данных в одну схему
27. defmodule Person do use Ecto.Model schema "people" do field :name embeds_many :addresses, Address end end defmodule Address do use Ecto.Model embedded_schema do field :street_name field :city field :state field :zip_code end end
28. Integrations :phoenix_ecto
29. Полезные материалы • Учебник на русском: https:// elixirschool.com/ru/lessons/specifics/ecto • Книга "What's new in Ecto 2.0" на русском: https://github.com/wunsh/ecto-book-ru • ecto_autoslug_field: https://github.com/ sobolevn/ecto_autoslug_field • Ecto.Multi: https://medium.com/heresy-dev/ a-brief-guide-to-ecto-multi-9c8ea0c729f0
30. http://elixir-lang.moscow
31. Вопросы? github.com/sobolevn