Ecto: a database wrapper and language integrated query for Elixir

1. ecto a database wrapper and language integrated query for Elixir
2. defmodule Weather do use Ecto.Model schema "weather" do field :city # Defaults to type :string field :temp_lo, :integer field :temp_hi, :integer field :prcp, :float, default: 0.0 end end query = from w in Weather, where: w.prcp > 0 or is_nil(w.prcp), select: w Repo.all(query)
3. simplicity over convenience
4. “If you want Ecto to get something, you have to explicitly ask for it. This feature will probably seem a little tedious to you…”
5. “…but it is the only way to guarantee your application has predictable performance when the amount of data grows.”
6. defmodule Weather do use Ecto.Model schema "weather" do field :city # Defaults to type :string field :temp_lo, :integer field :temp_hi, :integer field :prcp, :float, default: 0.0 end end query = from w in Weather, where: w.prcp > 0 or is_nil(w.prcp), select: w Repo.all(query)
7. defmodule Weather do use Ecto.Model schema "weather" do field :city # Defaults to type :string field :temp_lo, :integer field :temp_hi, :integer field :prcp, :float, default: 0.0 end end query = from w in Weather, where: w.prcp > 0 or is_nil(w.prcp), select: w Repo.all(query)
8. defmodule Weather do use Ecto.Model schema "weather" do field :city # Defaults to type :string field :temp_lo, :integer field :temp_hi, :integer field :prcp, :float, default: 0.0 end end query = from w in Weather, where: w.prcp > 0 or is_nil(w.prcp), select: w Repo.all(query)
9. defmodule Weather do use Ecto.Model schema "weather" do field :city # Defaults to type :string field :temp_lo, :integer field :temp_hi, :integer field :prcp, :float, default: 0.0 end end query = from w in Weather, where: w.prcp > 0 or is_nil(w.prcp), select: w Repo.all(query)
10. defmodule Weather do use Ecto.Model schema "weather" do field :city # Defaults to type :string field :temp_lo, :integer field :temp_hi, :integer field :prcp, :float, default: 0.0 end end query = from w in Weather, where: w.prcp > 0 or is_nil(w.prcp), select: w Repo.all(query)
11. ‣ data mapper ‣ query language ‣ associations ‣ filtering ‣ validations ‣ lifecycle callbacks ‣ changesets ‣ migrations ‣ custom types ‣ embedded structs
12. compose queries
13. # Create a query query = from w in Weather, where: w.prcp > 0 # Extend the query query = from w in query, select: w.city
14. repository
15. Repo.get_by(Post, title: "My post") Repo.transaction(fn -> Repo.update!(%{alice | balance: alice.balance - 10}) Repo.update!(%{bob | balance: bob.balance + 10}) end) post = Repo.get!(Post, 42) post = %{post | title: "New title"} case Repo.update post do {:ok, model} -> # Updated with success {:error, changeset} -> # Something went wrong end
16. Repo.get_by(Post, title: "My post") Repo.transaction(fn -> Repo.update!(%{alice | balance: alice.balance - 10}) Repo.update!(%{bob | balance: bob.balance + 10}) end) post = Repo.get!(Post, 42) post = %{post | title: "New title"} case Repo.update post do {:ok, model} -> # Updated with success {:error, changeset} -> # Something went wrong end
17. Repo.get_by(Post, title: "My post") Repo.transaction(fn -> Repo.update!(%{alice | balance: alice.balance - 10}) Repo.update!(%{bob | balance: bob.balance + 10}) end) post = Repo.get!(Post, 42) post = %{post | title: "New title"} case Repo.update post do {:ok, model} -> # Updated with success {:error, changeset} -> # Something went wrong end
18. changesets
19. defmodule User do use Ecto.Model import Ecto.Changeset schema "users" do field :name field :email field :age, :integer end def changeset(user, params \\ :empty) do user |> cast(params, ~w(name email), ~w(age)) |> validate_format(:email, ~r/@/) |> unique_constraint(:email) |> validate_inclusion(:age, 18..100) end end
20. defmodule User do use Ecto.Model import Ecto.Changeset schema "users" do field :name field :email field :age, :integer end def changeset(user, params \\ :empty) do user |> cast(params, ~w(name email), ~w(age)) |> validate_format(:email, ~r/@/) |> unique_constraint(:email) |> validate_inclusion(:age, 18..100) end end
21. defmodule User do use Ecto.Model import Ecto.Changeset schema "users" do field :name field :email field :age, :integer end def changeset(user, params \\ :empty) do user |> cast(params, ~w(name email), ~w(age)) |> validate_format(:email, ~r/@/) |> unique_constraint(:email) |> validate_inclusion(:age, 18..100) end end
22. defmodule User do use Ecto.Model import Ecto.Changeset schema "users" do field :name field :email field :age, :integer end def changeset(user, params \\ :empty) do user |> cast(params, ~w(name email), ~w(age)) |> validate_format(:email, ~r/@/) |> unique_constraint(:email) |> validate_inclusion(:age, 18..100) end end
23. defmodule User do use Ecto.Model import Ecto.Changeset schema "users" do field :name field :email field :age, :integer end def changeset(user, params \\ :empty) do user |> cast(params, ~w(name email), ~w(age)) |> validate_format(:email, ~r/@/) |> unique_constraint(:email) |> validate_inclusion(:age, 18..100) end end
24. defmodule User do use Ecto.Model import Ecto.Changeset schema "users" do field :name field :email field :age, :integer end def changeset(user, params \\ :empty) do user |> cast(params, ~w(name email), ~w(age)) |> validate_format(:email, ~r/@/) |> unique_constraint(:email) |> validate_inclusion(:age, 18..100) end end
25. def registration_changeset(model, params) do model |> changeset(params) |> cast(params, ~w(password), []) |> validate_length(:password, min: 6, max: 100) |> put_pass_hash() end
26. associations
27. query = from p in Post, preload: [:comments] query = from p in Post, join: c in assoc(p, :comments), where: c.published_at > p.updated_at, preload: [comments: c] query |> Repo.all
28. familiar different pragmatic fun