ecto a database wrapper and language integrated query for Elixir 

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) 

simplicity over convenience 

“If you want Ecto to get something, you have to explicitly ask for it. This feature will probably seem a little tedious to you…” 

“…but it is the only way to guarantee your application has predictable performance when the amount of data grows.” 

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) 

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) 

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) 

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) 

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) 

‣ data mapper ‣ query language ‣ associations ‣ filtering ‣ validations ‣ lifecycle callbacks ‣ changesets ‣ migrations ‣ custom types ‣ embedded structs 

compose queries 

# Create a query query = from w in Weather, where: w.prcp > 0 # Extend the query query = from w in query, select: w.city 

repository 

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 

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 

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 

changesets 

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 

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 

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 

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 

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 

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 

def registration_changeset(model, params) do model |> changeset(params) |> cast(params, ~w(password), []) |> validate_length(:password, min: 6, max: 100) |> put_pass_hash() end 

associations 

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 

familiar different pragmatic fun