Learn Phoenix - 1 Code Examples & CST Typing Practice Test

Phoenix is a high-performance, functional web framework written in Elixir, designed for building scalable and maintainable web applications and real-time systems.

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Phoenix Simple Todo App

Learn PHOENIX with Real Code Examples

Updated Nov 27, 2025

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Code Sample Descriptions

Phoenix Simple Todo App

# lib/my_app_web/controllers/todo_controller.ex
defmodule MyAppWeb.TodoController do
  use MyAppWeb, :controller

  alias MyApp.Todos

  def index(conn, _params) do
    todos = Todos.list_todos()
    json(conn, todos)
  end

  def create(conn, %{"todo" => todo_params}) do
    {:ok, todo} = Todos.create_todo(todo_params)
    json(conn, todo)
  end
end

# lib/my_app/todos/todos.ex
defmodule MyApp.Todos do
  alias MyApp.Repo
  alias MyApp.Todos.Todo

  def list_todos do
    Repo.all(Todo)
  end

  def create_todo(attrs) do
    %Todo{}
    |> Todo.changeset(attrs)
    |> Repo.insert()
  end
end

# lib/my_app/todos/todo.ex
defmodule MyApp.Todos.Todo do
  use Ecto.Schema
  import Ecto.Changeset

  schema "todos" do
    field :title, :string
    field :completed, :boolean, default: false
    timestamps()
  end

  def changeset(todo, attrs) do
    todo
    |> cast(attrs, [:title, :completed])
    |> validate_required([:title])
  end
end

Demonstrates a Phoenix controller and view for managing Todo items with a simple JSON API.

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Frequently Asked Questions about Phoenix

What is Phoenix?

Phoenix is a high-performance, functional web framework written in Elixir, designed for building scalable and maintainable web applications and real-time systems.

What are the primary use cases for Phoenix?

Real-time web applications (chat, notifications, dashboards). RESTful APIs and JSON backends. Fault-tolerant, scalable systems. High-concurrency microservices. Rapid development with functional paradigms

What are the strengths of Phoenix?

High concurrency using lightweight processes. Fault-tolerant and highly reliable due to BEAM VM. Real-time communication built-in. Hot code reloading for development speed. Functional, maintainable, and testable codebase

What are the limitations of Phoenix?

Smaller ecosystem compared to Rails or Django. Requires knowledge of Elixir and functional programming. Less mature libraries for some niche needs. Deployment on BEAM may require learning OTP conventions. Not ideal for very simple static sites

How can I practice Phoenix typing speed?

CodeSpeedTest offers 1+ real Phoenix code examples for typing practice. You can measure your WPM, track accuracy, and improve your coding speed with guided exercises.

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Code Sample Descriptions

Phoenix Simple Todo App

# lib/my_app_web/controllers/todo_controller.ex
defmodule MyAppWeb.TodoController do
  use MyAppWeb, :controller

  alias MyApp.Todos

  def index(conn, _params) do
    todos = Todos.list_todos()
    json(conn, todos)
  end

  def create(conn, %{"todo" => todo_params}) do
    {:ok, todo} = Todos.create_todo(todo_params)
    json(conn, todo)
  end
end

# lib/my_app/todos/todos.ex
defmodule MyApp.Todos do
  alias MyApp.Repo
  alias MyApp.Todos.Todo

  def list_todos do
    Repo.all(Todo)
  end

  def create_todo(attrs) do
    %Todo{}
    |> Todo.changeset(attrs)
    |> Repo.insert()
  end
end

# lib/my_app/todos/todo.ex
defmodule MyApp.Todos.Todo do
  use Ecto.Schema
  import Ecto.Changeset

  schema "todos" do
    field :title, :string
    field :completed, :boolean, default: false
    timestamps()
  end

  def changeset(todo, attrs) do
    todo
    |> cast(attrs, [:title, :completed])
    |> validate_required([:title])
  end
end

Demonstrates a Phoenix controller and view for managing Todo items with a simple JSON API.

Let’s Try →

Frequently Asked Questions about Phoenix

What is Phoenix?

Phoenix is a high-performance, functional web framework written in Elixir, designed for building scalable and maintainable web applications and real-time systems.

What are the primary use cases for Phoenix?

What are the strengths of Phoenix?

What are the limitations of Phoenix?

How can I practice Phoenix typing speed?

CodeSpeedTest offers 1+ real Phoenix code examples for typing practice. You can measure your WPM, track accuracy, and improve your coding speed with guided exercises.