Phoenix

# lib/my_app_web/controllers/user_controller.ex
defmodule MyAppWeb.UserController do
  use MyAppWeb, :controller

  alias MyApp.Accounts
  alias MyApp.Accounts.User

  # GET /api/users
  def index(conn, _params) do
    users = Accounts.list_users()
    render(conn, :index, users: users)
  end

  # GET /api/users/:id
  def show(conn, %{"id" => id}) do
    user = Accounts.get_user!(id)
    render(conn, :show, user: user)
  end

  # POST /api/users
  def create(conn, %{"user" => user_params}) do
    case Accounts.create_user(user_params) do
      {:ok, %User{} = user} ->
        conn
        |> put_status(:created)
        |> put_resp_header("location", ~p"/api/users/#{user}")
        |> render(:show, user: user)

      {:error, %Ecto.Changeset{} = changeset} ->
        conn
        |> put_status(:unprocessable_entity)
        |> render(:error, changeset: changeset)
    end
  end
end

# lib/my_app_web/live/counter_live.ex
defmodule MyAppWeb.CounterLive do
  use MyAppWeb, :live_view

  # 초기 상태 설정
  def mount(_params, _session, socket) do
    {:ok, assign(socket, count: 0)}
  end

  # 실시간 UI 렌더링 (HEEx 템플릿)
  def render(assigns) do
    ~H"""
    <div class="counter-container">
      <h1>실시간 카운터</h1>
      <p class="count"><%= @count %></p>

      <div class="buttons">
        <button phx-click="decrement">-</button>
        <button phx-click="increment">+</button>
        <button phx-click="reset">Reset</button>
      </div>
    </div>
    """
  end

  # 이벤트 핸들러 - 서버에서 처리, 자동으로 UI 업데이트
  def handle_event("increment", _params, socket) do
    {:noreply, update(socket, :count, &(&1 + 1))}
  end

  def handle_event("decrement", _params, socket) do
    {:noreply, update(socket, :count, &(&1 - 1))}
  end

  def handle_event("reset", _params, socket) do
    {:noreply, assign(socket, count: 0)}
  end
end

# router.ex에 추가
# live "/counter", CounterLive

# lib/my_app_web/live/chat_live.ex
defmodule MyAppWeb.ChatLive do
  use MyAppWeb, :live_view

  def mount(%{"room" => room}, _session, socket) do
    # 채팅방 토픽 구독
    if connected?(socket) do
      Phoenix.PubSub.subscribe(MyApp.PubSub, "chat:#{room}")
    end

    {:ok, assign(socket, room: room, messages: [], message: "")}
  end

  # 메시지 전송 - 모든 구독자에게 브로드캐스트
  def handle_event("send", %{"message" => msg}, socket) do
    Phoenix.PubSub.broadcast(
      MyApp.PubSub,
      "chat:#{socket.assigns.room}",
      {:new_message, %{text: msg, time: DateTime.utc_now()}}
    )
    {:noreply, assign(socket, message: "")}
  end

  # 브로드캐스트 메시지 수신
  def handle_info({:new_message, message}, socket) do
    messages = socket.assigns.messages ++ [message]
    {:noreply, assign(socket, messages: messages)}
  end
end