LiveViewで認証付きのチャットアプリを構築する(認証機能作成)

# /lib/lv_chat/accounts.ex
def get_user_by(params) do
    Repo.get_by(User, params)
end

def get_user_by_name(name) do
    get_user_by(name: name)
end

def authenticate_by_name_and_pass(name, given_pass) do  user = get_user_by_name(name)

  cond do
  user && Pbkdf2.verify_pass(given_pass, user.password_hash) ->
    {:ok, user}
  user ->
    {:error, :unauthorized}
  true ->
    Pbkdf2.no_user_verify()
    {:error, :not_found}
  end
end

# /lib/lv_chat_web/controllers/session_controller.ex
defmodule LvChatWeb.SessionController do
  use LvChatWeb, :controller

  def new(conn, _) do
    render(conn, "new.html")
  end

  def create(conn, %{"session" => %{"name" => name, "password" => pass}}) do
    case LvChat.Accounts.authenticate_by_name_and_pass(name, pass) do      {:ok, user} ->
        conn
        |> LvChatWeb.Auth.login(user)
        |> put_flash(:info, "Welcome back!")
        |> redirect(to: Routes.page_path(conn, :index))
      {:error, _reason} ->
        conn
        |> put_flash(:error, "無効なユーザー名とパスワードの組み合わせです。")
        |> render("new.html")
    end
  end

  def delete(conn, _) do
    conn
    |> LvChatWeb.Auth.logout()
    |> redirect(to: Routes.page_path(conn, :index))
  end
end

# /lib/lv_chat_web/controllers/auth.ex
defmodule LvChatWeb.Auth do
  import Plug.Conn  import Phoenix.Controller

  alias LvChatWeb.Router.Helpers, as: Routes

  def init(opts), do: opts
  def call(conn, _opts) do    user_id = get_session(conn, :user_id)
    cond do
      user = conn.assigns[:current_user] ->
        put_current_user(conn, user)
      user = user_id && LvChat.Accounts.get_user!(user_id) ->
        put_current_user(conn, user)
      true ->
        assign(conn, :current_user, nil)
    end
  end
  ...
end

# /lib/lv_chat_web/router.ex
pipeline :browser do
  plug :accepts, ["html"]
  plug :fetch_session
  plug :fetch_flash
  plug :protect_from_forgery
  plug :put_secure_browser_headers
  plug LvChatWeb.Authend

# /lib/lv_chat_web.ex
def controller do
  quote do
    use Phoenix.Controller, namespace: LvChatWeb

    import Plug.Conn
    import LvChatWeb.Gettext
    import LvChatWeb.Auth, only: [authenticate_user: 2]    alias LvChatWeb.Router.Helpers, as: Routes
  end
end

# lib/lv_chat_web.ex
def router do
  quote do
    use Phoenix.Router
    import Plug.Conn
    import Phoenix.Controller
    import LvChatWeb.Auth, only: [authenticate_user: 2]  end
end

# /lib/lv_chat_web/templates/layout/app.html.eex
<nav role="navigation">
  <ul>
    <%= if @current_user do %>      <li><%= @current_user.name %></li>      <li>        <%= link "Log out",              to: Routes.session_path(@conn, :delete, @current_user),              method: "delete" %>      </li>    <% else %>      <li><%= link "Register", to: Routes.user_path(@conn, :new) %></li>      <li><%= link "Log in", to: Routes.session_path(@conn, :new) %></li>    <% end %>  </ul>
</nav>

# /lib/lv_chat_web/router.ex
scope "/", LvChatWeb do
  pipe_through :browser

  resources "/users", UserController, only: [:new, :create]
  resources "/sessions", SessionController, only: [:new, :create]
end

scope "/", LvChatWeb do
  pipe_through [:browser, :authenticate_user]
  get "/", PageController, :index
  resources "/sessions", SessionController, only: [:delete]
end