无法理解 JWT 身份验证中的解构 (Phoenix)

Question

我正在设置一个模式，我在 Phoenix 的几个地方看到过这种模式，用于 API 身份验证，使用 Comeonin 和 Guardian 进行 JWT 身份验证。

当我从 CURL POST 到 MyApp.SessionsController.create/2 时，我得到了 MyApp.Session.authenticate/1 的 user 响应，正如我所期望的那样。但是，我应该将其解构为 {:ok, jwt, _full_claims}，然后可以将其通过管道传输到 Guardian。我使用 IO.inspect user 查看 user 对象并得到以下错误：

航站楼：

curl -H "Content-Type: application/json" -X POST -d '{"email":"me@myapp.com","password":"password", "session":{"email":"mark@myapp.com", "password":"password"}}' http://localhost:4000/api/v1/sessions

当我在 IEX 中 IO.inspect user 时，我看到了这个：

%MyApp.User{__meta__: #Ecto.Schema.Metadata<:loaded, "users">, avatar_url: nil,
 email: "me@myapp.com", handle: "me", id: 2,
 inserted_at: ~N[2017-08-22 18:26:10.000033], password: nil,
 password_hash: "b$LpJTWWEEUzrkkzu2w9sRheGHkh0YOgUIOkLluk05StlmTP6EiyPA6",
 updated_at: ~N[2017-08-22 18:26:10.007796]}

我看到这个错误：

Request: POST /api/v1/sessions
** (exit) an exception was raised:
    ** (MatchError) no match of right hand side value: %MyApp.User{__meta__: #Ecto.Schema.Metadata<:loaded, "users">, avatar_url: nil, email: "me@myapp.com", handle: "mark", id: 2, inserted_at: ~N[2017-08-22 18:26:10.000033], password: nil, password_hash: "b$LpJTWWEEUzrkkzu2w9sRheGHkh0YOgUIOkLluk05StlmTP6EiyPA6", updated_at: ~N[2017-08-22 18:26:10.007796]}
        (myapp) web/controllers/api/v1/sessions_controller.ex:11: MyApp.SessionsController.create/2

这到底是什么意思：`{:ok, jwt, _full_claims} = user`？

设置如下：

# mix.exs
  defp deps do
    [
      {:distillery, "~> 1.4", runtime: false},
      {:phoenix, "~> 1.3.0-rc", override: true},
      {:phoenix_ecto, "~> 3.2"},
      ...
      {:comeonin, "~> 4.0"},
      {:bcrypt_elixir, "~> 0.12.0"},
      {:guardian, "~> 0.14.5"},
]

# web/router.ex
  ...
  pipeline :api do
    plug :accepts, ["json"]
    plug Guardian.Plug.VerifyHeader
  end

  scope "/api", MyApp do
    pipe_through :api

    scope "/v1" do
      post "/sessions", SessionsController, :create
    end
  end
...

# web/controllers/session_controller.ex
defmodule MyApp.SessionsController do  
  use MyApp.Web, :controller

  alias MyApp.{Repo, User}

  plug :scrub_params, "session" when action in [:create]

  def create(conn, %{"session" => session_params}) do
    case MyApp.Session.authenticate(session_params) do
    {:ok, user} ->
      {:ok, jwt, _full_claims} = user
        IO.inspect user       # Trying to test it here 
        |> Guardian.encode_and_sign(:token)
      conn
        |> put_status(:created)
        |> render("show.json", jwt: jwt, user: user)
    :error ->
      conn
      |> put_status(:unprocessable_entity)
      |> render("error.json")
    end
  end

# web/services/session.ex
defmodule MyApp.Session do 

  alias MyApp.{Repo, User}
  import Bcrypt

  def authenticate(%{"email" => email, "password" => password}) do
    case Repo.get_by(User, email: email) do
      nil -> 
        :error
      user ->
        case verify_password(password, user.password_hash) do
          true ->
            {:ok, user}
          _ ->
            :error
        end
    end
  end

  defp verify_password(password, pw_hash) do
    Comeonin.Bcrypt.checkpw(password, pw_hash)
  end
end

# lib/MyApp/User.ex
defmodule MyApp.User do
  use MyApp.Web, :model

  schema "users" do
    field :email, :string
    field :handle, :string
    field :password_hash, :string
    field :avatar_url, :string
    field :password, :string, virtual: true

    timestamps
  end

  def changeset(model, params \ :empty) do
    model
    |> cast(params, [:email, :handle, :password_hash, :password, :avatar_url])
    |> validate_required([:email])
    |> validate_length(:email, min: 1, max: 255)
    |> validate_format(:email, ~r/@/)
  end

编辑：添加监护人信息

#config/config.exs
config :guardian, Guardian,
  issuer: "MyApp",
  ttl: { 30, :days},
  verify_issuer: true,
  secret_key: "abc123",
  serializer: MyApp.GuardianSerializer

#lib/MyApp/guardian_serializer.ex
defmodule MyApp.GuardianSerializer do
  @behaviour Guardian.Serializer
  alias MyApp.Repo
  alias MyApp.User

  def for_token(user = %User{}), do: {:ok, "User:#{user.id}"}
  def for_token(_), do: {:error, "Unknown resource type"}

  def from_token("User:" <> id), do: {:ok, Repo.get(User, id)}
  def from_token(_), do: {:error, "Unknown resource type"}
end

Answer 1

{:ok, jwt, _full_claims} 是调用 Guardian.encode_and_sign(user, :token) 返回的值。这是您链接到的教程中的原始代码：

{:ok, jwt, _full_claims} = user 
  |> Guardian.encode_and_sign(:token)

等同于：

{:ok, jwt, _full_claims} = Guardian.encode_and_sign(user, :token)

另一方面，您的代码执行 {:ok, jwt, _full_claims} = user 并且下一行是一个新语句。如果你想检查用户并仍然按照教程的方式进行，你可以这样做：

{:ok, jwt, _full_claims} = user
  |> IO.inspect
  |> Guardian.encode_and_sign(:token)

IO.inspect returns 打印后传递的值，因此此代码的功能与教程相同，只是它也会打印 user 的值。

无法理解 JWT 身份验证中的解构 (Phoenix)

Can't understand destructuring in JWT auth (Phoenix)

authentication

elixir

destructuring

jwt

phoenix-framework

这到底是什么意思：`{:ok, jwt, _full_claims} = user`？

无法理解 JWT 身份验证中的解构 (Phoenix)

Can't understand destructuring in JWT auth (Phoenix)

authentication

elixir

destructuring

jwt

phoenix-framework

这到底是什么意思：{:ok, jwt, _full_claims} = user？

这到底是什么意思：`{:ok, jwt, _full_claims} = user`？