Hello all:
I have a problem in phoenix project. The official example I use is for creating users, project error
This is an error log
[debug] Converted error Protocol.UndefinedError to 500 response
[error] #PID<0.804.0> running StoreApiWeb.Endpoint (connection #PID<0.803.0>, stream id 1) terminated
Server: localhost:4004 (http)
Request: POST /user
** (exit) an exception was raised:
** (Protocol.UndefinedError) protocol Phoenix.HTML.Safe not implemented for %{errors: %{detail: "Internal Server Error"}} of type Map. This protocol is implemented for the following type(s): Atom, BitString, Date, DateTime, Decimal, Float, Integer, List, NaiveDateTime, Phoenix.HTML.Form, Phoenix.LiveComponent.CID, Phoenix.LiveView.Component, Phoenix.LiveView.Comprehension, Phoenix.LiveView.JS, Phoenix.LiveView.Rendered, Time, Tuple
it is my case
router.ex
defmodule StoreApiWeb.Router do
use StoreApiWeb, :router
pipeline :api do
plug :accepts, ["json"]
end
scope "/api", StoreApiWeb do
pipe_through :api
end
pipeline :browser do
plug(:accepts, ["html", "json"])
end
scope "/user", StoreApiWeb do
pipe_through :browser
# 获取所有用户信息
resources "/", UserController, except: [:new, :edit]
# 新增用户
post "/user_create", UserController, :user_create
post "/sign_in", UserController, :sign_in
post "/update", UserController, :update
get "/detail", UserController, :show
end
# Enables LiveDashboard only for development
#
# If you want to use the LiveDashboard in production, you should put
# it behind authentication and allow only admins to access it.
# If your application does not have an admins-only section yet,
# you can use Plug.BasicAuth to set up some basic authentication
# as long as you are also using SSL (which you should anyway).
if Mix.env() in [:dev, :test] do
import Phoenix.LiveDashboard.Router
scope "/" do
pipe_through [:fetch_session, :protect_from_forgery]
live_dashboard "/dashboard", metrics: StoreApiWeb.Telemetry
end
end
# Enables the Swoosh mailbox preview in development.
#
# Note that preview only shows emails that were sent by the same
# node running the Phoenix server.
if Mix.env() == :dev do
scope "/dev" do
pipe_through [:fetch_session, :protect_from_forgery]
forward "/mailbox", Plug.Swoosh.MailboxPreview
end
end
end
user_controller.ex
defmodule StoreApiWeb.UserController do
use StoreApiWeb, :controller
alias StoreApi.Accounts
alias StoreApi.Accounts.User
action_fallback StoreApiWeb.FallbackController
def index(conn, _params) do
users = Accounts.list_users()
render(conn, "index.json", users: users)
end
def create(conn, %{"user" => user_params}) do
with {:ok, %User{} = user} <- Accounts.create_user(user_params) do
conn
|> put_status(:created)
|> put_resp_header("location", Routes.user_path(conn, :show, user))
|> render("show.json", user: user)
end
end
def show(conn, %{"id" => id}) do
user = Accounts.get_user!(id)
render(conn, "show.json", user: user)
end
def update(conn, %{"id" => id, "user" => user_params}) do
user = Accounts.get_user!(id)
with {:ok, %User{} = user} <- Accounts.update_user(user, user_params) do
render(conn, "show.json", user: user)
end
end
def delete(conn, %{"id" => id}) do
user = Accounts.get_user!(id)
with {:ok, %User{}} <- Accounts.delete_user(user) do
send_resp(conn, :no_content, "")
end
end
def sign_in(conn, %{"name" => name, "tag" => tag}) do
case Accounts.authenticate_user(name, tag) do
{:ok, user} ->
conn
|> put_status(:ok)
|> put_view(StoreApiWeb.UserView)
|> render("sign_in.json", user: user)
{:error, message} ->
conn
|> put_status(:unauthorized)
|> put_view(StoreApiWeb.ErrorView)
|> render("401.json", message: message)
_ ->
conn
|> put_status(:syserror)
|> put_view(StoreApiWeb.ErrorView)
|> render("common.json", message: "系统错误！")
end
end
end
accounts.ex
defmodule StoreApi.Accounts do
@moduledoc """
The Accounts context.
"""
import Ecto.Query, warn: false
alias StoreApi.Repo
alias StoreApi.Accounts.User
@doc """
Returns the list of users.
## Examples
iex> list_users()
[%User{}, ...]
"""
def list_users do
Repo.all(User)
end
@doc """
Gets a single user.
Raises `Ecto.NoResultsError` if the User does not exist.
## Examples
iex> get_user!(123)
%User{}
iex> get_user!(456)
** (Ecto.NoResultsError)
"""
def get_user!(id), do: Repo.get!(User, id)
def create_user(attrs \\ %{}) do
%User{}
|> User.changeset(attrs)
|> Repo.insert()
end
end
After I start the service, use Postman to access http://localhost:4004/user , an error is reported, but the database has been updated
thank you very much indeed 
