jshprentz

jshprentz

Phoenix in Action book: Running the code in 2023

Geoffrey Lessel’s 2019 book, Phoenix in Action, was written for Phoenix 1.4.
I found that the book’s code examples did not match the current Phoenix 1.7 web application structure.
Reverting to Phoenix 1.6, I was able to build, run, and test the example Auction Web application.

As I worked through the book, I made the following changes to accomodate Phoenix 1.6:

6.1 Installing Phoenix on your system

Install the latest version of Phoenix 1.6.

mix archive.install hex phx_new 1.6.16

6.2 Creating a new Phoenix application

Phoenix 1.6 applications include a mailer by default.
The auction project does not need it.
When generating the auction_web application, omit the mailer with this command.

mix phx.new.web auction_web --no-ecto --no-mailer

Listing 6.3 shows adding this line to configure Phoenix to use Jason.

config :phoenix, :json_library, Jason

Phoenix 1.6 generates that line automatically; there is no need to add it.

6.2.1 Running your server for the first time

The “good news” also includes this advice:

Your web app requires a PubSub server to be running.
The PubSub server is typically defined in a `mix phx.new.ecto` app.
If you don't plan to define an Ecto app, you must explicitly start
the PubSub in your supervision tree as:

    {Phoenix.PubSub, name: AuctionWeb.PubSub}

That line should be added to the list of children in
auction_umbrella/apps/auction_web/lib/auction_web/application.ex:

  @impl true
  def start(_type, _args) do
    children = [
      {Phoenix.PubSub, name: AuctionWeb.PubSub},
      # Start the Telemetry supervisor
      AuctionWeb.Telemetry,
      # Start the Endpoint (http/https)
      AuctionWeb.Endpoint
      # Start a worker by calling: AuctionWeb.Worker.start_link(arg)
      # {AuctionWeb.Worker, arg}
    ]

Running the web server without this line results in a barrage of log messages such as:

08:55:41.210 [error] GenServer #PID<0.629.0> terminating
** (ArgumentError) unknown registry: AuctionWeb.PubSub
...

When first run, phx.server complained:

>mix phx.server
warning: the :gettext compiler is no longer required in your mix.exs.

Please find the following line in your mix.exs and remove the :gettext entry:

    compilers: [..., :gettext, ...] ++ Mix.compilers(),

I deleted :gettext from this line in auction_umbrella\apps\auction_web\mix.exs:

    compilers: [:gettext] ++ Mix.compilers(),

10.4 Adding site navigation

In Phoenix 1.6, root.html.hexx contains the HTML boilerplate, including the <header>.
That file has a placeholder, @inner_content, for the contents of app.html.heex,
which provides two alerts and references additional @inner_content.
The site navigation can be added before those alerts.

11.3.3 Adding the list of bids to the view template

In Listing 11.21, item_bid_path should be Routes.item_bid_path in this line:

        <%= form_for @bid, item_bid_path(@conn, :create, @item), fn f -> %>

12.2 Connecting a user to a channel and a topic

The Phoenix app was missing user_socket.ex. Create it with these commands:

>cd auction_umbrella\apps\auction_web
>mix phx.gen.socket User

Follow the resulting instructions to add the socket handler to your lib/auction_web/endpoint.ex, for example:

    socket "/socket", AuctionWeb.UserSocket,
      websocket: true,
      longpoll: false

12.2.2 Getting the user’s browser to join a topic

With Phoenix 1.6, the socket.js file is named user_socket.js.

Listing 12.4 shows the automatically generated channel topic:subtopic.
Phoenix 1.6 instead generates the channel room:42.

In Listing 12.6, also uncomment this line near the beginning of the file:

// import "./user_socket.js"

12.4.1 Refactoring the rendering of an item’s bids

The code in Listing 12.12 must be saved in bid.html.eex, not bid.html.heex.

Phoenix 16 introduced a new HTML engine that uses HTML-aware template files
(HEEx: HTML Embedded Elixir).
I did not initially notice that many automatically generated templates had the
.heex extension.

See Phoenix 1.6.0-rc.0 released!
for a description of HEEx templates.

See Phoenix.View.render_many can't render .leex templates · Issue #3952 · phoenixframework/phoenix · GitHub
for a discussion of render_many and HEEx files.

14.4.3 Viewing documentation with ExDoc

Add a project name to auction_umbrella/mix.exs:

  def project do
    [
      name: "Auction Umbrella",
      apps_path: "apps",
      version: "0.1.0",
      start_permanent: Mix.env() == :prod,
      deps: deps()
    ]
  end

14.4.4 Adding examples and doctests

In the first example in Listing 14.22, start the second line with ...> and correct the double quotes
around the password confirmation value.

    iex> insert_user(%{username: "geo", password: "example",
    ...> password_confirmation: "example", email_address: "test@example.com"})
    ...> result = get_user_by_username_and_password("geo", "example")
    ...> match?(%Auction.User{username: "geo"}, result)
    true

14.5 Writing tests For Phoenix

The test runner displayed this error instead of the error shown in Listing 14.25:

  1) test GET / (AuctionWeb.PageControllerTest)
     apps/auction_web/test/auction_web/controllers/page_controller_test.exs:4
     ** (ArgumentError) cookie store expects conn.secret_key_base to be set
     code: conn = get(conn, "/")
     stacktrace: ...

Fix by adding a secret_key_base to the test.exs auction web endpoint:

config :auction_web, AuctionWeb.Endpoint,
  secret_key_base: "Dzlf6LT5j14IS16DQHviw2OuMiNjHBGGkrCDe8fMbR41Us/RMCPQfWzkigWa7Ags"

Next, the test runner displayed this error instead of that shown in Listing 14.25:

  1) test GET / (AuctionWeb.PageControllerTest)
     apps/auction_web/test/auction_web/controllers/page_controller_test.exs:4
     ** (DBConnection.OwnershipError) cannot find ownership process for #PID<0.627.0>.

     When using ownership, you must manage connections in one
     of the four ways:

     * By explicitly checking out a connection
     * By explicitly allowing a spawned process
     * By running the pool in shared mode
     * By using :caller option with allowed process

     ...

Fix by modifying auction_web/test/support/conn_case.ex to
checkout Auction.Repo in a sandbox and set its mode to shared.
Replace the setup _tags do section with:

  setup tags do
    :ok = Ecto.Adapters.SQL.Sandbox.checkout(Auction.Repo)

    unless tags[:async] do
      Ecto.Adapters.SQL.Sandbox.mode(Auction.Repo, {:shared, self()})
    end

    {:ok, conn: Phoenix.ConnTest.build_conn()}
  end

Most Liked

geo

geo

Author of Phoenix in Action

This is awesome! Thank you for putting this up here.

7stud

7stud

Thanks for this post!!! I have been searching all over for:

(ArgumentError) unknown registry: AuctionWeb.PubSub

After a 1.5 days of searching and trying all kinds of things, I finally found your post.

I wish you could edit the title of your post to add:

(ArgumentError) unknown registry: AuctionWeb.PubSub

That is probably the first error someone is going to encounter when following the book, then they would find the rest of your post. I’ll leave some breadcrumbs at other places I was searching.

Somewhere I found something that said that adding:

{Phoenix.PubSub, name: AuctionWeb.PubSub},

should be above:

AuctionWeb.Endpoint

Thanks for taking the time to write this post. So helpful!

I’m using Phoenix Framework v1.7.10, and I’ll keep forging ahead to see how far I can get. :face_with_monocle:

7stud

7stud

Some more info about the AuctionWeb.PubSub problem here:

I got my database set up (it’s still empty), and everything is working well. Anything the book said to put in a config.exs file, I put it in auction_umbrella/config/config.exs.

I finished chapter 7, and everything is working error/warning free. My database has several items in it, and they are displayed on the web page.

[prevented from showing image here, oh well]

On to chapter 8 and changesets.

My full setup:

 $ asdf list erlang
  24.3.4
 *26.1.2

 $ asdf list elixir
  1.13.4
  1.14.4-otp-24
 *1.16.0-rc.1-otp-26

phoenix v1.7.10

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