Hologram: unable to make router work

Elixir Framework Forums Hologram Forum
,
1

Hi
I am trying to create a new app using hologram.

Erlang version: OTP 27
Elixir 1.18.0

I start with

mix phx.new insta --no-html --no-live --no-ecto

Then i follow the steps mentioned in the installation page

Then I create a folder call app/pages under the root folder insta
I add a home.ex file in the insta/app/pages folder

The file is -

defmodule Insta.HomePage do
  use Hologram.Page
  # alias Blog.Components.PostPreview
  
  route "/"
  
  # layout Blog.MainLayout
  
  def init(_params, component, _server) do
    posts = [
      %{id: 1, title: "First Post", excerpt: "This is my first post"},
      %{id: 2, title: "Second Post", excerpt: "Another great post"}
    ]
    
    put_state(component, :posts, posts)
  end

  def template do
    ~H"""
    <h1>Welcome to my Blog</h1>
    
    <div class="posts">
      {%for post <- @posts}
        <p>{post.title}</p>
      {/for}
    </div>
    """
  end
end

The app compiles fine, but I am not able to get anything on the route.
When i do mix holo.routes I get this -

07:35:46.980 [info] Hologram: compiler finished
--------------------------------------------------------------------------------
ROUTE / MODULE / SOURCE FILE
--------------------------------------------------------------------------------

Below is my endpoint file

defmodule InstaWeb.Endpoint do
  use Phoenix.Endpoint, otp_app: :insta
  use Hologram.Endpoint

  # The session will be stored in the cookie and signed,
  # this means its contents can be read but not tampered with.
  # Set :encryption_salt if you would also like to encrypt it.
  @session_options [
    store: :cookie,
    key: "_insta_key",
    signing_salt: "bvfPrVAO",
    same_site: "Lax"
  ]

  hologram_socket()

  # socket "/live", Phoenix.LiveView.Socket,
  #   websocket: [connect_info: [session: @session_options]],
  #   longpoll: [connect_info: [session: @session_options]]

  # Serve at "/" the static files from "priv/static" directory.
  #
  # You should set gzip to true if you are running phx.digest
  # when deploying your static files in production.
  plug Plug.Static,
    at: "/",
    from: :insta,
    gzip: false,
    only: ["hologram" | InstaWeb.static_paths()]

  # Code reloading can be explicitly enabled under the
  # :code_reloader configuration of your endpoint.
  if code_reloading? do
    plug Phoenix.CodeReloader
  end

  plug Phoenix.LiveDashboard.RequestLogger,
    param_key: "request_logger",
    cookie_key: "request_logger"

  plug Plug.RequestId
  plug Plug.Telemetry, event_prefix: [:phoenix, :endpoint]

  plug Plug.Parsers,
    parsers: [:urlencoded, :multipart, :json],
    pass: ["*/*"],
    json_decoder: Phoenix.json_library()

  plug Plug.MethodOverride
  plug Plug.Head
  plug Plug.Session, @session_options
  plug Hologram.Router
  # plug InstaWeb.Router
end

Please advise.

3 Likes
2

Hey @sreyansjain,
I noticed that the layout module is commented out in your page. This is required. Hologram will raise a compilation error if a page doesn’t have a layout specified - is this the actual code you use?
The layout needs to include the Hologram.UI.Runtime component which handles rendering the runtime and page JS bundles. Without the Runtime component, your page won’t be properly initialized.

1 Like
3

Yes, its the actual code I am using
I have added the layout module

defmodule Insta.MainLayout do
  use Hologram.Component
  
  alias Hologram.UI.Link
  alias Hologram.UI.Runtime
  
  def template do
    ~H"""
    <!DOCTYPE html>
    <html lang="en">
      <head>
        <meta charset="utf-8" />
        <title>My Blog</title>
        <Runtime />
      </head>
      <body>
        <nav>
          <Link to={Insta.HomePage}>Home</Link>
        </nav>
        <main>
          <slot />
        </main>
      </body>
    </html>
    """
  end
end

I have uncommented the layout section in the page home.ex

defmodule Insta.HomePage do
  use Hologram.Page
  # alias Insta.Components.PostPreview
  
  route "/"
  
  layout Insta.MainLayout
  
  def init(_params, component, _server) do
    posts = [
      %{id: 1, title: "First Post", excerpt: "This is my first post"},
      %{id: 2, title: "Second Post", excerpt: "Another great post"}
    ]
    
    put_state(component, :posts, posts)
  end

  def template do
    ~H"""
    <h1>Welcome to my Blog</h1>
    
    <div class="posts">
      {%for post <- @posts}
        <p>{post.title}</p>
      {/for}
    </div>
    """
  end
end

There are no compilation errors. Also there were no compilation errors before adding the layout.

I dont get any routes.

When i do

mix holo.routes

I get

19:13:58.847 [info] Hologram: compiler finished
--------------------------------------------------------------------------------
ROUTE / MODULE / SOURCE FILE
--------------------------------------------------------------------------------

If I run the project there are no compilation errors, but there are no routes

[info] GET /
[error] #PID<0.2725.0> running Phoenix.Endpoint.SyncCodeReloadPlug (connection #PID<0.2724.0>, stream id 1) terminated

Were are the routes defined? In the page itself?

4

Looks like you forgot to add something to your app. Please make sure that you follow installation instructions especially the parts of endpoint and router:
https://hologram.page/docs/installation

2 Likes
5

If this is just a hobby/tinkering project, can you share the GitHub repo?

6

Its just a new phoenix project with nothing in it except what should go in for hologram.

mix phx.new insta --no-html --no-live --no-ecto

You can download here

1 Like
7

I rechecked. I think I have followed the steps mentioned. There’s no error on compiling.

1 Like
8

Thanks, the problem is that you added your app dir outside the lib dir. If you want it to work that way you need to add the app dir to Elixir compile paths:

in your mix.exs:

defp elixirc_paths(:test), do: ["app", "lib", "test/support"]
defp elixirc_paths(_), do: ["app", "lib"]
6 Likes
9

Works. Actually I saw the app folder in the hologram/test/features project so i thought code needs to go in the app folder, but overlooked the paths.

Thank you so much for your time.

1 Like
10

No worries, happy tinkering :slight_smile:

1 Like