hoetmaaiers

hoetmaaiers

I want to redirect the Phoenix router to a specific page so “/” renders the first navigation item.

Currently I do this using a root page:

# router.ex
defmodule AppWeb.Router do
   ...
  scope "/", AppWeb do
    pipe_through :browser



    live_session :navigation, on_mount: [AppWeb.Navigation] do
      live "/", RootLive.Index
      live "/comics", ComicLive.Index
      live "/comics/new", ComicLive.New, :new
      live "/comics/:id", ComicLive.Show, :edit
      ...

In RootLive.index this happens:

defmodule StripeljeeWeb.RootLive.Index do
  use StripeljeeWeb, :live_view

  def handle_params(_unsigned_params, _uri, socket) do
    {:noreply, socket |> redirect(to: "/comics")}
  end

  def render(assigns) do
    ~H"""
    ...
    """
  end
end

This does work, but Dializer complains about this:

Type mismatch for @callback mount/3 in Phoenix.LiveView behaviour.

Expected type:

  {:ok,
   %Phoenix.LiveView.Socket{
     :assigns => Phoenix.LiveView.Socket.assigns_not_in_socket() | map(),
     :endpoint => atom(),
     :fingerprints => {nil | binary(), map()},
     :host_uri =>
       :not_mounted_at_router
       | %URI{
           :authority => URI.authority(),
           :fragment => nil | binary(),
           :host => nil | binary(),
           :path => nil | binary(),
           :port => nil | char(),
           :query => nil | binary(),
           :scheme => nil | binary(),
           :userinfo => nil | binary()
         },
     :id => binary(),
     :parent_pid => nil | pid(),
     :private => map(),
     :redirected => nil | tuple(),
     :root_pid => pid(),
     :router => atom(),
     :transport_pid => nil | pid(),
     :view => atom()
   }}
  | {:ok,
     %Phoenix.LiveView.Socket{
       :assigns => Phoenix.LiveView.Socket.assigns_not_in_socket() | map(),
       :endpoint => atom(),
       :fingerprints => {nil | binary(), map()},
       :host_uri =>
         :not_mounted_at_router
         | %URI{
             :authority => URI.authority(),
             :fragment => nil | binary(),
             :host => nil | binary(),
             :path => nil | binary(),
             :port => nil | char(),
             :query => nil | binary(),
             :scheme => nil | binary(),
             :userinfo => nil | binary()
           },
       :id => binary(),
       :parent_pid => nil | pid(),
       :private => map(),
       :redirected => nil | tuple(),
       :root_pid => pid(),
       :router => atom(),
       :transport_pid => nil | pid(),
       :view => atom()
     }, Keyword.t()}


Actual type:

  {:noreply,
   %Phoenix.LiveView.Socket{
     :redirected => {:redirect, map()} | {:live, :patch | :redirect, map()},
     _ => _
   }}

Showing Posts 1 to 8

D4no0

D4no0

The mount/3 callback should return data in format {:ok, socket} not how you would do when handling an event: {:noreply, socket}.

hoetmaaiers

hoetmaaiers OP

Sorry, but how does this relate? I try to understand but can’t.

When defining a mount callback like this:

  def mount(_params, _session, socket) do
    {:ok, socket}
  end

The warning from dialyzer is not much different:

Type mismatch for @callback mount/3 in Phoenix.LiveView behaviour.

Expected type:

  {:ok,
   %Phoenix.LiveView.Socket{
     :assigns => Phoenix.LiveView.Socket.assigns_not_in_socket() | map(),
     :endpoint => atom(),
     :fingerprints => {nil | binary(), map()},
     :host_uri =>
       :not_mounted_at_router
       | %URI{
           :authority => URI.authority(),
           :fragment => nil | binary(),
           :host => nil | binary(),
           :path => nil | binary(),
           :port => nil | char(),
           :query => nil | binary(),
           :scheme => nil | binary(),
           :userinfo => nil | binary()
         },
     :id => binary(),
     :parent_pid => nil | pid(),
     :private => map(),
     :redirected => nil | tuple(),
     :root_pid => pid(),
     :router => atom(),
     :transport_pid => nil | pid(),
     :view => atom()
   }}
  | {:ok,
     %Phoenix.LiveView.Socket{
       :assigns => Phoenix.LiveView.Socket.assigns_not_in_socket() | map(),
       :endpoint => atom(),
       :fingerprints => {nil | binary(), map()},
       :host_uri =>
         :not_mounted_at_router
         | %URI{
             :authority => URI.authority(),
             :fragment => nil | binary(),
             :host => nil | binary(),
             :path => nil | binary(),
             :port => nil | char(),
             :query => nil | binary(),
             :scheme => nil | binary(),
             :userinfo => nil | binary()
           },
       :id => binary(),
       :parent_pid => nil | pid(),
       :private => map(),
       :redirected => nil | tuple(),
       :root_pid => pid(),
       :router => atom(),
       :transport_pid => nil | pid(),
       :view => atom()
     }, Keyword.t()}


Actual type:

  {:noreply,
   %Phoenix.LiveView.Socket{
     :redirected => {:redirect, map()} | {:live, :patch | :redirect, map()},
     _ => _
   }}


D4no0

D4no0

If you have changed the code and the warning still persists, try to delete the _build folder and start the server again, sometimes there are cache bugs.

sodapopcan

sodapopcan

This line looks wrong. Unless there is a default identifier you can use that I don’t about, it should either look like: on_mount: [{AppWeb.Navigation, :some_identifier}] or just on_mount: {AppWeb.Navigation, :some_identifier} if you only have one callback.

hoetmaaiers

hoetmaaiers OP

@D4no0 this makes no difference. Restarting the Elixir language server also solves nothing. Running mix phx.server does not show this error, only ElixirLS shows the warning.

If you have changed the code and the warning still persists, try to delete the _build folder and start the server again, sometimes there are cache bugs.

@sodapopcan I looked into this through the documentation and I indeed use the :default identifier.

LostKobrakai

LostKobrakai

The error still lists the actual type as {:noreply, …}, where {:ok, …} is expected. So that’s what you should be looking out for.

D4no0

D4no0

You should have started with the fact that the problem comes from ElixirLS, the build folder for elixir-ls for vscode is located in .elixir_ls. What I do in such cases is close code editor, remove _build, .elixir_ls and then it should compile everything from a clear start.

I’ve been also noticing having a lot of times this happen lately, maybe a bug introduced in some update, hopefully it will be fixed soon.

hoetmaaiers

hoetmaaiers OP

Thank you for pointing out that elixir_ls has its own .elixir_ls folder. Deleting this solved its complaints.

— All posts loaded —

Where Next? Top

Trending in Questions Top

katta
I having some trouble figuring out if I have set myself too strict of standards for my production server. Currently I can handle 75% of r...
New
brecabral
Documentation While reading the Scoped Routes section, I noticed that the documentation currently refers to a problem without explainin...
New
achenet
Hello, I’m trying to build a basic Phoenix web-app, and I’d like to use Tailwind. However, when I launch mix phx.server, I get an error...
New
kpanic
Hi everyone, I am toying with the idea of building a “match maker” for giving personal help to people that wants to start coding. I sta...
New
asweet-confluent
I recently noticed that Elixir’s Logger defaults its primary log level to :debug when no :logger, :level application configuration is pre...
New
Cxx-mlr
I’m working on a small exercise involving update_in/3, and I came up with this solution: data = %{ name: "Periodic Table", category:...
New
ChrisAmelia
I’ve got trouble wrapping my head around the order in which functions are called in this snippet (from Phoenix’s authentication): toke...
New

Other Trending Topics Top

GenericJam
Edit: 2026 May 15 - This post is archived. Mob is alive!! Main docs: mob v0.7.11 — Documentation A bit of explanation for the slightly c...
New
JesseHerrick
Hey, I’m Jesse and I’m the main contributor behind Dexter, a full-featured, lightning-fast Elixir LSP optimized for large codebases. It s...
New
mudasobwa
I am happy to introduce the very α version of the new programming language compiled to BEAM. Welcome Cure. It has literally three kille...
New
garrison
Hobbes is a low-level distributed database for the Elixir programming language. Hobbes provides a simple, safe, and scalable storage lay...
New
mhanberg
Hi everyone! The first release candidate for the Expert language server project is now available! We’ve published a press release detai...
New
budgie
A little off-topic, but I feel like people here have a good head on their shoulders. I used to be quite good at making software. Was luc...
New

We're in Beta

About us Mission Statement

Options

Thread Display Mode




Thread Preview

Skip Thread Previews