Maybe you have some state update that gets unintentionally discarded? I.e. you do some computation but then forget to update the socket and return the updated state.
I’ve seen it happen sometimes 
rhcarvalho
jberling
jberling
I’ve not been this lost as a developer in ages. Nothing has worked for me today.
I’ve created an example. This code is totally f*cked upp.
There is a counter that is incremented every time you edit your answers.
It is also incremented if you hit the inc button or when you hit evaluate.
But here is the strange thing. There seems to be one counter for when you edit your answers, and one for when you hit one of the buttons. So if I edit the answer 4 times, the counter will be at 4. If I on the other hand hit inc or evaluate, it starts from 0. Let’s say I hit a button 2 times, then the counter will be 2. If I edit the answer it becomes 5. If I hit a button 3 … I’m completely lost.
I am sure I am doing some stupid mistake, but I can’t see it. I’m blind.
And exhausted.
defmodule CopyWeb.StrangeEditor do
@moduledoc false
use CopyWeb, :live_component
def render(assigns) do
~H"""
<div class="pb flow">
<.simple_form for={@form} phx-change="update" phx-submit="evaluate" phx-target={@myself}>
<h2>{@question}</h2>
<div class="wrap-grid">
<.input type="textarea" field={@form[:answer]} phx-debounce="750" />
<div data-ddi-variant="brand">{@evaluation}</div>
</div>
<.button>Evaluate</.button>
</.simple_form>
<.button phx-click="inc" phx-target={@myself}>Inc</.button>
</div>
"""
end
def handle_event(
"inc",
_params,
socket
) do
send(self(), {:inc})
{:noreply, socket}
end
def handle_event(
"evaluate",
_,
%{assigns: %{id: id}} = socket
) do
evaluation = "Score: #{:rand.uniform(10)}"
send(self(), {:evaluate, id, evaluation})
{:noreply, socket}
end
def handle_event("update", %{"answer" => answer}, %{assigns: %{id: id}} = socket) do
send(self(), {:updated_answer, id, answer})
{:noreply, socket}
end
end
defmodule CopyWeb.StrangeViewLive do
@moduledoc false
use CopyWeb, :live_view
alias CopyWeb.StrangeEditor
def mount(_params, _session, socket) do
socket =
assign(socket,
questionnaire: [
%{id: "color", question: "favourite color?", form: to_form(%{"answer" => ""})},
%{id: "food", question: "favourite food?", form: to_form(%{"answer" => ""})},
%{id: "animal", question: "favourite animal?", form: to_form(%{"answer" => ""})}
],
answers: %{},
evaluations: %{},
counter: 0
)
{:ok, socket}
end
def handle_info({:inc}, socket) do
counter = Map.get(socket.assigns, :counter, 0)
{:noreply, assign(socket, counter: counter + 1)}
end
def handle_info({:evaluate, question_id, evaluation}, socket) do
counter = Map.get(socket.assigns, :counter, 0)
socket =
assign(socket,
evaluations: Map.put(socket.assigns.evaluations, question_id, evaluation),
counter: counter + 1
)
{:noreply, socket}
end
def handle_info({:updated_answer, question_id, answer}, socket) do
counter = Map.get(socket.assigns, :counter, 0)
{:noreply,
assign(socket,
answers: Map.put(socket.assigns.answers, question_id, answer),
counter: counter + 1
)}
end
def render(assigns) do
~H"""
<main class="p" data-ddi-variant="normal">
<div>counter: {@counter}</div>
<.live_component
:for={item <- @questionnaire}
module={StrangeEditor}
id={item.id}
question={item.question}
answer={Map.get(@answers, item.id, "")}
form={item.form}
evaluation={Map.get(@evaluations, item.id, "")}
/>
</main>
"""
end
end
0
jberling
I’m continuing debugging the issue. The transport_id of the socket is the same in the handle_info calls for :inc and :evaluate, but for :update_answer it is different. This confirm the suspicion somehow the button clicks are handled differently than the input change.
I don’t understand what this means though.
0
kklisura
I’ve tried this and I don’t get this problem. Everything looks good: when I click the buttons, counter increases, when I enter text, counter increases… What am I now doing wrong? 
Full repo here https://github.com/kklisura/copy-web-test-app (just created new project with mix phx.new)
1
jberling
First, thanks a lot for helping me! Secondly, how clever of you to create a git-repository. I should have done that as well.
The example doesn’t behave as in my original repo for some reason. In your repo, the counter is updated as it should be, and the transport_pid is the same in the socket for all handle_info calls.
Unfortunately, the text in the input is still cleared when you hit “evaluate,” though. I’ll investigate why.
0
jberling
I fixed some logical errors, and now everything works as it should in the repo you created.
https://github.com/kklisura/copy-web-test-app/commit/aa23d2b22d9c957bd1d932f250933f1af96e13c9
How strange. Well, I guess I’ll continue to dig deeper into my real project.
2
FlyingNoodle
Are you sure that you aren’t encountering an issue in your code and your liveview reloads (which produces a new connection id?)
0
jberling
I don’t think that is the issue, because it will jump between two different transport_pids, not different ones every time. And if it reload, doesn’t it create a completely new LiveView socket?
0
jberling
I have found the source of the strange state issues.
In copy_web.ex I’d changed from the :app layout to the :root layout. If I change it back to :app, my problems disappear. I have not yet figured out why though.
def live_view do
quote do
use Phoenix.LiveView,
layout: {CopyWeb.Layouts, :root}
import PhoenixLiveReact
unquote(html_helpers())
end
end
2