It should be OK since you’re only setting the ID on mount and the submit event. I also used a Hook to reset the field before I went back to the phx-change because the Hook felt like duct tape instead of a real solution.
I’m curious about the costs with using phx-change because I’m using it a lot on a new project 
I realized I completely read past the meaning of “random” in your original reply so sorry if my replies sounded inconsistent (I figured you meant a random hardcoded ID).
It still seems a bit cavalier to use a totally random one but maybe it’s fine if it’s just the form? I’m trying to think of a scenario where the form would re-render and the ID would change. But ya… I can’t atm.
I tried a couple of things, and changing the id is the only thing that worked for:
def handle_event("add", %{"entry" => params}, socket) do
case Paste.Entries.create_entry(params) do
{:ok, entry} ->
{:noreply,
socket
|> put_flash(:info, "entry #{entry.id} added")
|> assign(
form: to_form(
Entries.change_entry(%Entry{}),
id: "form-#{System.unique_integer()}"
)
)
|> stream_insert(:entries, entry, at: 0)}
{:error, %Ecto.Changeset{} = changeset} ->
{:noreply, assign(socket, form: to_form(changeset))}
end
end