Change socket.assigns.form.params in phx-blur handler

Phoenix Forum Questions / Help
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1

I am building form with liveview component, where I need change value of some inputs, after user leave input. I’ve used phx-blur on this input and handle_event. Event happens, I change socket.assigns.form.params. Other input will change correctly, but the one input with phx-blur will not. Anyone have any idea why?

2

I use .form and .input from the generated core_components.ex.

3

Can you share some code as I don’t quite understand. You’re saying blur does trigger handle_event but then doesn’t?

As a shot in the dark, are you changing socket.assigns.form.params directly? You definitely should not be doing that.

4

Thank you for fast response. I apologize for my lousy English.

Yes, I change socket.assigns.form.params directly:

def handle_event("event_blur", _params, socket) do
  socket =
      assign(socket, :form, %{
        socket.assigns.form
        | params: %{socket.assigns.form.params | "url" => "new value", "title" => ""}
      })

  {:noreply, socket}
end

What is the recommended method for changing form values from event handlers?

5

Hey, sorry for the delay in reply now—I just checked out Elixir Forum quickly before going out and no worries re English! I was just a bit confused.

I’m still not 100% sure what you’re aiming to accomplish but I think you want something like this:

socket =
  update(socket, :form, fn %{source: changeset} ->
    changeset
    |> Ecto.Changeset.put_change(:url, "new value")
    |> Ecto.Changeset.put_change(:title, "")
    |> to_form()
  end)

It’s ok to access :params but they shouldn’t be updated as they are meant to represent the data given on changeset creation which is uncast data, ie, its contents are not be trusted.

6

It works. Thanks a lot.

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