exmr/lib/exmr_web/live/exam_live/form_component.ex

defmodule ExmrWeb.ExamLive.FormComponent do
  use ExmrWeb, :live_component

  alias Exmr.Exams

  @impl true
  def render(assigns) do
    ~H"""
    <div>
      <.header>
        {@title}
        <:subtitle>
          {gettext("Use this form to manage exam records in your database.")}
        </:subtitle>
      </.header>

      <.simple_form
        for={@form}
        id="exam-form"
        phx-target={@myself}
        phx-change="validate"
        phx-submit="save"
      >
        <.input field={@form[:subject]} type="text" label={gettext("Subject")} />
        <.input field={@form[:description]} type="text" label={gettext("Description")} />
        <.input field={@form[:date]} type="date" label={gettext("Date")} />
        <:actions>
          <.button phx-disable-with={gettext("Saving...")}>{gettext("Save Exam")}</.button>
        </:actions>
      </.simple_form>
    </div>
    """
  end

  @impl true
  def update(%{exam: exam} = assigns, socket) do
    {:ok,
     socket
     |> assign(assigns)
     |> assign_new(:form, fn ->
       to_form(Exams.change_exam(exam))
     end)}
  end

  @impl true
  def handle_event("validate", %{"exam" => exam_params}, socket) do
    changeset = Exams.change_exam(socket.assigns.exam, exam_params)
    {:noreply, assign(socket, form: to_form(changeset, action: :validate))}
  end

  def handle_event("save", %{"exam" => exam_params}, socket) do
    save_exam(socket, socket.assigns.action, exam_params)
  end

  defp save_exam(socket, :edit, exam_params) do
    case Exams.update_exam(socket.assigns.exam, exam_params) do
      {:ok, exam} ->
        notify_parent({:saved, exam})

        {:noreply,
         socket
         |> put_flash(:info, "Exam updated successfully")
         |> push_patch(to: socket.assigns.patch)}

      {:error, %Ecto.Changeset{} = changeset} ->
        {:noreply, assign(socket, form: to_form(changeset))}
    end
  end

  defp save_exam(socket, :new, exam_params) do
    case Exams.create_exam(exam_params) do
      {:ok, exam} ->
        notify_parent({:saved, exam})

        {:noreply,
         socket
         |> put_flash(:info, "Exam created successfully")
         |> push_patch(to: socket.assigns.patch)}

      {:error, %Ecto.Changeset{} = changeset} ->
        {:noreply, assign(socket, form: to_form(changeset))}
    end
  end

  defp notify_parent(msg), do: send(self(), {__MODULE__, msg})
end