layout_view.ex

defmodule Myproject.LayoutView do
  use Myproject.Web, :view

  defp render_flash(type, message) do
    ~E"""
    <div class="alert alert-<%= type %>" role="alert">
      <%= message %>
      <button type="button" class="close" data-dismiss="alert" aria-label="Close">
        <span aria-hidden="true">&times;</span>
      </button>
    </div>
    """
  end

  def show_flash(conn) do
    case get_flash(conn) do
      %{"info" => msg} ->
        render_flash("info", msg)
      %{"error" => msg} ->
        render_flash("danger", msg)
      _ ->
        ""
    end
  end
end