user_util.ex

defmodule UserUtil do
  def list do
    {:atomic, records} =
      :mnesia.transaction(fn ->
        :mnesia.match_object({:user_info, :_, :_})
      end)
    Enum.map(records, fn {:user_info, username, _password} -> username end)
  end
  
  def delete(username) do
    {:atomic, _} =
      :mnesia.transaction(fn ->
        # First delete the user information
        :mnesia.delete({:user_info, username})
        
        # Also delete the save data
        :mnesia.match_object({:user_savedata, {username, :_}, :_})
        |> Enum.each(fn {:user_savedata, key, _} ->
          :mnesia.delete({:user_savedata, key})
        end)
      end)
  end
end