Helper function for put_in for populating data in deep maps.

helper.ex

defmodule Helper do

  # Helper function for setting values deep in a map.
  # Thanks @michalmuskala!
  # https://elixirforum.com/t/put-update-deep-inside-nested-maps-and-auto-create-intermediate-keys/7993/8
  
  @doc """
    Will set value at for keys deep inside data.
    
    iex> Helper.put_in_deep(%{a: %{}}, [:a, :b, :c], 42)
    %{a: %{b: %{c: 42}}}
  """
  defp put_in_deep(data, keys, value) when is_list(keys) do
    put_in(data, Enum.map(keys, &Access.key(&1, %{})), value)
  end

end

FWIW, less elegant but working for keywords and lists solution: https://hexdocs.pm/iteraptor/Iteraptor.Extras.html#bury/4