How to convert map keys from strings to atoms in Elixir

Question

What is the way to convert %{\"foo\" => \"bar\"} to %{foo: \"bar\"} in Elixir?

Answer 1

Snippet below converts keys of nested json-like map to existing atoms:

iex(2)> keys_to_atoms(%{"a" => %{"b" => [%{"c" => "d"}]}})

%{a: %{b: [%{c: "d"}]}}

  def keys_to_atoms(json) when is_map(json) do
    Map.new(json, &reduce_keys_to_atoms/1)
  end

  def reduce_keys_to_atoms({key, val}) when is_map(val), do: {String.to_existing_atom(key), keys_to_atoms(val)}
  def reduce_keys_to_atoms({key, val}) when is_list(val), do: {String.to_existing_atom(key), Enum.map(val, &keys_to_atoms(&1))}
  def reduce_keys_to_atoms({key, val}), do: {String.to_existing_atom(key), val}