Ecto field convert a map to text and text to map [elixir :map -> postgres :text -> elixir :map]

map_to_text.ex

# Into ecto migration "add :my_field, :text"
# Into ecto schema "field :my_field, MapToText"

defmodule MapToText do
  use Ecto.Type
  def type, do: :map

  def cast(data) when is_map(data), do: {:ok, data}
  def cast(_), do: :error

  def load(data) when is_binary(data), do: Jason.decode(data)
  def load(_), do: :error

  def dump(data) when is_map(data), do: Jason.encode(data)
  def dump(_), do: :error
end