customer-service/lib/customer_service/aggregates/customer_id.ex

defmodule CustomerService.Aggregates.CustomerId do
  @type t :: %__MODULE__{
          org_id: String.t(),
          customer_type: String.t(),
          customer_id: String.t()
        }
  @derive Jason.Encoder
  defstruct [:org_id, :customer_type, :customer_id]

  def new(org_id, customer_type, customer_id)
      when is_binary(org_id) and is_binary(customer_type) and is_binary(customer_id) do
    %__MODULE__{
      org_id: org_id,
      customer_type: customer_type,
      customer_id: customer_id
    }
  end

  def parse(<<_::binary>> = string) do
    case String.split(string, ":", parts: 3) do
      [org_id, customer_type, customer_id] ->
        {:ok, %__MODULE__{org_id: org_id, customer_type: customer_type, customer_id: customer_id}}

      _ ->
        {:error, :invalid_customer_id}
    end
  end

  def parse! do
    {:error, :invalid_customer_id}
  end

  defimpl String.Chars do
    def to_string(%CustomerService.Aggregates.CustomerId{
          org_id: org_id,
          customer_type: type,
          customer_id: customer_id
        }) do
      org_id <> ":" <> type <> ":" <> customer_id
    end
  end

  defimpl Commanded.Serialization.JsonDecoder do
    def decode(%{org_id: org_id, customer_type: customer_type, customer_id: customer_id}) do
      CustomerService.Aggregates.CustomerId.new(org_id, customer_type, customer_id)
    end

    def decode(id), do: id
  end
end