iex> Ksuid.generate()
"0p9kxW1vWavpdq7VSgbv8piY0nr"

iex> Ksuid.parse("0p9kxW1vWavpdq7VSgbv8piY0nr")
{
  :ok,
  %DateTime{calendar: Calendar.ISO, day: 9, hour: 14, microsecond: {0, 0},
    minute: 52, month: 6, second: 34, std_offset: 0, time_zone: "Etc/UTC",
    utc_offset: 0, year: 2017, zone_abbr: "UTC"},
  <<166, 90, 80, 117, 89, 88, 196, 168, 113, 163, 157, 217, 224, 51, 151, 227>>
 }

defmodule EctoKsuid do
  @behaviour Ecto.Type
  # uses string/varchar as storage type.
  def type, do: :string

  def cast(ksuid) when is_binary(ksuid), do: {:ok, ksuid}
  def cast(_), do: :error

  @doc """
  Same as `cast/1` but raises `Ecto.CastError` on invalid arguments.
  """
  def cast!(value) do
    case cast(value) do
      {:ok, ksuid} -> ksuid
      :error -> raise Ecto.CastError, type: __MODULE__, value: value
    end
  end

  def load(ksuid), do: {:ok, ksuid}
  
  def dump(binary) when is_binary(binary), do: {:ok, binary}
  def dump(_), do: :error

  # Callback invoked by autogenerate fields - this is all that really matters
  # just passing around the binary otherwise.
  @doc false
  def autogenerate, do: Ksuid.generate()

end

defmodule TestSchema do
  use Ecto.Schema

  @primary_key {:id, EctoKsuid, autogenerate: true}
  schema "test" do
    field :name, :string
    field :inserted_at, :utc_datetime, virtual: true
  end

  def inserted_at(%TestSchema{id: ksuid} = row) do
     {:ok, time_stamp, _} = Ksuid.parse(ksuid)
     %TestSchema{row | inserted_at: time_stamp}
  end
  
end

  def change do
     create table(:test, primary_key: false) do
      add :id, :string, primary_key: true, size: 26
      add :name, :text
     
    end
  end

def deps do
  [{:ksuid, "~> 0.1.2"}]
end