Fl4m3Ph03n1x

How to convert a typed definition to a typedstruct?

Background

I am moving towards defined data structures in my application, and I find that TypedStruct is quite useful.

Questions

However, I have recently found a little hickup. I don’t know how to convert this definition into a typedstruct:

  @type order_info :: %{
    (visible :: String.t()) => boolean,
    (order_type :: String.t()) => String.t(),
    (platform :: String.t()) => String.t(),
    (platinum :: String.t()) => non_neg_integer,
    (user :: String.t()) => %{
      (ingame_name :: String.t()) => String.t(),
      (status :: String.t()) => String.t()
    }
  }

My main issue here is the user map. Aside from the fact I don’t know how to define a typedstruct inside a trypedstruct, how do you folks do this?

Do you simply define a map inside the order_info typedstruct and ignore the mandatory parameters for the user map?
Do you create another typedstruct (called user) that goes inside the typedsctruct called order_info?
What is the standard option in Elixir ?

1 comment

/elixir #types

3 890 1

2023-01-26 09:05:05 UTC

Marked As Solved

Fl4m3Ph03n1x

Answer

After talking with other folks at the community I have opted for separating the User into a struct, in its own module, inside an OrderInfo directory:

lib/
  order_info/
    user.ex
  order_info.ex

I personally find this works great for readability. So for readability purposes this is what I ended up with:

defmodule AuctionHouse.Data.OrderInfo.User do
  @moduledoc """
  Represents the account information for a User.
  """

  use TypedStruct

  alias AuctionHouse.Shared.Utils

  @type user :: %{
          (ingame_name :: String.t()) => String.t(),
          (status :: String.t()) => String.t()
        }

  typedstruct enforce: true do
    @typedoc "Account information of an User"

    field(:ingame_name, String.t())
    field(:status, String.t())
  end

  @spec new(user) :: __MODULE__.t()
  def new(
        %{
          "ingame_name" => ingame_name,
          "status" => status
        } = user
      )
      when is_binary(ingame_name) and is_binary(status),
      do: Utils.string_map_to_struct(user, __MODULE__)
end

An then OrderInfo is basically the same, as seen by this typedstruct definition:

  typedstruct enforce: true do
    @typedoc "Information about an order"

    field(:visible, boolean())
    field(:order_type, String.t())
    field(:platform, String.t())
    field(:platinum, non_neg_integer())
    field(:user, __MODULE__.User.t())
  end

Extra

One thing to mention here, is that struct will not convert string maps to structures, only atom maps. So in order to achieve my goal of converting string maps to structures, I created this little helper function:

defmodule AuctionHouse.Shared.Utils do
  @moduledoc """
  Set of functions used across the app, for utility purposes, like dealing with
  tuples, maps and other data structures.
  """

  alias Morphix

  @spec string_map_to_struct(data :: map, target_struct :: module | struct) ::
          target_struct :: struct
  def string_map_to_struct(data, target_struct) do
    data
    |> Morphix.atomorphiform!()
    |> data_to_struct(target_struct)
  end

  @spec data_to_struct(data :: Enumerable.t(), target_struct :: module | struct) ::
          target_struct :: struct
  def data_to_struct(data, target_struct), do: struct(target_struct, data)
end

Here I used Morphix to do the hard work, but this can also be achieved by other means, see: