I’m building a new module for my multi-tenant application and trying to come to terms how a prefix ideally be passed in. Here is a new style using an opts keyword list with a required prefix value. I like this since I could also use a preloads option for get style functions letting the caller decide which relationships should be preloaded; I think this preload style will come in handy for my GraphQL stuff. Anyways would love some API design feedback on this draft:

defmodule Guildflow.Invites do
  @moduledoc """
  Provides functions for creating invites that will be shared with prospective
  members. Using an invite a `Member` account can be created.
  """

  alias Guildflow.Invites.{Invite}
  alias Guildflow.Repo

  @expiration_length_in_seconds 60 * 60 * 24 * 7

  @doc """
  Generates and stores a fresh invite.
  ## Options
    * `:prefix` - The database prefix to use for the insert. (required)
    * `:preloads` - a list of relationships that will be preloaded on the
      returned records. (demo of an option that would be on a get style
      function)
  """
  @spec create_invite(keyword) :: {:ok, Ecto.Schema.t()} | {:error, Ecto.Changeset.t()}
  def create_invite(opts \\ []) do
    expires_on =
      DateTime.utc_now()
      |> DateTime.add(@expiration_length_in_seconds, :second)
      |> DateTime.truncate(:second)

    changeset =
      Invite.changeset(%Invite{}, %{
        "token" => UUID.uuid4(),
        "expires_on" => expires_on
      })

    Repo.insert(changeset, prefix: prefix_from_options(opts))
  end

  def register_member_from_invite(_invite) do
  end

  defp prefix_from_options(opts) do
    case Keyword.get(opts, :prefix, []) do
      nil ->
        throw("required prefix missing")

      prefix ->
        prefix
    end
  end
end