Honor currency's fractional digits (again)

CHANGELOG.md

@@ -1,5 +1,13 @@
 # Changelog
 
+## Cldr Numbers v2.32.1
+
+This is the changelog for Cldr v2.32.0 released on September 9th, 2023.  For older changelogs please consult the release tag on [GitHub](https://github.com/elixir-cldr/cldr_numbers/tags)
+
+### Bug Fixes
+
+* Use currency default fractional digits for currency formats if no `:fractional_digits` option is provided. Thanks to @dhedlund  for the report.  This reverts that change made in 2.31.3 which was described as "Don't override currency fractional digits when formatting a number. The format should always define the fractional digits unless overriden by the `:fractional_digits` option." Fractional digits will also be set to the currency definition of digits unless overriden.
+
 ## Cldr Numbers v2.32.0
 
 This is the changelog for Cldr v2.32.0 released on September 4th, 2023.  For older changelogs please consult the release tag on [GitHub](https://github.com/elixir-cldr/cldr_numbers/tags)

lib/cldr/number/format/options.ex

@@ -126,7 +126,7 @@ defmodule Cldr.Number.Format.Options do
       options
       |> validate_each_option(backend)
       |> confirm_currency_format_has_currency()
-      |> maybe_adjust_currency_format(options.currency, options.format)
+      |> maybe_adjust_currency_format(options.currency, options.format, backend)
       |> resolve_standard_format(backend)
       |> maybe_expand_currency_symbol(number)
       |> maybe_apply_alpha_next_to_number(backend)
@@ -172,24 +172,61 @@ defmodule Cldr.Number.Format.Options do
   # :narrow, the format to :currency
 
   @doc false
-  defp maybe_adjust_currency_format(options, currency, :narrow) when not is_nil(currency) do
+  defp maybe_adjust_currency_format(options, currency, :narrow, backend) when not is_nil(currency) do
     currency_format = derive_currency_format(options)
 
     options
     |> Map.put(:currency_symbol, :narrow)
     |> Map.put(:format, currency_format)
     |> Map.put(:currency_format, currency_format)
+    |> set_default_fractional_digits(backend)
   end
 
   # We keep a record of whether the currency format is :currency or :accounting
   # because later on we may need to adjust the "alpha_next_to_number" format
 
-  defp maybe_adjust_currency_format(%{format: format} = options, currency, _)
+  defp maybe_adjust_currency_format(%{format: format} = options, currency, _format, backend)
        when not is_nil(currency) and format in [:accounting, :currency] do
-    Map.put(options, :currency_format, options.format)
+    options
+    |> Map.put(:currency_format, options.format)
+    |> set_default_fractional_digits(backend)
+  end
+
+  defp maybe_adjust_currency_format(options, _currency, _format, _backend) do
+    options
+  end
+
+  defp set_default_fractional_digits(%{fractional_digits: nil, currency_digits: :accounting} = options, backend) do
+    case Cldr.Currency.currency_for_code(options.currency, backend, locale: options.locale) do
+      {:ok, currency} ->
+        Map.put(options, :fractional_digits, currency.digits)
+
+      _other ->
+        options
+     end
+  end
+
+  defp set_default_fractional_digits(%{fractional_digits: nil, currency_digits: :cash} = options, backend) do
+    case Cldr.Currency.currency_for_code(options.currency, backend, locale: options.locale) do
+      {:ok, currency} ->
+        Map.put(options, :fractional_digits, currency.cash_digits)
+
+      _other ->
+        options
+     end
+  end
+
+  defp set_default_fractional_digits(%{fractional_digits: nil, currency_digits: :iso} = options, backend) do
+    case Cldr.Currency.currency_for_code(options.currency, backend, locale: options.locale) do
+      {:ok, currency} ->
+        Map.put(options, :fractional_digits, currency.iso_digits)
+
+      _other ->
+        options
+     end
   end
 
-  defp maybe_adjust_currency_format(options, _currency, _format) do
+  defp set_default_fractional_digits(options, _backend) do
     options
   end
 
@@ -388,7 +425,7 @@ defmodule Cldr.Number.Format.Options do
     System.system_name_from(number_system, locale, backend)
   end
 
-  # Currency validation returns a t: Cldr.Currency.t/0
+  # Currency validation returns a t:Cldr.Currency.t/0
 
   defp validate_option(:currency, %{locale: locale}, backend, :from_locale) do
     currency_from_locale(locale, backend)

mix.exs

@@ -3,7 +3,7 @@ defmodule Cldr.Numbers.Mixfile do
 
   use Mix.Project
 
-  @version "2.32.0"
+  @version "2.32.1"
 
   def project do
     [

test/support/number_format_test_data.exs

@@ -56,6 +56,10 @@ defmodule Cldr.Test.Number.Format do
       {1234, "COP 1,234.00", [currency: :COP, currency_digits: :iso]},
       {1234, "COP 1,234.00", [currency: :COP]},
 
+      # Currency default fractional digits
+      {1234, "¥1,234", [currency: :JPY]},
+      {1234, "TND 1,234.000", [currency: :TND]},
+
       # Currency with varying currency symbol
       {1234, "CUSTOM 1,234.00", [currency: :AUD, currency_symbol: "CUSTOM"]},
       {1234, "$1,234.00", [currency: :AUD, currency_symbol: :narrow]},