[wip] Generate variant unit options in Ruby

This re-implements Angular JS function VariantUnitManager.variantUnitOptions()

app/services/weights_and_measures.rb

@@ -1,6 +1,8 @@
 # frozen_string_literal: true
 
 class WeightsAndMeasures
+  include ActionView::Helpers::NumberHelper
+
   def initialize(variant)
     @variant = variant
     @units = UNITS
@@ -20,6 +22,28 @@ def system
     scales[product_scale.to_f]['system']
   end
 
+  # @returns enumerable with label and value for select
+  def self.variant_unit_options
+    self::UNITS.flat_map do |measurement, measurement_info|
+      measurement_info.filter_map do |scale, unit_info|
+        return unless self.available_units.include?(unit_info['name'])
+
+        # scale_clean = "%0.3g" % scale # 🆇 converts large numbers to scientific notation
+        # scale_clean = number_with_precision(scale, strip_insignificant_zeros: true) # why oh why won't the numbe rhelper work??
+        scale_clean = scale
+
+        [
+          "#{I18n.t(measurement)} (#{unit_info['name']})", # Label (eg "Weight (g)")
+          "#{measurement}_#{scale_clean}", # Scale ID (eg "weight_1")
+        ]
+      end
+    end <<
+      [
+        I18n.t('items'),
+        'items'
+      ]
+  end
+
   private
 
   UNITS = {
@@ -49,7 +73,7 @@ def scales_for_variant_unit(ignore_available_units: false)
     return @units[@variant.product.variant_unit] if ignore_available_units
 
     @units[@variant.product.variant_unit]&.reject { |_scale, unit_info|
-      available_units.exclude?(unit_info['name'])
+      self.available_units.exclude?(unit_info['name'])
     }
   end
 
@@ -68,7 +92,7 @@ def find_largest_unit(scales, product_scale_system)
     largest_unit
   end
 
-  def available_units
+  def self.available_units
     Spree::Config.available_units.split(",")
   end
 end

app/views/admin/products_v3/_product_row.html.haml

@@ -9,11 +9,14 @@
 %td.field
   = f.text_field :sku, 'aria-label': t('admin.products_page.columns.sku')
   = error_message_on product, :sku
-%td.align-right
-  .content
-    = product.variant_unit.upcase_first
-    / TODO: properly handle custom unit names
-    = WeightsAndMeasures::UNITS[product.variant_unit] && "(" + WeightsAndMeasures::UNITS[product.variant_unit][product.variant_unit_scale]["name"] + ")"
+%td.field
+  = product.variant_unit.upcase_first
+  / TODO: properly handle custom unit names
+  = WeightsAndMeasures::UNITS[product.variant_unit] && "(" + WeightsAndMeasures::UNITS[product.variant_unit][product.variant_unit_scale]["name"] + ")"
+  - if WeightsAndMeasures::UNITS[product.variant_unit]
+    = select_tag :variant_unit_with_scale, WeightsAndMeasures.variant_unit_options,
+      class: "fullwidth",
+      data: { "controller": "tom-select" }
 %td.align-right
   -# empty
 %td.align-right

spec/services/weights_and_measures_spec.rb

@@ -55,7 +55,51 @@
     end
   end
 
-  describe "#scale_for_unit_value" do
+  describe "#variant_unit_options" do
+    subject { WeightsAndMeasures.variant_unit_options }
+
+    it "returns options for each unit" do
+      expect(subject).to eq [
+        ["Weight (mg)", "weight_0.001"],
+        ["Weight (g)", "weight_1"],
+        ["Weight (oz)", "weight_28.35"],
+        ["Weight (lb)", "weight_453.6"],
+        ["Weight (kg)", "weight_1000"],
+        ["Weight (T)", "weight_1000000"],
+        ["Volume (mL)", "volume_0.001"],
+        ["Volume (cL)", "volume_0.01"],
+        ["Volume (dL)", "volume_0.1"],
+        ["Volume (L)", "volume_1"],
+        ["Volume (kL)", "volume_1000"],
+        ["Volume (gal)", "volume_4.54609"],
+        ["Items", "items"],
+      ]
+    end
+
+    describe "filtering available units" do
+      let(:available_units) { "g,kg,T,mL,L,kL,lb,oz" }
+
+      before do
+        allow(Spree::Config).to receive(:available_units).and_return(available_units)
+      end
+
+      it "returns options for available units only" do
+        expect(subject).to eq [
+          ["Weight (g)", "weight_1"],
+          ["Weight (oz)", "weight_28.35"],
+          ["Weight (lb)", "weight_453.6"],
+          ["Weight (kg)", "weight_1000"],
+          ["Weight (T)", "weight_1000000"],
+          ["Volume (mL)", "volume_0.001"],
+          ["Volume (L)", "volume_1"],
+          ["Volume (kL)", "volume_1000"],
+          ["Items", "items"],
+        ]
+      end
+    end
+  end
+
+  describe "#scales_for_unit_value" do
     context "weight" do
       before do
         allow(product).to receive(:variant_unit) { "weight" }