Introduce "suppliable" scope to represent any variant which can_supply?(1)

api/app/controllers/spree/api/variants_controller.rb

@@ -66,8 +66,13 @@ def scope
         end
 
         in_stock_only = ActiveRecord::Type::Boolean.new.cast(params[:in_stock_only])
+        suppliable_only = ActiveRecord::Type::Boolean.new.cast(params[:suppliable_only])
         variants = variants.accessible_by(current_ability, :read)
-        variants = variants.in_stock if in_stock_only || cannot?(:view_out_of_stock, Spree::Variant)
+        if in_stock_only || cannot?(:view_out_of_stock, Spree::Variant)
+          variants = variants.in_stock
+        elsif suppliable_only
+          variants = variants.suppliable
+        end
         variants
       end
 

api/spec/requests/spree/api/variants_controller_spec.rb

@@ -114,6 +114,32 @@ module Spree
           end
         end
 
+        context "only suplliable variants" do
+          subject { get spree.api_variants_path, params: { suppliable_only: "true" } }
+
+          context "variant is backorderable" do
+            before do
+              variant.stock_items.update_all(count_on_hand: 0, backorderable: true)
+            end
+
+            it "is not returned in the results" do
+              subject
+              expect(json_response["variants"].count).to eq 1
+            end
+          end
+
+          context "variant is unsuppliable" do
+            before do
+              variant.stock_items.update_all(count_on_hand: 0, backorderable: false)
+            end
+
+            it "is returned in the results" do
+              subject
+              expect(json_response["variants"].count).to eq 0
+            end
+          end
+        end
+
         context "all variants" do
           subject { get spree.api_variants_path, params: { in_stock_only: "false" } }
 

backend/app/assets/javascripts/spree/backend/orders/edit.js

@@ -1,6 +1,6 @@
 Spree.ready(function () {
   'use strict';
 
-  $('[data-hook="add_product_name"]').find('.variant_autocomplete').variantAutocomplete({ in_stock_only: true });
+  $('[data-hook="add_product_name"]').find('.variant_autocomplete').variantAutocomplete({ suppliable_only: true });
   $("[data-hook='admin_orders_index_search']").find(".variant_autocomplete").variantAutocomplete();
 });

backend/app/assets/javascripts/spree/backend/views/cart/line_item_row.js

@@ -84,6 +84,6 @@ Spree.Views.Cart.LineItemRow = Backbone.View.extend({
       noCancel: this.model.isNew() && this.model.collection.length == 1
     });
     this.$el.html(html);
-    this.$("[name=variant_id]").variantAutocomplete({ in_stock_only: true });
+    this.$("[name=variant_id]").variantAutocomplete({ suppliable_only: true });
   }
 });

core/app/models/spree/variant.rb

@@ -92,6 +92,8 @@ class Variant < Spree::Base
     # a parameter, the scope is limited to variants that are in stock in the
     # provided stock locations.
     #
+    # If you want to also include backorderable variants see {[suppliable}}
+    #
     # @param stock_locations [Array<Spree::StockLocation>] the stock locations to check
     # @return [ActiveRecord::Relation]
     def self.in_stock(stock_locations = nil)
@@ -103,6 +105,22 @@ def self.in_stock(stock_locations = nil)
       in_stock_variants
     end
 
+    # Returns a scope of Variants which are suppliable. This includes:
+    # * in_stock variants
+    # * backorderable variants
+    # * variants which do not track stock
+    #
+    # @return [ActiveRecord::Relation]
+    def self.suppliable
+      return all unless Spree::Config.track_inventory_levels
+      arel_conditions = [
+        arel_table[:track_inventory].eq(false),
+        Spree::StockItem.arel_table[:count_on_hand].gt(0),
+        Spree::StockItem.arel_table[:backorderable].eq(true)
+      ]
+      joins(:stock_items).where(arel_conditions.inject(:or))
+    end
+
     self.whitelisted_ransackable_associations = %w[option_values product prices default_price]
     self.whitelisted_ransackable_attributes = %w[weight sku]
 

core/spec/models/spree/variant_spec.rb

@@ -754,6 +754,40 @@
     end
   end
 
+  describe ".suppliable" do
+    subject { Spree::Variant.suppliable }
+    let!(:in_stock_variant) { create(:variant) }
+    let!(:out_of_stock_variant) { create(:variant) }
+    let!(:backordered_variant) { create(:variant) }
+    let!(:stock_location) { create(:stock_location) }
+
+    before do
+      in_stock_variant.stock_items.update_all(count_on_hand: 10)
+      backordered_variant.stock_items.update_all(count_on_hand: 0, backorderable: true)
+      out_of_stock_variant.stock_items.update_all(count_on_hand: 0, backorderable: false)
+    end
+
+    it "includes the in stock variant" do
+      expect( subject ).to include(in_stock_variant)
+    end
+
+    it "includes out of stock variant" do
+      expect( subject ).to include(backordered_variant)
+    end
+
+    it "does not include out of stock variant" do
+      expect( subject ).not_to include(out_of_stock_variant)
+    end
+
+    context "inventory levels globally not tracked" do
+      before { Spree::Config.track_inventory_levels = false }
+
+      it "includes all variants" do
+        expect( subject ).to include(in_stock_variant, backordered_variant, out_of_stock_variant)
+      end
+    end
+  end
+
   describe "#display_image" do
     subject { variant.display_image }