Import DFC SuppliedProduct as new variant of existing product

app/models/spree/product.rb

@@ -272,18 +272,6 @@ def destruction
       end
     end
 
-    private
-
-    def update_units
-      return unless saved_change_to_variant_unit? || saved_change_to_variant_unit_name?
-
-      variants.each(&:update_units)
-    end
-
-    def touch_distributors
-      Enterprise.distributing_products(id).each(&:touch)
-    end
-
     def ensure_standard_variant
       return unless variants.empty?
 
@@ -298,6 +286,18 @@ def ensure_standard_variant
       variants << variant
     end
 
+    private
+
+    def update_units
+      return unless saved_change_to_variant_unit? || saved_change_to_variant_unit_name?
+
+      variants.each(&:update_units)
+    end
+
+    def touch_distributors
+      Enterprise.distributing_products(id).each(&:touch)
+    end
+
     def validate_image
       return if image.blank? || image.valid?
 

engines/dfc_provider/app/controllers/dfc_provider/supplied_products_controller.rb

@@ -14,13 +14,19 @@ def create
 
       return head :bad_request unless supplied_product
 
-      product = SuppliedProductBuilder.import(supplied_product)
-      product.supplier = current_enterprise
-      product.save!
+      variant = SuppliedProductBuilder.import_variant(supplied_product)
+      product = variant.product
 
-      supplied_product = SuppliedProductBuilder.supplied_product(
-        product.variants.first
-      )
+      if product.new_record?
+        product.supplier = current_enterprise
+        product.save!
+      end
+
+      if variant.new_record?
+        variant.save!
+      end
+
+      supplied_product = SuppliedProductBuilder.supplied_product(variant)
       render json: DfcIo.export(supplied_product)
     end
 

engines/dfc_provider/app/services/supplied_product_builder.rb

@@ -17,7 +17,25 @@ def self.supplied_product(variant)
     )
   end
 
-  def self.import(supplied_product)
+  def self.import_variant(supplied_product)
+    product_id = supplied_product.spree_product_id
+
+    if product_id.present?
+      product = Spree::Product.find(product_id)
+      Spree::Variant.new(
+        product: product,
+        price: 0,
+      ).tap do |variant|
+        apply(supplied_product, variant)
+      end
+    else
+      product = import_product(supplied_product)
+      product.ensure_standard_variant
+      product.variants.first
+    end
+  end
+
+  def self.import_product(supplied_product)
     Spree::Product.new(
       name: supplied_product.name,
       description: supplied_product.description,

engines/dfc_provider/lib/data_food_consortium/connector/importer.rb

@@ -127,11 +127,15 @@ def skos_concept(object)
       end
 
       def guess_setter_name(predicate)
-        fragment = predicate.fragment
+        name =
+
+          # Some predicates are named like `hasQuantity`
+          # but the attribute name would be `quantity`.
+          predicate.fragment&.sub(/^has/, "")&.camelize(:lower) ||
+
+          # And sometimes the URI looks like `ofn:spree_product_id`.
+          predicate.to_s.split(":").last
 
-        # Some predicates are named like `hasQuantity`
-        # but the attribute name would be `quantity`.
-        name = fragment.sub(/^has/, "").camelize(:lower)
 
         "#{name}="
       end

engines/dfc_provider/spec/requests/supplied_products_spec.rb

@@ -96,6 +96,27 @@
           expect(variant.unit_value).to eq 3
           expect(variant.product_id).to eq spree_product_id
 
+          # References the associated Spree::Product
+          product_id = json_response["ofn:spree_product_id"]
+          product = Spree::Product.find(product_id)
+          expect(product.name).to eq "Apple"
+          expect(product.variants).to eq [variant]
+
+          # Creates a variant for existing product
+          supplied_product[:"ofn:spree_product_id"] = product_id
+          supplied_product[:"dfc-b:hasQuantity"][:"dfc-b:value"] = 6
+
+          expect {
+            submit_request(example.metadata)
+            product.variants.reload
+          }
+            .to change { product.variants.count }.by(1)
+
+          variant_id = json_response["@id"].split("/").last.to_i
+          second_variant = Spree::Variant.find(variant_id)
+          expect(product.variants).to match_array [variant, second_variant]
+          expect(second_variant.unit_value).to eq 6
+
           # Insert static value to keep documentation deterministic:
           response.body.gsub!(
             "supplied_products/#{variant_id}",