Eagerly de-duplicating items when submitting request

app/services/partners/request_create_service.rb

@@ -54,16 +54,27 @@ def populate_item_request(partner_request)
         attrs['item_id'].blank? && attrs['quantity'].blank?
       end
 
-      item_requests = formatted_line_items.map do |ira|
-        Partners::ItemRequest.new(
-          item_id: ira['item_id'],
-          quantity: ira['quantity'],
-          children: ira['children'] || [], # will create ChildItemRequests if there are any
-          name: fetch_organization_item_name(ira['item_id']),
-          partner_key: fetch_organization_partner_key(ira['item_id'])
-        )
+      items = {}
+
+      formatted_line_items.each do |input_item|
+        pre_existing_entry = items[input_item['item_id']]
+        if pre_existing_entry
+          pre_existing_entry.quantity = (pre_existing_entry.quantity.to_i + input_item['quantity'].to_i).to_s
+          # TODO: Is the following the correct way to merge?
+          pre_existing_entry.children += (input_item['children'] || [])
+        else
+          items[input_item['item_id']] = Partners::ItemRequest.new(
+            item_id: input_item['item_id'],
+            quantity: input_item['quantity'],
+            children: input_item['children'] || [], # will create ChildItemRequests if there are any
+            name: fetch_organization_item_name(input_item['item_id']),
+            partner_key: fetch_organization_partner_key(input_item['item_id'])
+          )
+        end
       end
 
+      item_requests = items.values
+
       partner_request.item_requests << item_requests
 
       partner_request.request_items = partner_request.item_requests.map do |ir|

spec/services/partners/request_create_service_spec.rb

@@ -86,6 +86,41 @@
         expect(NotifyPartnerJob).to have_received(:perform_now).with(Request.last.id)
       end
 
+      it 'should have created item requests' do
+        subject
+        expect(Partners::ItemRequest.count).to eq(item_requests_attributes.count)
+      end
+
+      context 'when we have duplicate item as part of request' do
+        let(:duplicate_item) { FactoryBot.create(:item) }
+        let(:unique_item) { FactoryBot.create(:item) }
+        let(:item_requests_attributes) do
+          [
+            ActionController::Parameters.new(
+              item_id: duplicate_item.id,
+              quantity: 3
+            ),
+            ActionController::Parameters.new(
+              item_id: unique_item.id,
+              quantity: 7
+            ),
+            ActionController::Parameters.new(
+              item_id: duplicate_item.id,
+              quantity: 5
+            )
+          ]
+        end
+        it 'should add the quantity of the duplicate item' do
+          subject
+          aggregate_failures {
+            expect(Partners::ItemRequest.count).to eq(2)
+            expect(Partners::ItemRequest.find_by(item_id: duplicate_item.id).quantity).to eq("8")
+            expect(Partners::ItemRequest.find_by(item_id: unique_item.id).quantity).to eq("7")
+            expect(Partners::ItemRequest.first.item_id).to eq(duplicate_item.id)
+          }
+        end
+      end
+
       context 'but a unexpected error occured during the save' do
         let(:error_message) { 'boom' }