Remove N+1 in editable_variants_for_incoming_exchanges

app/serializers/api/admin/order_cycle_serializer.rb

@@ -33,14 +33,7 @@ class Api::Admin::OrderCycleSerializer < ActiveModel::Serializer
   end
 
   def editable_variants_for_incoming_exchanges
-    # For each enterprise that the current user is able to see in this order cycle,
-    # work out which variants should be editable within incoming exchanges from that enterprise
-    editable = {}
-    visible_enterprises.each do |enterprise|
-      variants = permissions.editable_variants_for_incoming_exchanges_from(enterprise).pluck(:id)
-      editable[enterprise.id] = variants if variants.any?
-    end
-    editable
+    sort_by_supplier_id(permissions.all_incoming_editable_variants.all)
   end
 
   def editable_variants_for_outgoing_exchanges
@@ -85,4 +78,18 @@ class Api::Admin::OrderCycleSerializer < ActiveModel::Serializer
   def visible_enterprises
     @visible_enterprises ||= permissions.visible_enterprises
   end
+
+  def sort_by_supplier_id(variants)
+    collection = {}
+    variants.map do |variant|
+      supplier_id = variant.product.supplier_id
+
+      if collection.key? supplier_id
+        collection[supplier_id] << variant.id
+      else
+        collection[supplier_id] = [variant.id]
+      end
+    end
+    collection
+  end
 end

lib/open_food_network/order_cycle_permissions.rb

@@ -154,6 +154,15 @@ module OpenFoodNetwork
       end
     end
 
+    def all_incoming_editable_variants
+      valid_suppliers = visible_enterprises.map do |enterprise|
+        enterprise.id if user_manages_coordinator_or(enterprise)
+      end
+
+      Spree::Variant.includes(product: :supplier).
+        joins(:product).where('spree_products.supplier_id IN (?)', valid_suppliers)
+    end
+
     # Find the variants that a user is permitted see within outgoing exchanges
     # Note that this does not determine whether they actually appear in outgoing exchanges
     # as this requires first that the variant is included in an incoming exchange