Improve performance in various reports

app/controllers/spree/admin/reports_controller.rb

@@ -247,8 +247,10 @@ module Spree
       end
 
       def suppliers_of_products_distributed_by(distributors)
-        distributors.map { |d| Spree::Product.in_distributor(d).includes(:supplier).all }.
-          flatten.map(&:supplier).uniq
+        supplier_ids = Spree::Product.in_distributors(distributors).
+          select('spree_products.supplier_id')
+
+        Enterprise.where(id: supplier_ids)
       end
 
       # Load order cycles the current user has access to

app/models/spree/product_decorator.rb

@@ -84,6 +84,12 @@ Spree::Product.class_eval do
       select('distinct spree_products.*')
   }
 
+  scope :in_distributors, lambda { |distributors|
+    with_order_cycles_outer.
+      where('(o_exchanges.incoming = ? AND o_exchanges.receiver_id IN (?))', false, distributors).
+      uniq
+  }
+
   # Products supplied by a given enterprise or distributed via that enterprise through an OC
   scope :in_supplier_or_distributor, lambda { |enterprise|
     enterprise = enterprise.respond_to?(:id) ? enterprise.id : enterprise.to_i

spec/models/spree/product_spec.rb

@@ -257,6 +257,37 @@ module Spree
         end
       end
 
+      describe "in_distributors" do
+        let!(:distributor1) { create(:distributor_enterprise) }
+        let!(:distributor2) { create(:distributor_enterprise) }
+        let!(:product1) { create(:product) }
+        let!(:product2) { create(:product) }
+        let!(:product3) { create(:product) }
+        let!(:product4) { create(:product) }
+        let!(:order_cycle1) {
+          create(:order_cycle, distributors: [distributor1],
+                               variants: [product1.variants.first, product2.variants.first])
+        }
+        let!(:order_cycle2) {
+          create(:order_cycle, distributors: [distributor2],
+                               variants: [product3.variants.first])
+        }
+
+        it "returns distributed products for a given Enterprise AR relation" do
+          distributors_relation = Enterprise.where(id: [distributor1.id, distributor2.id])
+
+          expect(Product.in_distributors(distributors_relation)).to include product1, product2, product3
+          expect(Product.in_distributors(distributors_relation)).to_not include product4
+        end
+
+        it "returns distributed products for a given array of enterprise ids" do
+          distributors_ids = [distributor1.id, distributor2.id]
+
+          expect(Product.in_distributors(distributors_ids)).to include product1, product2, product3
+          expect(Product.in_distributors(distributors_ids)).to_not include product4
+        end
+      end
+
       describe "in_supplier_or_distributor" do
         it "shows products in supplier" do
           s1 = create(:supplier_enterprise)