Explicitly retrieve data after pagination

The idea here is to make it explicit that at this point we are handling
an array and not a relation anymore.

lib/api/helpers/pagination.rb

@@ -6,6 +6,12 @@ module API
       def paginate(relation)
         ::Gitlab::Pagination::OffsetPagination.new(self).paginate(relation)
       end
+
+      # This applies pagination and executes the query
+      # It always returns an array instead of an ActiveRecord relation
+      def paginate_and_retrieve!(relation)
+        paginate(relation).to_a
+      end
     end
   end
 end

lib/api/projects.rb

@@ -84,7 +84,6 @@ module API
       def prepare_query(projects)
         projects = reorder_projects(projects)
         projects = apply_filters(projects)
-        projects = paginate(projects)
 
         projects, options = with_custom_attributes(projects)
 
@@ -105,6 +104,8 @@ module API
       def prepare_and_present(project_relation)
         projects, options = prepare_query(project_relation)
 
+        projects = paginate_and_retrieve!(projects)
+
         # Refresh count caches
         options[:with].execute_batch_counting(projects)
 

spec/lib/api/helpers/pagination_spec.rb

@@ -19,4 +19,18 @@ describe API::Helpers::Pagination do
       expect(result).to eq(expected_result)
     end
   end
+
+  describe '#paginate_and_retrieve!' do
+    let(:relation) { double("relation") }
+
+    let(:paginated_result) { double }
+    let(:result) { double }
+
+    it 'applies pagination and returns an array' do
+      expect(subject).to receive(:paginate).with(relation).and_return(paginated_result)
+      expect(paginated_result).to receive(:to_a).and_return(result)
+
+      expect(subject.paginate_and_retrieve!(relation)).to eq(result)
+    end
+  end
 end