Remove the selects when counting the last page

The last page of the first collection is only loaded into memory when
it is being viewed. If it isn't loaded into memory, the `#size` call
triggers a count query.

This `#count` would generate an invalid query if our custom preloaded
counts are included by adding a separate `as count_column` alias on
top of the count aliases. Removing the selects in this case will make
sure a valid `COUNT(*)` is generated.

1 files changed, 11 insertions, 0 deletions

diff --git a/spec/controllers/groups/children_controller_spec.rb b/spec/controllers/groups/children_controller_spec.rb
index 4262d474e59..cb1b460fc0e 100644
--- a/spec/controllers/groups/children_controller_spec.rb
+++ b/spec/controllers/groups/children_controller_spec.rb
@@ -280,6 +280,17 @@ describe Groups::ChildrenController do
 
           expect(assigns(:children)).to contain_exactly(other_subgroup, *next_page_projects.take(per_page - 1))
         end
+
+        context 'with a mixed first page' do
+          let!(:first_page_subgroups) { [create(:group,  :public,  parent: group)] }
+          let!(:first_page_projects) { create_list(:project, per_page, :public, namespace: group) }
+
+          it 'correctly calculates the counts' do
+            get :index, group_id: group.to_param, sort: 'id_asc', page: 2, format: :json
+
+            expect(response).to have_gitlab_http_status(200)
+          end
+        end
       end
     end
   end