Don't error when grouped calculations return 0 records

Fixes #18717

2 files changed, 6 insertions, 1 deletions

diff --git a/activerecord/lib/active_record/relation/calculations.rb b/activerecord/lib/active_record/relation/calculations.rb
index 83745bc169..c3c4d7f1ce 100644
--- a/activerecord/lib/active_record/relation/calculations.rb
+++ b/activerecord/lib/active_record/relation/calculations.rb
@@ -304,7 +304,7 @@ module ActiveRecord
 
       if association
         key_ids     = calculated_data.collect { |row| row[group_aliases.first] }
-        key_records = association.klass.base_class.find(key_ids)
+        key_records = association.klass.base_class.where(association.klass.base_class.primary_key => key_ids)
         key_records = Hash[key_records.map { |r| [r.id, r] }]
       end
 
diff --git a/activerecord/test/cases/calculations_test.rb b/activerecord/test/cases/calculations_test.rb
index 299217214e..f47568f2f5 100644
--- a/activerecord/test/cases/calculations_test.rb
+++ b/activerecord/test/cases/calculations_test.rb
@@ -631,4 +631,9 @@ class CalculationsTest < ActiveRecord::TestCase
 
     assert_equal({ "has trinket" => part.id }, ShipPart.joins(:trinkets).group("ship_parts.name").sum(:id))
   end
+
+  def test_calculation_grouped_by_association_doesnt_error_when_no_records_have_association
+    Client.update_all(client_of: nil)
+    assert_equal({ nil => Client.count }, Client.group(:firm).count)
+  end
 end