Merge pull request #18850 from kamipo/fix_rounding_problem_for_postgresql_timestamp_column

Fix rounding problem for PostgreSQL timestamp column

2 files changed, 13 insertions, 12 deletions

diff --git a/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb b/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
index 1ce5f5ae58..c29692d6ca 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
@@ -917,18 +917,10 @@ module ActiveRecord
       end
 
       class MysqlDateTime < Type::DateTime # :nodoc:
-        def type_cast_for_database(value)
-          if value.acts_like?(:time) && value.respond_to?(:usec)
-            result = super.to_s(:db)
-            case precision
-            when 1..6
-              "#{result}.#{sprintf("%0#{precision}d", value.usec / 10 ** (6 - precision))}"
-            else
-              result
-            end
-          else
-            super
-          end
+        private
+
+        def has_precision?
+          precision || 0
         end
       end
 
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/oid/date_time.rb b/activerecord/lib/active_record/connection_adapters/postgresql/oid/date_time.rb
index b9e7894e5c..2fe61eeb77 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/oid/date_time.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/oid/date_time.rb
@@ -5,6 +5,15 @@ module ActiveRecord
         class DateTime < Type::DateTime # :nodoc:
           include Infinity
 
+          def type_cast_for_database(value)
+            if has_precision? && value.acts_like?(:time) && value.year <= 0
+              bce_year = format("%04d", -value.year + 1)
+              super.sub(/^-?\d+/, bce_year) + " BC"
+            else
+              super
+            end
+          end
+
           def cast_value(value)
             if value.is_a?(::String)
               case value