Merge pull request #20317

AR: take precision into count when assigning a value to timestamp
attribute

2 files changed, 12 insertions, 9 deletions

diff --git a/activemodel/lib/active_model/type/date_time.rb b/activemodel/lib/active_model/type/date_time.rb
index b068cfc672..2f2df4320f 100644
--- a/activemodel/lib/active_model/type/date_time.rb
+++ b/activemodel/lib/active_model/type/date_time.rb
@@ -12,11 +12,11 @@ module ActiveModel
 
       private
 
-      def cast_value(string)
-        return string unless string.is_a?(::String)
-        return if string.empty?
+      def cast_value(value)
+        return apply_seconds_precision(value) unless value.is_a?(::String)
+        return if value.empty?
 
-        fast_string_to_time(string) || fallback_string_to_time(string)
+        fast_string_to_time(value) || fallback_string_to_time(value)
       end
 
       # '0.123456' -> 123456
diff --git a/activemodel/lib/active_model/type/helpers/time_value.rb b/activemodel/lib/active_model/type/helpers/time_value.rb
index 0a0e58654b..63993c0d93 100644
--- a/activemodel/lib/active_model/type/helpers/time_value.rb
+++ b/activemodel/lib/active_model/type/helpers/time_value.rb
@@ -5,11 +5,7 @@ module ActiveModel
     module Helpers
       module TimeValue # :nodoc:
         def serialize(value)
-          if precision && value.respond_to?(:usec)
-            number_of_insignificant_digits = 6 - precision
-            round_power = 10 ** number_of_insignificant_digits
-            value = value.change(usec: value.usec / round_power * round_power)
-          end
+          value = apply_seconds_precision(value)
 
           if value.acts_like?(:time)
             zone_conversion_method = is_utc? ? :getutc : :getlocal
@@ -34,6 +30,13 @@ module ActiveModel
           end
         end
 
+        def apply_seconds_precision(value)
+          return value unless precision && value.respond_to?(:usec)
+          number_of_insignificant_digits = 6 - precision
+          round_power = 10 ** number_of_insignificant_digits
+          value.change(usec: value.usec / round_power * round_power)
+        end
+
         def type_cast_for_schema(value)
           "'#{value.to_s(:db)}'"
         end