Normalize date component when writing to time columns

For legacy reasons Rails stores time columns on sqlite as full
timestamp strings. However because the date component wasn't being
normalized this meant that when they were read back they were being
prefixed with 2001-01-01 by ActiveModel::Type::Time. This had a
twofold result - first it meant that the fast code path wasn't being
used because the string was invalid and second it was corrupting the
second fractional component being read by the Date._parse code path.

Fix this by a combination of normalizing the timestamps on writing
and also changing Active Model to be more lenient when detecting
whether a string starts with a date component before creating the
dummy time value for parsing.

1 files changed, 1 insertions, 5 deletions

diff --git a/activemodel/lib/active_model/type/time.rb b/activemodel/lib/active_model/type/time.rb
index 8e939ac00a..c094ee0013 100644
--- a/activemodel/lib/active_model/type/time.rb
+++ b/activemodel/lib/active_model/type/time.rb
@@ -31,11 +31,7 @@ module ActiveModel
           return apply_seconds_precision(value) unless value.is_a?(::String)
           return if value.empty?
 
-          if value.start_with?("2000-01-01")
-            dummy_time_value = value
-          else
-            dummy_time_value = "2000-01-01 #{value}"
-          end
+          dummy_time_value = value.sub(/\A(\d\d\d\d-\d\d-\d\d |)/, "2000-01-01 ")
 
           fast_string_to_time(dummy_time_value) || begin
             time_hash = ::Date._parse(dummy_time_value)