Seems that oracle not only allows ‘null’ dates, but also ‘empty’ dates. On ‘empty’ dates, the error would come up! I totally misjudged the results of the error then, it seems…
Below is what I changed in oracle_enhanced_oci_connection.rb in lib\ruby\gems\activerecord-oracle_enhanced-adapter-1.2.1\lib\connection_adapters\. The changed lines are marked with #MVR as comment above it. All I did is make ‘empty’ dates detectable and skip converting them to a date too, effectively making them ‘null’ values too 
Starts around line 128:
# ruby-oci8 1.0 returns OraDate
when OraDate
# MVR: treat 'empty' date/time strings as null too!
if !(v.hour == 0 && v.minute == 0 && v.second == 0 && v.year == 0 && v.month == 0 && v.day == 0)
# RSI: added emulate_dates_by_column_name functionality
if OracleEnhancedAdapter.emulate_dates && (v.hour == 0 && v.minute == 0 && v.second == 0)
v.to_date
else
# code from Time.time_with_datetime_fallback
begin
Time.send(Base.default_timezone, v.year, v.month, v.day, v.hour, v.minute, v.second)
rescue
offset = Base.default_timezone.to_sym == :local ? ::DateTime.local_offset : 0
::DateTime.civil(v.year, v.month, v.day, v.hour, v.minute, v.second, offset)
end
end
end
# ruby-oci8 2.0 returns Time or DateTime
when Time, DateTime
# MVR: treat 'empty' date/time strings as null too!
if !(v.hour == 0 && v.minute == 0 && v.second == 0 && v.year == 0 && v.month == 0 && v.day == 0)
if OracleEnhancedAdapter.emulate_dates && (v.hour == 0 && v.min == 0 && v.sec == 0)
v.to_date
else
# recreate Time or DateTime using Base.default_timezone
begin
Time.send(Base.default_timezone, v.year, v.month, v.day, v.hour, v.min, v.sec)
rescue
offset = Base.default_timezone.to_sym == :local ? ::DateTime.local_offset : 0
::DateTime.civil(v.year, v.month, v.day, v.hour, v.min, v.sec, offset)
end
end
end
else v
end
Hope this is of any help to those fighting with Oracle Cheers
Posted by rheenen 
