Friday, May 1, 2009

Saving Dates to Oracle with JRuby / Rails

When you create date or datetime attributes in rails, both types get mapped to date columns in Oracle. The problem I was running into was trying to save date values (without time values).

Date attributes that were set in a view worked fine, but those that were set programmatically were getting saved with the time -- the time being offset from midnight based upon my timezone. I messed with the timezone setting ("config.timezone =" in environment.rb), but everything seemed to be working fine except this. It works if you set the attribute to a string value (i.e., '2009-05-01'), like the view / controller code does, but that's a pain.

So, digging through the activerecord extensions in jdbc_oracle.rb, I found that it tries to guess the type based upon whether there are values for hours, minutes, or seconds in the ActiveSupport::TimeWithZone objects that get sent through. The ones coming from the view had no hours, minutes, nor seconds, but the ones that had been set in the code (originally set to, for example) were getting converted into TimeWithZone objects that were midnight on the specified date, then adjusted for the timezone, turning the date part into the prior date. (I didn't dig through the rails code to find out where/how/why that conversion is taking place, but that might yield a better solution -- if any body knows, please share!) Since rails uses TimeWithZone objects, that seemed like a reasonable place to look.

Looking at the doc for TimeWithZone, it says that you shouldn't ever create instances directly, you should use TimeZone methods instead, via the instance. The TimeZone methods include "today", "local", "parse" etc -- nice! So I tried each of those:
  • a =
  • b =, 5, 1)
  • c ='2009-05-01')
Well, "b" and "c" worked -- they got saved to the database as dates -- but "a" acted the same as It turns out that's exactly what returns: a Date instance!?! I'm not sure why it works that way, but...

So, until I have time to dig through rails to see if there's a way to avoid the time zone conversion (besides setting the attribute to a string), I'll start using the TimeZone methods, with this little patch stuck in the config/initializers/ directory:

class ActiveSupport::TimeZone
def today
today =
self.local(today.year, today.month,

Again, if anyone has another suggestion, please share. Also, I'm not sure if this is JRuby-specific, but I don't have time to test that right now either...

(Note: running rails 2.2.2 w/ jruby 1.1.5 and activerecord-jdbc-adapter 0.9)

1 comment:

  1. Use Oracle enhanced adapter instead of JDBC adapter and then use set_date_columns to specify which columns should store date without time (see