Question

In Ruby I am trying to convert a Date into a format that is usable by the HighCharts JavaScript charting library. Odd thing is when I convert the Date to seconds it converts differently than when I convert a Time to seconds and differently when I convert a DateTime to seconds. Due to this difference in conversion the dates displayed on the Graph can be as much as 1 date behind.

I am sure this has something to do with Rails and how it handles conversion from UTC to Local. If someone could explain to me the details I would greatly appreciate it.

In my examples below I use the same date ‘2011/05/02’ but the seconds come out to be different.

Examples:

Date.new(2011, 5, 2).to_time.to_i * 1000
=> 1304265600000
=> 05/01/2011

Time.utc(2011, 5, 2).to_i * 1000
=> 1304294400000
=> 05/02/2011

Date.new(2011, 5, 2).to_datetime.to_i * 1000
=> 1304294400000
=> 05/02/2011

Answer 1

ruby-1.9.2-p180 :106 > Time.utc(2011, 5, 2)
=> 2011-05-02 00:00:00 UTC 
ruby-1.9.2-p180 :107 > Date.new(2011, 5, 2).to_time
=> 2011-05-02 00:00:00 +0300

Date.to_time generates Time with timezone. That’s your difference.
The quick fix/hack that popped instantly into my mind is:

Date.new(2011, 5, 2).to_time.utc.midnight

Edit:
http://apidock.com/rails/Date/to_time

Date.new(2011, 5, 2).to_time(:utc)