Ruby/Rails: converting a Date to a UNIX timestamp
How would I get a UNIX timestamp (number of seconds since 1970 GMT) from a Date object in a Rails app?
I know Time#to_i returns a timestamp, but doing Date#to_time and then getting the timestamp results in something that's off by about a month (not sure why...).
Any help is appreciated, thanks!
Edit: OK, I think I figured it out- I was processing a date several times in a loop, and each time the date was moved a little because of a time zone mismatch, ultimately leading to my timestamp being a month off. Still, I'd be interested in knowing if there's any way to do this without relying on Date#to_time .
The code date.to_time.to_i should work fine. The Rails console session below shows an example:
>> Date.new(2009,11,26).to_time
=> Thu Nov 26 00:00:00 -0800 2009
>> Date.new(2009,11,26).to_time.to_i
=> 1259222400
>> Time.at(1259222400)
=> Thu Nov 26 00:00:00 -0800 2009
Note that the intermediate DateTime object is in local time, so the timestamp might be a several hours off from what you expect. If you want to work in UTC time, you can use the DateTime's method "to_utc".
I get the following when I try it:
>> Date.today.to_time.to_i
=> 1259244000
>> Time.now.to_i
=> 1259275709
The difference between these two numbers is due to the fact that Date does not store the hours, minutes or seconds of the current time. Converting a Date to a Time will result in that day, midnight.
当你有一个任意的DateTime对象时，用于Ruby 1.8的解决方案：
1.8.7-p374 :001 > require 'date'
=> true
1.8.7-p374 :002 > DateTime.new(2012, 1, 15).strftime('%s')
=> "1326585600"