Problems with saving and querying dates in Rails

I have an Appointment model, and for one particular appointment, I saved it having a start_time of 12:15am on 3/5/2011. Look at this:

irb(main):002:0> a = Appointment.find(15)
=> #<Appointment id: 15, start_time: "2011-03-05 05:15:00", created_at: "2011-03-05 03:42:03", updated_at: "2011-03-05 03:42:03", stylist_id: 13, client_id: 8>
irb(main):003:0> a.start_time
=> Sat, 05 Mar 2011 00:15:00 EST -05:00

As 开发者_运维技巧you can see, the date got saved wrong. Interestingly, though, Rails compensates for it when the data comes back out.

I assume my app has always behaved this way and I just didn't notice. Recently, though, I wrote a query that pulls the dates out with raw SQL, so I'm getting the wrong time and it's causing problems.

Can anyone shed some light on why this is happening and what I can do to get around the problem?

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Rails does this on purpose. Check your time zone settings:

• config.active_record.default_timezone
• config.time_zone

http://guides.rubyonrails.org/configuring.html#configuring-active-record

Time zone features were introduced in 2.1 and haven't changed much. This article gives a good explanation: http://mad.ly/2008/04/09/rails-21-time-zone-support-an-overview/

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Rails save datetime in database in UTC time(zero offset) and converts the time to the time zone which we intend when it displays it. So, when we parse directly from the database, you will be getting UTC time. If you try to convert it into time like this:

time_string = #raw string obtained from database(like "2011-03-05 05:15:00")
time_object = Time.parse(time_string)

You will get the time with offset according to the timezone of your machine or server. Ruby parses time like that. It will take the time and give the timezone of your machine(which is incorrect here as the timezone is actually UTC as it is from database). I ran into this problem and solved it by adding UTC when I parse time from raw sql strings from database.

time_string << " UTC" 
time_object = Time.parse(time_string) # gives time zone as UTC

then if you use it, the result will be correct.