CODEWITHSUNDEEP
ruby-on-railsruby-on-rails-4
willfore
willfore

Reputation: 170

Daylight Savings Time ignored using in_time_zone Rails 4

I'm having a frustrating issue that I can't seem to narrow down. I have searched many similar articles but they are not close enough to my issue to resolve. I am trying to pull a time from the database and display it in more than one time zone. My Rails app is using UTC as default. Here is what I'm doing:

On the create action I take the string of time which will be saved in the time column in my DB:

params[:schedule][:start] = "09:00"
Time.zone = "Central Time (US & Canada)"
@schedule.start = Time.zone.parse(params[:schedule][:start])

The above formats the time as it is supposed to:

2016-04-12 09:00:00 -0500

This is saved in the DB as:

2000-01-01 14:00:00

This has no time offset which is fine since I know it's in UTC. The problem happens when I go to display the time:

@schedule.start.in_time_zone("Central Time (US & Canada)")

This returns:

Sat, 01 Jan 2000 08:00:00 CST -06:00

Now, since this is a time column, I don't care about the date. I plan on formatting the value to only show the time. However, it is showing CST when it is currently CDT.

I can't figure out why this is happening. As I said I am not setting the Time Zone anywhere in my application.rb or anywhere else and I only set the Time zone on the create action which should be fine when moving to a new action.

Any help on clarifying this would be awesome!

This seems to be because when the time is stored it is stored with the date in the year 2000-01-01 which seems to be why it is using CST. How can I ignore the date when converting it to a particular timezone or will I need to change the column type to DateTime to get this to work properly?

Upvotes: 2

Views: 485

Answers (2)

PJSCopeland
PJSCopeland

Reputation: 3016

The fact that it matters whether it's CST or CDT means you do, on some level, care about the date. While I'm not familiar with the exact rules of Daylight Savings in that region, I do know that Jan 1 is the middle of winter and will definitely not be on Daylight Savings time.

Add the relevant date into your @schedule before putting it into a time zone, and it should fix the problem.

Upvotes: 0

Matouš Borák
Matouš Borák

Reputation: 15954

It is showing CST simply because the time is read from the database including the stored date, i.e. it's read as 09:00 of Jan 1st 2000.

I guess you'd have to parse the time upon reading the attribute back. You can use a helper method in your model, for example:

# schedule model
def start_in_zone(zone)
  self.start.strftime("%H:%M").in_time_zone(zone)
end

This will take only the hours and minutes part of the stored time and parse it in the given time zone with the date set to today. See this example:

"Sat, 01 Jan 2000 08:00:00".to_time.
     strftime("%H:%M").
     in_time_zone("Central Time (US & Canada)")
# => Tue, 12 Apr 2016 08:00:00 CDT -05:00

Upvotes: 1

Related Questions