How to Work With Time Zones in Rails
With different time zones
When dealing with time zones in Rails, there is one key fact to keep in mind:
Rails has configurable time zones, while
Ruby is always in the server's time zone
Thus, using Ruby's time API will give you wrong results for different time zones.
For consistency, you should only use Rails' methods, but the hard thing is to know which method originates from Ruby and which from Rails. To simplify this, adhere to the following suggestion:
Use
Time.zone
for everything time-related
Copy# Example usage of Time.zone Time.zone.now # instead of Time.now, DateTime.now Time.zone.today # instead of Date.today Time.zone.local(...) # instead of Date.new, DateTime.new Time.zone.at(...) # instead of Time.at Time.zone.parse(...) # instead of Time.parse date.beginning_of_day # instead of date.to_time
Things like 2.hours.ago
work as expected, because they're provided by Rails. Still, prefer using Time.zone.now + 2.hours
as it will leave no doubt about time zones being respected.
In case you should get time objects without time zone information, you can still turn them into zoned times by calling #in_time_zone
, e.g.: Time.now.in_time_zone
.
"Without" time zones
You can not actually "disable" time zones, because their existence is a fact. You can, however, tell Rails the only single time zone you'll need is the server's.
Copyconfig.time_zone = "Berlin" # Local time zone config.active_record.default_timezone = :local config.active_record.time_zone_aware_attributes = false
Now you may again use both Ruby's and Rails' whole time API.
Reference
- The Exhaustive Guide to Rails Time Zones Archive - a quick introduction to how and why things can go wrong when you're using time zones
- Working with or without time zones in Rails applications
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