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 for everything time-related

# Example usage of # instead of, # instead of # instead of, # instead of # 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 + 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.:

"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.

config.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.


Dominik Schöler about 6 years ago
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