Question

I’m not sure how to start… I’m not sure why ActiveSupport::TimeZone is even necessary, since TZInfo::Timezone seems to work just fine, and be more complete… but we had been using ActiveSupport for some reason, and I was unable to find the EST timezone in the available timezones. Am I missing something? Is there any reason that’s not included?

Is there any reason not to use TZInfo? Should everyone just be using TZInfo?

Answer 1

The TimeZone class serves as a wrapper around TZInfo::Timezone instances. It allows Rails to do the following:

• Limit the set of zones provided by TZInfo to a meaningful subset of 142 zones
• Retrieve and display zones with a friendlier name (e.g., “Eastern Time (US & Canada)” instead of “America/New_York”)
• Lazily load TZInfo::Timezone instances only when they’re needed
• Create ActiveSupport::TimeWithZone instances via TimeZone’s local, parse, at and now methods.

Source: The Rails 3 Way – 2nd Edition

EST is provided for in ActiveSupport::TimeZone, it’s named “Eastern Time (US & Canada)”. You can see all the time zones provided by ActiveSupport::TimeZone by calling TimeZone.all (provided ActiveSupport is included). EST is also included in US time zones, you can return a smaller collection of US-only time zones by calling TimeZone.us_zones. Accessing the TimeZone collection will provide a TimeZone preceded by it’s offset eg. TimeZone(“Eastern Time (US & Canada)”] => (GMT-05:00) Eastern Time (US & Canada).