Time zone in Rails
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This document discusses time zone handling in Rails applications. It recommends: 1. Configuring ActiveRecord to use UTC as the default time zone and setting the application time zone. 2. Being careful with time zone conversions and aware that the meaning of times can change depending on the time zone. Dates like birthdays need special handling for time zones offset by more than 12 hours. 3. Following coding best practices like using Time.zone.now.utc and avoiding direct time conversions to avoid time zone issues. Proper time zone handling is important to avoid bugs.
Time zone in Rails
- 1. Time zone in Rails Shinjuku.rb #34 Yuki Matsukura
- 2. Today’s topic • gem “zonebie” • Understanding time zone issues • Case study
- 3. https://spike.cc/ • DB – UTC • Program – UTC • View – Multi time zone.
- 4. Software stack 1. config.active_record.default_timezone 2. config.time_zone 3. View
- 5. Approach 1
- 7. CASE STUDY
- 8. > require 'timecop’ > Timecop.freeze(Time.utc(2015, 12, 31, 23, 0, 0)) > Time.zone = 'Tokyo’ > Time.zone.now.utc.month == Date.today.month => false
- 9. Both are correct, but different validates_inclusion_of :birth_day, in: 130.years.ago.utc..20.years.ago.utc validates_inclusion_of :birth_day, in: 130.years.ago..20.years.ago
- 10. Special time zones, > 12
- 11. Be careful with birthday handling. • 1982-06-04 +13:00 – Physically born on 6/5 – Logically born on 6/4
- 12. Meaning is different. > 60.days.since(Time.utc(2014, 2, 7, 23, 59, 59).in_time_zone('Wellington')).utc > 60.days.since(Time.utc(2014, 2, 7, 23, 59, 59).in_time_zone('Wellington').utc)
- 13. Need to care about time zone conversion > 60.days.since(Time.utc(2014, 2, 7, 23, 59, 59).in_time_zone('Wellington')).utc => 2014-04-09 00:59:59 UTC > 60.days.since(Time.utc(2014, 2, 7, 23, 59, 59).in_time_zone('Wellington').utc) => 2014-04-08 23:59:59 UTC
- 14. Example • Bad – Time.now – Time.zone.today – Time.parse('2013/10/01’) – Time.utc(2013,10,1) • Bad (Might work some cases) – Time.zone.now – 1.hour.ago – Time.zone.parse('2013/10/01’) • Instance’s timezone depends on context. – DateTime.now.utc • To avoid using DateTime class • Good – Time.zone.now.utc – 1.year.since.utc – 3.months.ago.utc.to_date • (Time.zone.now.utc.to_date - 3.months) – Time.utc(2007, 2, 10, 20, 30, 45).in_time_zone('UTC') – Time.zone.parse('2016-02-10T00:00:00+09:00’)
- 15. CODING RULE
- 16. Programming issue • 1. Ruby and Rails time zone – http://qiita.com/joker1007/items/2c277cca5bd50 e4cce5e • 2. Coding rule
- 17. Time zone coding rule • Convert time zone to UTC • Avoid to convert to numeric. – xxx.year, xxx.month