Real World Rails DATE_FORMAT samples

date_time_formats.rb

~/dev/real-world-rails (master)
$ ag -G 'config/initializers/' ::DATE_FORMATS

apps/accelerated_claims/config/initializers/date_formats.rb
1:Date::DATE_FORMATS[:printed] = '%d %B %Y'

apps/advocate-defence-payments/config/initializers/date_time.rb
2:Date::DATE_FORMATS[:default] = Settings.date_format
5:DateTime::DATE_FORMATS[:default] = Settings.date_time_format
8:Time::DATE_FORMATS[:default] = Settings.date_time_format

apps/atet/config/initializers/formats.rb
1:Date::DATE_FORMATS[:long] = '%e %B %Y'

apps/c2/config/initializers/date_format.rb
1:Time::DATE_FORMATS[:timestamp] = "%-m/%-d/%Y %I:%M%p"
2:Time::DATE_FORMATS[:datestamp] = "%-m/%-d/%y"
4:Time::DATE_FORMATS[:pretty_datetime] = "%b %-d, %Y at %l:%M%P"
5:Time::DATE_FORMATS[:pretty_date] = "%b %-d, %Y at %l:%M%P"

apps/calagator/config/initializers/dates.rb
6:Time::DATE_FORMATS.merge!(my_formats)
7:Date::DATE_FORMATS.merge!(my_formats)

apps/cfp-app/config/initializers/time_formats.rb
1:Time::DATE_FORMATS[:month_day_year] = "%b %d, %Y"
2:Time::DATE_FORMATS[:long_with_zone] = "%b %-d, %Y at %I:%M%P %Z"
3:Time::DATE_FORMATS[:day_at_time] = "%-d %b @ %H:%M"
4:Time::DATE_FORMATS[:month_day] = "%b %d"

apps/courtfinder/config/initializers/date_formats.rb
1:Time::DATE_FORMATS.merge!(

apps/defence-request-service/config/initializers/date_formats.rb
1:Date::DATE_FORMATS[:full] = "%-d %B %Y"

apps/defence-request-service/config/initializers/time_formats.rb
1:Time::DATE_FORMATS[:time] = "%R"

apps/empirical-core/config/initializers/time_formats.rb
1:Time::DATE_FORMATS[:quill_default] = '%m/%d/%Y'

apps/errbit/config/initializers/time_formats.rb
1:Time::DATE_FORMATS[:micro] = '%b %d %l:%M%P'
2:Time::DATE_FORMATS[:precise] = '%b %d %H:%M:%S'

apps/feedbin/config/initializers/time.rb
1:Time::DATE_FORMATS[:feed] = "%B %d, %Y - %H:%M"
2:Time::DATE_FORMATS[:full_human] = "%B %e, %Y - %l:%M %p"
3:Time::DATE_FORMATS[:datetime] = "%FT%T%:z"
4:Time::DATE_FORMATS[:date] = "%B %e, %Y"
5:Time::DATE_FORMATS[:day_month] = "%b %d"
6:Time::DATE_FORMATS[:stats] = "%Y/%m/%d %H:%M:%S"

apps/fr-staffapp/config/initializers/date_time.rb
1:Date::DATE_FORMATS[:default] = '%d/%m/%Y'
2:Time::DATE_FORMATS[:default] = '%d/%m/%Y %H:%M'
3:Date::DATE_FORMATS[:gov_uk_long] = '%-d %B %Y'
4:Date::DATE_FORMATS[:gov_uk_short] = '%-d %b %Y'

apps/frontend/config/initializers/date_formats.rb
1:Date::DATE_FORMATS[:short_ordinal] = "%d %B %Y"
2:Time::DATE_FORMATS[:short_ordinal] = "%d %B %Y"

apps/gitlabhq/config/initializers/date_time_formats.rb
4:Date::DATE_FORMATS[:medium] = '%b %-d, %Y'
9:Time::DATE_FORMATS[:medium] = '%b %-d, %Y %-I:%M%P'

apps/growstuff/config/initializers/time_formats.rb
1:Time::DATE_FORMATS[:default] = '%B %d, %Y at %H:%M'
2:Date::DATE_FORMATS[:default] = "%B %d, %Y"
4:Time::DATE_FORMATS[:date] = "%B %d, %Y"
5:Date::DATE_FORMATS[:date] = "%B %d, %Y"
7:Date::DATE_FORMATS[:ymd] = "%Y-%m-%d"
9:Time::DATE_FORMATS[:datetime] = '%B %d, %Y at %H:%M'

apps/locomotivecms-engine/config/initializers/time_format.rb
2:Time::DATE_FORMATS[:humanized_ago]  = ->(time) do

apps/netguru-people/config/initializers/dates_format.rb
1:Time::DATE_FORMATS[:ymd] = '%Y-%m-%d'

apps/obtvse2/config/initializers/time_formats.rb
1:Time::DATE_FORMATS[:month_year] = "%B %Y"
2:Time::DATE_FORMATS[:day_month_year] = "%B %d, %Y"

apps/open-source-billing/config/initializers/time_formats.rb.rb
1:Date::DATE_FORMATS[:month_and_year] = "%B %Y"
2:Date::DATE_FORMATS[:short_mdy] = "%m %d %Y"

apps/opengovernment/config/initializers/time_formats.rb
1:Time::DATE_FORMATS.merge!(

apps/osem/config/initializers/time_formats.rb
1:Time::DATE_FORMATS[:db_without_seconds] = '%Y-%m-%d %H:%M'

apps/parliamentary-questions/config/initializers/date_formats.rb
1:Date::DATE_FORMATS[:default] = '%d/%m/%Y'
2:Date::DATE_FORMATS[:db] = '%Y-%m-%d'
3:Date::DATE_FORMATS[:export] = '%Y-%m-%d'
4:Date::DATE_FORMATS[:date] = '%d/%m/%Y'

apps/parliamentary-questions/config/initializers/time_formats.rb
1:Time::DATE_FORMATS[:default] = '%d/%m/%Y %H:%M'
2:Time::DATE_FORMATS[:wordy] = 'on <strong>%d/%m/%Y</strong> at <strong>%H:%M</strong>'
3:Time::DATE_FORMATS[:db] = '%Y-%m-%d %H:%M:%S'
4:Time::DATE_FORMATS[:export] = '%Y-%m-%d %H:%M'
5:Time::DATE_FORMATS[:date] = '%d/%m/%Y'

apps/peatio/config/initializers/date_time_format.rb
1:Date::DATE_FORMATS[:short] = '%m-%d'
2:Time::DATE_FORMATS[:default] = "%Y-%m-%d %H:%M:%S"

apps/present/config/initializers/time_formats.rb
1:Time::DATE_FORMATS[:ymd_dash] = '%Y-%m-%d'
2:Time::DATE_FORMATS[:mon_year] = '%b %Y'
3:Time::DATE_FORMATS[:mdy] = '%-m/%-d/%y'
4:Time::DATE_FORMATS[:md] = '%-m/%-d'
5:Time::DATE_FORMATS[:md_wd] = '%a %-m/%-d'

apps/remit/config/initializers/date_formats.rb
1:Date::DATE_FORMATS[:short_ordinal] = lambda do |date|
4:Date::DATE_FORMATS[:medium_ordinal] = lambda do |date|

apps/remit/config/initializers/time_formats.rb
1:Time::DATE_FORMATS[:short_ordinal] = lambda do |time|
4:Time::DATE_FORMATS[:medium_ordinal] = lambda do |time|

apps/scumblr/config/initializers/date_formats.rb
16:Date::DATE_FORMATS[:default]="%b %e %Y"
17:Time::DATE_FORMATS[:default]="%b %e %Y %H:%M"

apps/spina/config/initializers/time_formats.rb
1:Time::DATE_FORMATS[:w3c] = lambda {|time| time.utc.strftime("%Y-%m-%dT%H:%M:%S+00:00") }

apps/whitehall/config/initializers/formats.rb
1:Date::DATE_FORMATS[:long_ordinal] = lambda { |date| date.strftime("%e %B %Y").strip }
2:Date::DATE_FORMATS[:short_ordinal] = "%B %Y"
3:Date::DATE_FORMATS[:uk_short] = lambda { |date| date.strftime("%d/%m/%Y").strip }
4:Time::DATE_FORMATS[:long_ordinal] = lambda { |time| time.strftime("%e %B %Y %H:%M").strip }
5:Time::DATE_FORMATS[:date_with_time] = lambda { |time| [time.strftime("%e %B %Y").strip, time.strftime("%l:%M%P").strip].join(' ') }
6:Time::DATE_FORMATS[:one_month_precision] = "%B %Y"
7:Time::DATE_FORMATS[:two_month_precision] = lambda do |time|

~/dev/real-world-rails (master)
$ ag -G 'config/initializers/' ::DATE_FORMATS

Excellent list. To my bookmarks. Would be great if an example of the output is added somewhere