Fix handling of offsets with Time#to_s(:iso8601)

Use a lambda to ensure that the generated string respects the offset of
the time value. Also add DateTime#to_s(:iso8601) and Date#to_s(:iso8601)
for completeness.

activesupport/CHANGELOG.md

-*   Add Time#to_s(:iso8601) for easy conversion of times to the iso8601 format for easy Javascript date parsing.
+*   Add `DateTime#to_s(:iso8601)` and `Date#to_s(:iso8601)` for consistency.
+
+    *Andrew White*
+
+*   Add `Time#to_s(:iso8601)` for easy conversion of times to the iso8601 format for easy Javascript date parsing.
 
     *DHH*
 

activesupport/lib/active_support/core_ext/date/conversions.rb

@@ -12,7 +12,8 @@ class Date
       day_format = ActiveSupport::Inflector.ordinalize(date.day)
       date.strftime("%B #{day_format}, %Y") # => "April 25th, 2007"
     },
-    :rfc822       => '%e %b %Y'
+    :rfc822       => '%e %b %Y',
+    :iso8601      => lambda { |date| date.iso8601 }
   }
 
   # Ruby 1.9 has Date#to_time which converts to localtime only.
@@ -34,6 +35,7 @@ class Date
   #   date.to_formatted_s(:long)          # => "November 10, 2007"
   #   date.to_formatted_s(:long_ordinal)  # => "November 10th, 2007"
   #   date.to_formatted_s(:rfc822)        # => "10 Nov 2007"
+  #   date.to_formatted_s(:iso8601)       # => "2007-11-10"
   #
   # == Adding your own time formats to to_formatted_s
   # You can add your own formats to the Date::DATE_FORMATS hash.

activesupport/lib/active_support/core_ext/date_time/conversions.rb

@@ -19,6 +19,7 @@ class DateTime
   #   datetime.to_formatted_s(:long)          # => "December 04, 2007 00:00"
   #   datetime.to_formatted_s(:long_ordinal)  # => "December 4th, 2007 00:00"
   #   datetime.to_formatted_s(:rfc822)        # => "Tue, 04 Dec 2007 00:00:00 +0000"
+  #   datetime.to_formatted_s(:iso8601)       # => "2007-12-04T00:00:00+00:00"
   #
   # == Adding your own datetime formats to to_formatted_s
   # DateTime formats are shared with Time. You can add your own to the

activesupport/lib/active_support/core_ext/time/conversions.rb

@@ -17,7 +17,7 @@ class Time
       offset_format = time.formatted_offset(false)
       time.strftime("%a, %d %b %Y %H:%M:%S #{offset_format}")
     },
-    :iso8601      => "%Y-%m-%dT%H:%M:%SZ"
+    :iso8601      => lambda { |time| time.iso8601 }
   }
 
   # Converts to a formatted string. See DATE_FORMATS for builtin formats.
@@ -35,6 +35,7 @@ class Time
   #   time.to_formatted_s(:long)         # => "January 18, 2007 06:10"
   #   time.to_formatted_s(:long_ordinal) # => "January 18th, 2007 06:10"
   #   time.to_formatted_s(:rfc822)       # => "Thu, 18 Jan 2007 06:10:17 -0600"
+  #   time.to_formatted_s(:iso8601)      # => "2007-01-18T06:10:17-06:00"
   #
   # == Adding your own time formats to +to_formatted_s+
   # You can add your own formats to the Time::DATE_FORMATS hash.

activesupport/test/core_ext/date_ext_test.rb

@@ -25,6 +25,7 @@ def test_to_s
     assert_equal "February 21st, 2005", date.to_s(:long_ordinal)
     assert_equal "2005-02-21",          date.to_s(:db)
     assert_equal "21 Feb 2005",         date.to_s(:rfc822)
+    assert_equal "2005-02-21",          date.to_s(:iso8601)
   end
 
   def test_readable_inspect

activesupport/test/core_ext/date_time_ext_test.rb

@@ -18,6 +18,12 @@ def test_to_s
     assert_equal "Mon, 21 Feb 2005 14:30:00 +0000",   datetime.to_s(:rfc822)
     assert_equal "February 21st, 2005 14:30",         datetime.to_s(:long_ordinal)
     assert_match(/^2005-02-21T14:30:00(Z|\+00:00)$/,  datetime.to_s)
+
+    with_env_tz "US/Central" do
+      assert_equal "2009-02-05T14:30:05-06:00", DateTime.civil(2009, 2, 5, 14, 30, 5, Rational(-21600, 86400)).to_s(:iso8601)
+      assert_equal "2008-06-09T04:05:01-05:00", DateTime.civil(2008, 6, 9, 4, 5, 1, Rational(-18000, 86400)).to_s(:iso8601)
+      assert_equal "2009-02-05T14:30:05+00:00", DateTime.civil(2009, 2, 5, 14, 30, 5).to_s(:iso8601)
+    end
   end
 
   def test_readable_inspect

activesupport/test/core_ext/time_ext_test.rb

@@ -503,13 +503,15 @@ def test_to_s
     assert_equal "20050221174430123456789",         time.to_s(:nsec)
     assert_equal "February 21, 2005 17:44",         time.to_s(:long)
     assert_equal "February 21st, 2005 17:44",       time.to_s(:long_ordinal)
-    assert_equal "2009-02-05T14:30:05Z", Time.local(2009, 2, 5, 14, 30, 5).to_s(:iso8601)
     with_env_tz "UTC" do
       assert_equal "Mon, 21 Feb 2005 17:44:30 +0000", time.to_s(:rfc822)
     end
     with_env_tz "US/Central" do
       assert_equal "Thu, 05 Feb 2009 14:30:05 -0600", Time.local(2009, 2, 5, 14, 30, 5).to_s(:rfc822)
       assert_equal "Mon, 09 Jun 2008 04:05:01 -0500", Time.local(2008, 6, 9, 4, 5, 1).to_s(:rfc822)
+      assert_equal "2009-02-05T14:30:05-06:00", Time.local(2009, 2, 5, 14, 30, 5).to_s(:iso8601)
+      assert_equal "2008-06-09T04:05:01-05:00", Time.local(2008, 6, 9, 4, 5, 1).to_s(:iso8601)
+      assert_equal "2009-02-05T14:30:05Z", Time.utc(2009, 2, 5, 14, 30, 5).to_s(:iso8601)
     end
   end