parse

Takes a string representation of a Time and attempts to parse it using a heuristic.

require 'time'

Time.parse("2010-10-31") #=> 2010-10-31 00:00:00 -0500

Any missing pieces of the date are inferred based on the current date.

require 'time'

# assuming the current date is "2011-10-31"
Time.parse("12:00") #=> 2011-10-31 12:00:00 -0500

We can change the date used to infer our missing elements by passing a second object that responds to #mon, #day and #year, such as Date, Time or DateTime. We can also use our own object.

require 'time'

class MyDate
  attr_reader :mon, :day, :year

  def initialize(mon, day, year)
    @mon, @day, @year = mon, day, year
  end
end

d  = Date.parse("2010-10-28")
t  = Time.parse("2010-10-29")
dt = DateTime.parse("2010-10-30")
md = MyDate.new(10,31,2010)

Time.parse("12:00", d)  #=> 2010-10-28 12:00:00 -0500
Time.parse("12:00", t)  #=> 2010-10-29 12:00:00 -0500
Time.parse("12:00", dt) #=> 2010-10-30 12:00:00 -0500
Time.parse("12:00", md) #=> 2010-10-31 12:00:00 -0500

If a block is given, the year described in date is converted by the block. This is specifically designed for handling two digit years. For example, if you wanted to treat all two digit years prior to 70 as the year 2000+ you could write this:

require 'time'

Time.parse("01-10-31") {|year| year + (year < 70 ? 2000 : 1900)}
#=> 2001-10-31 00:00:00 -0500
Time.parse("70-10-31") {|year| year + (year < 70 ? 2000 : 1900)}
#=> 1970-10-31 00:00:00 -0500

If the upper components of the given time are broken or missing, they are supplied with those of now. For the lower components, the minimum values (1 or 0) are assumed if broken or missing. For example:

require 'time'

# Suppose it is "Thu Nov 29 14:33:20 2001" now and
# your time zone is EST which is GMT-5.
now = Time.parse("Thu Nov 29 14:33:20 2001")
Time.parse("16:30", now)     #=> 2001-11-29 16:30:00 -0500
Time.parse("7/23", now)      #=> 2001-07-23 00:00:00 -0500
Time.parse("Aug 31", now)    #=> 2001-08-31 00:00:00 -0500
Time.parse("Aug 2000", now)  #=> 2000-08-01 00:00:00 -0500

Since there are numerous conflicts among locally defined time zone abbreviations all over the world, this method is not intended to understand all of them. For example, the abbreviation “CST” is used variously as:

-06:00 in America/Chicago,
-05:00 in America/Havana,
+08:00 in Asia/Harbin,
+09:30 in Australia/Darwin,
+10:30 in Australia/Adelaide,
etc.

Based on this fact, this method only understands the time zone abbreviations described in RFC 822 and the system time zone, in the order named. (i.e. a definition in RFC 822 overrides the system time zone definition.) The system time zone is taken from Time.local(year, 1, 1).zone and Time.local(year, 7, 1).zone. If the extracted time zone abbreviation does not match any of them, it is ignored and the given time is regarded as a local time.

ArgumentError is raised if Date._parse cannot extract information from date or if the Time class cannot represent specified date.

This method can be used as a fail-safe for other parsing methods as:

Time.rfc2822(date) rescue Time.parse(date)
Time.httpdate(date) rescue Time.parse(date)
Time.xmlschema(date) rescue Time.parse(date)

A failure of Time.parse should be checked, though.

You must require ‘time’ to use this method.