Format the date using Ruby on Rails

Question

The flickr api provides a posted date as unix timestamp one: "The posted date is always passed around as a unix timestamp, which is an unsigned integer specifying the number of seconds since Jan 1st 1970 GMT."

For example, here is the date '1100897479'. How do I format it using Ruby on Rails?

Answer 1

@CMW's answer is bang on the money. I've added this answer as an example of how to configure an initializer so that both Date and Time objects get the formatting

config/initializers/time_formats.rb

date_formats = {
  concise: '%d-%b-%Y' # 13-Jan-2014
}

Time::DATE_FORMATS.merge! date_formats
Date::DATE_FORMATS.merge! date_formats

Also the following two commands will iterate through all the DATE_FORMATS in your current environment, and display today's date and time in each format:

Date::DATE_FORMATS.keys.each{|k| puts [k,Date.today.to_formatted_s(k)].join(':- ')}
Time::DATE_FORMATS.keys.each{|k| puts [k,Time.now.to_formatted_s(k)].join(':- ')}

Answer 2

Have a look at localize, or l

eg:

l Time.at(1100897479)

Answer 3

Here's my go at answering this,

so first you will need to convert the timestamp to an actual Ruby Date/Time. If you receive it just as a string or int from facebook, you will need to do something like this:

my_date = Time.at(timestamp_from_facebook.to_i)

OK, so now assuming you already have your date object...

to_formatted_s is a handy Ruby function that turns dates into formatted strings.

Here are some examples of its usage:

time = Time.now                     # => Thu Jan 18 06:10:17 CST 2007    

time.to_formatted_s(:time)          # => "06:10"
time.to_s(:time)                    # => "06:10"    

time.to_formatted_s(:db)            # => "2007-01-18 06:10:17"
time.to_formatted_s(:number)        # => "20070118061017"
time.to_formatted_s(:short)         # => "18 Jan 06:10"
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"

As you can see: :db, :number, :short ... are custom date formats.

To add your own custom format, you can create this file: config/initializers/time_formats.rb and add your own formats there, for example here's one:

Date::DATE_FORMATS[:month_day_comma_year] = "%B %e, %Y" # January 28, 2015

Where :month_day_comma_year is your format's name (you can change this to anything you want), and where %B %e, %Y is unix date format.

Here's a quick cheatsheet on unix date syntax, so you can quickly setup your custom format:

From http://linux.die.net/man/3/strftime    

  %a - The abbreviated weekday name (``Sun'')
  %A - The  full  weekday  name (``Sunday'')
  %b - The abbreviated month name (``Jan'')
  %B - The  full  month  name (``January'')
  %c - The preferred local date and time representation
  %d - Day of the month (01..31)
  %e - Day of the month without leading 0 (1..31) 
  %g - Year in YY (00-99)
  %H - Hour of the day, 24-hour clock (00..23)
  %I - Hour of the day, 12-hour clock (01..12)
  %j - Day of the year (001..366)
  %m - Month of the year (01..12)
  %M - Minute of the hour (00..59)
  %p - Meridian indicator (``AM''  or  ``PM'')
  %S - Second of the minute (00..60)
  %U - Week  number  of the current year,
          starting with the first Sunday as the first
          day of the first week (00..53)
  %W - Week  number  of the current year,
          starting with the first Monday as the first
          day of the first week (00..53)
  %w - Day of the week (Sunday is 0, 0..6)
  %x - Preferred representation for the date alone, no time
  %X - Preferred representation for the time alone, no date
  %y - Year without a century (00..99)
  %Y - Year with century
  %Z - Time zone name
  %% - Literal ``%'' character    

   t = Time.now
   t.strftime("Printed on %m/%d/%Y")   #=> "Printed on 04/09/2003"
   t.strftime("at %I:%M%p")            #=> "at 08:56AM"

Hope this helped you. I've also made a github gist of this little guide, in case anyone prefers.

Answer 4

Once you have parsed the timestamp string and have a time object (see other answers for details), you can use Time.to_formatted_s from Rails. It has several formats built in that you can specify with symbols.

Quote:

time = Time.now                     # => Thu Jan 18 06:10:17 CST 2007

time.to_formatted_s(:time)          # => "06:10"
time.to_s(:time)                    # => "06:10"

time.to_formatted_s(:db)            # => "2007-01-18 06:10:17"
time.to_formatted_s(:number)        # => "20070118061017"
time.to_formatted_s(:short)         # => "18 Jan 06:10"
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_s is an alias)

You can also define your own formats - usually in an initializer (Thanks to Dave Newton for pointing this out). This is how it's done:

# config/initializers/time_formats.rb
Time::DATE_FORMATS[:month_and_year] = "%B %Y"
Time::DATE_FORMATS[:short_ordinal] = lambda { |time| time.strftime("%B #{time.day.ordinalize}") }

Answer 5

Since the timestamps are seconds since the UNIX epoch, you can use DateTime.strptime ("string parse time") with the correct specifier:

Date.strptime('1100897479', '%s')
#=> #<Date: 2004-11-19 ((2453329j,0s,0n),+0s,2299161j)>
Date.strptime('1100897479', '%s').to_s
#=> "2004-11-19"
DateTime.strptime('1100897479', '%s')
#=> #<DateTime: 2004-11-19T20:51:19+00:00 ((2453329j,75079s,0n),+0s,2299161j)>
DateTime.strptime('1100897479', '%s').to_s
#=> "2004-11-19T20:51:19+00:00"

Note that you have to require 'date' for that to work, then you can call it either as Date.strptime (if you only care about the date) or DateTime.strptime (if you want date and time). If you need different formatting, you can call DateTime#strftime (look at strftime.net if you have a hard time with the format strings) on it or use one of the built-in methods like rfc822.

Answer 6

First you will need to convert the timestamp to an actual Ruby Date/Time. If you receive it just as a string or int from facebook, you will need to do something like this:

my_date = Time.at(timestamp_from_facebook.to_i)

Then to format it nicely in the view, you can just use to_s (for the default formatting):

<%= my_date.to_s %>

Note that if you don't put to_s, it will still be called by default if you use it in a view or in a string e.g. the following will also call to_s on the date:

<%= "Here is a date: #{my_date}" %>

or if you want the date formatted in a specific way (eg using "d/m/Y") - you can use strftime as outlined in the other answer.

Answer 7

Easiest is to use strftime (docs).

If it's for use on the view side, better to wrap it in a helper, though.