Date and time formats for pirates

Need to display a date in your Rails app? First try:

Time.now.strftime "arrrround %H'ish"

To remove duplication, you imagine a time format initializer. Second try:

Time.now.to_s :pirate

Then you remember the :default localized key. Third time’s a charm:

l Time.now

It formats based on the config/locales/en.yml file:

en:
  time:
    formats:
      default: "arrrround %H'ish"
  date:
    formats:
      default: "arrrround %H'ish"

Dates work, too:

l Date.today

The same system lets you alter the display of “days ago” and “minute from now.”

Time.now is on my side

I needed an open? method. First try:

def open?
  opens_at < Time.now < closes_at
end

However, Ruby doesn’t support that kind of expression. Second try:

def open?
  (opens_at < Time.now) && (Time.now < closes_at)
end

It’s noisy and lacks expression. Third time’s a charm:

def open?
  Time.now.between? opens_at, closes_at
end

Ship it.

Custom formats for DateTime

Date::DATE_FORMATS is quite helpful. It lets you do this:

Date.today.to_s(:custom)

with only this code in config/initializers/date_format.rb:

Date::DATE_FORMATS[:custom] = "%Y-%m-%d"

To do the same thing for DateTime instances, like created_at columns, use Time::DATE_FORMATS.

Time::DATE_FORMATS

To set the default format for either one, set DATE_FORMATS[:default]. This will cause <%= item.created_at %> to output “2011-08-16”, with no extra work from you.

The More You Know: custom time descriptions

Fred asked if we could shorten the “about 1 month ago” text in an information-rich table that was squeezing the created_at data.

I’m not familiar with the i18n API beyond supporting internationalization in Clearance. Therefore, it took me mildly by surprise when I learned that you can override distance_in_words with the i18n API (and, by extension, time_ago_in_words).

Speaks English real good

i18n is the right tool to solve a problem like this even in an English-only application. A quick change to config/locales/en.yml, however, and we’re done:

en:
  datetime:
    distance_in_words:
      less_than_x_seconds:
        other: '1 minute'
      half_a_minute: '1 minute'
      less_than_x_minutes:
        one: '1 minute'
      x_minutes:
        one: '1 minute'
        other: '{{count}} minutes'
      about_x_hours:
        one: '1 hour'
        other: '{{count}} hours'
      about_x_months:
        one: '1 month'
        other: '{{count}} months'
      about_x_years:
        one: '1 year'
        other: '{{count}} years'
      over_x_years:
        one: 'over 1 year'
        other: 'over {{count}} years'

The result:

You can see other options in svenfuchs/i18n.

fundamentals: TDD a date helper

I want to format a date range in a view for our training app. This is a job for helpers. A fundamental skill for Rails developers is writing the helper using TDD. This process takes about 10 minutes and results in a confidence-building regression suite.

Working outside-in, we start in the interface:

<%= format_date_range(course.date_range) %>

Tests fail, “format_date_range” doesn’t exist.

script/generate helper date_time

Produces:

# app/helpers/date_time_helper.rb
module DateTimeHelper
end

# test/unit/helpers/date_time_helper_test.rb
require 'test_helper'

class DateTimeHelperTest < ActionView::TestCase
end

Incidentally, former thoughtbot intern Eugene Bolshakov wrote the Rails patch that creates the helper test stub generator.

First case:

should "format date range on same day" do
  eight_oclock = DateTime.new(2009, 10, 12, 8)
  nine_oclock  = DateTime.new(2009, 10, 12, 9)
  date_range   = eight_oclock..nine_oclock
  expected     = "October 12, 2009"

  assert_equal expected, format_date_range(date_range)
end

My style is flat test structure, intention-revealing temporary variables, respect an 80-character line limit.

Make it pass:

def format_date_range(date_range)
  first = date_range.first
  last  = date_range.last
  if same_day?(first, last)
    "#{first.to_s(:month_day)}, #{first.year}"
  end
end

private

def same_day?(date_one, date_two)
  date_one.day == date_two.day
end

More temporary variables. Simple private method is there for a more expressive question in the conditional.

Next case:

should "format date range on different days of same month" do
  monday     = DateTime.new(2009, 10, 12)
  tuesday    = DateTime.new(2009, 10, 13)
  date_range = monday..tuesday
  expected   = "October 12-13, 2009"

  assert_equal expected, format_date_range(date_range)
end

Same pattern. Make it pass:

def format_date_range(date_range)
  # ...
  elsif same_month?(first, last)
    "#{first.to_s(:month_day)}-#{last.day}, #{last.year}"
  end
end

private

def same_month?(date_one, date_two)
  date_one.month == date_two.month
end

Same pattern. Date and time formatting already has a home in config/initializers/time_formats.rb, so we’re using our existing date format, month_day. Here’s what my typical initializer looks like:

{ :short_date  => "%x",                 # 04/13/10
  :long_date   => "%a, %b %d, %Y",      # Tue, Apr 13, 2010
  :longer_date => "%B %d, %Y %H:%M %Z", # April 13, 2010 11:20
  :index       => "%Y/%m/%d %H:%M",     # 2010/04/13 11:20
  :standard    => "%B %d, %Y",          # April 13, 2010
  :month_day   => "%B %d",              # April 13
  :abbr_month  => "%b"                  # Apr
}.each do |key, value|
  ActiveSupport::CoreExtensions::Time::Conversions::DATE_FORMATS.update(
    key => value
  )
end

Final case:

should "format date range on days of different months" do
  october    = DateTime.new(2009, 10, 31)
  november   = DateTime.new(2009, 11, 1)
  date_range = october..november
  expected   = "October 31-November 01, 2009"

  assert_equal expected, format_date_range(date_range)
end

Make it pass:

else
  "#{first.to_s(:month_day)}-#{last.to_s(:month_day)}, #{last.year}"
end

There’s room for improvement: that leading zero sucks. We could use %e instead of %d, which replaces the leading zero with a space:

expected   = "October 31-November  1, 2009"

That makes the test look a little ridiculous, but since the output will be HTML, the extra space is fine.

Make it pass:

:month_day   => "%B %e"

Complete source code.

Sneak peak of the app in progress, taking advantage of the date helper: