Date and Time Localization and Formatting

Installation

Note that ex_cldr_dates_times requires Elixir 1.12 or later.

Add ex_cldr_dates_time as a dependency to your mix project:

defp deps do
  [
    {:ex_cldr_dates_times, "~> 2.0"}
  ]
end

then retrieve ex_cldr_dates_times from hex:

mix deps.get
mix deps.compile

Configuring a required backend module

ex_cldr_dates_times uses the configuration set for the dependency ex_cldr. See the documentation for ex_cldr.

A backend module is required that is used to host the functions that manage CLDR data. An example to get started is:

1. Create a backend module (see ex_cldr for details of the available options). Note the requirement to configure the appropriate Cldr provider backends.

   defmodule MyApp.Cldr do
     use Cldr,
       locales: ["en", "fr", "ja"],
       providers: [Cldr.Number, Cldr.Calendar, Cldr.DateTime]
   
   end

2. [Optional] Update config.exs configuration to specify this backend as the system default. Not required, but often useful.

   config :ex_cldr,
     default_locale: "en",
     default_backend: MyApp.Cldr

Introduction

ex_cldr_dates_times is an addon library application for ex_cldr that provides localisation and formatting for dates, times and date_times.

The primary API is MyApp.Cldr.Date.to_string/2, MyApp.Cldr.Time.to_string/2, MyApp.Cldr.DateTime.to_string/2 and MyApp.Cldr.DateTime.Relative.to_string/2. In the following examples MyApp refers to a CLDR backend module that must be defined by the developer:

iex> MyApp.Cldr.Date.to_string ~D[2020-05-30]
{:ok, "May 30, 2020"}

iex> MyApp.Cldr.Time.to_string ~U[2020-05-30 03:52:56Z]
{:ok, "3:52:56 AM"}

iex> MyApp.Cldr.DateTime.to_string ~U[2020-05-30 03:52:56Z]
{:ok, "May 30, 2020, 3:52:56 AM"}

# Note that if options are provided, a backend
# module is also required
iex> MyApp.Cldr.DateTime.Relative.to_string 1, unit: :day, format: :narrow
{:ok, "tomorrow"}

For help in iex:

iex> h MyApp.Cldr.Date.to_string
iex> h MyApp.Cldr.Time.to_string
iex> h MyApp.Cldr.DateTime.to_string
iex> h MyApp.Cldr.DateTime.Relative.to_string

Date, Time and DateTime Localization Formats

Dates, Times and DateTimes can be formatted using standard formats, format strings or format IDs.

• Standard formats provide cross-locale standardisation and therefore should be preferred where possible. The format types, implemented for MyApp.Cldr.Date.to_string/2, MyApp.Cldr.Time.to_string/2,MyApp.Cldr.DateTime.to_string/2 are :short, :medium, :long and :full. The default is :medium. For example, assuming a configured backend called MyApp.Cldr:

  iex> MyApp.Cldr.DateTime.to_string ~U[2020-05-30 03:52:56Z], format: :short
  {:ok, "5/30/20, 3:52 AM"}
  
  iex> MyApp.Cldr.DateTime.to_string ~U[2020-05-30 03:52:56Z], format: :long
  {:ok, "May 30, 2020 at 3:52:56 AM UTC"}
  
  iex> MyApp.Cldr.DateTime.to_string ~U[2020-05-30 03:52:56Z], format: :medium
  {:ok, "May 30, 2020, 3:52:56 AM"}
  
  iex> MyApp.Cldr.DateTime.to_string ~U[2020-05-30 03:52:56Z], format: :long, locale: "fr"
  {:ok, "30 mai 2020 à 03:52:56 UTC"}

• Format strings use one or more formatting symbols to define what date and time elements should be placed in the format. A simple example to format the time into hours and minutes:

  iex> MyApp.Cldr.DateTime.to_string ~U[2020-05-30 03:52:56Z], format: "hh:mm"
  {:ok, "03:52"}

• Format IDs are an atom that is a key into a map of formats defined by CLDR. These format IDs are returned by MyApp.Cldr.DateTime.Format.date_time_available_formats/2 (assuming your backend is MyApp.Cldr). The set of common format names across all locales configured in ex_cldr can be returned by MyApp.Cldr.DateTime.Format.common_date_time_format_names/0.

  iex> MyApp.Cldr.DateTime.Format.date_time_available_formats()
  %{mmmm_w_count_one: "'week' W 'of' MMMM", gy_mmm: "MMM y G", md: "M/d",
  mmm_md: "MMMM d", e_hms: "E HH:mm:ss", ed: "d E", y_mmm: "MMM y",
  e_hm: "E HH:mm", mmm_ed: "E, MMM d", y_mmm_ed: "E, MMM d, y",
  gy_mm_md: "MMM d, y G", mmm: "LLL", y_md: "M/d/y", gy: "y G",
  hms: "h:mm:ss a", hm: "h:mm a", y_mmmm: "MMMM y", m: "L",
  gy_mmm_ed: "E, MMM d, y G", y_qqq: "QQQ y", e: "ccc", y_qqqq: "QQQQ y",
  hmsv: "h:mm:ss a v", mmmm_w_count_other: "'week' W 'of' MMMM",
  ehm: "E h:mm a", y_m_ed: "E, M/d/y", h: "h a", hmv: "h:mm a v",
  yw_count_other: "'week' w 'of' y", mm_md: "MMM d", y_m: "M/y", m_ed: "E, M/d",
  ms: "mm:ss", d: "d", y_mm_md: "MMM d, y", yw_count_one: "'week' w 'of' y",
  y: "y", ehms: "E h:mm:ss a"}
  
  # These format types can be invoked for any locale - meaning
  # these format names are defined for all configured locales.
  iex> MyApp.Cldr.DateTime.Format.common_date_time_format_names()
  [:gy_mmm, :md, :mmm_md, :e_hms, :ed, :y_mmm, :e_hm, :mmm_ed, :y_mmm_ed,
  :gy_mm_md, :mmm, :y_md, :gy, :hms, :hm, :y_mmmm, :m, :gy_mmm_ed, :y_qqq, :e,
  :y_qqqq, :hmsv, :mmmm_w_count_other, :ehm, :y_m_ed, :h, :hmv, :yw_count_other,
  :mm_md, :y_m, :m_ed, :ms, :d, :y_mm_md, :y, :ehms]
  
  iex> Cldr.DateTime.to_string ~U[2020-05-30 03:52:56Z], MyApp.Cldr, format: :gy_mmm_ed
  {:ok, "Sat, May 30, 2020 AD"}
  
  iex(2)> Cldr.Time.to_string ~U[2020-05-30 03:52:56Z], MyApp.Cldr, format: :hm
  {:ok, "3:52 AM"}
  
  iex(3)> Cldr.Date.to_string ~U[2020-05-30 03:52:56Z], MyApp.Cldr, format: :yMd
  {:ok, "5/30/2020"}

Format strings

The CLDR standard defines a wide range of format symbols. Most - but not all - of these symbols are supported in Cldr. The supported symbols are described below. Note the known restrictions and limitations.

Element	Symbol	Example	Cldr Format
Era	G, GG, GGG	"AD"	Abbreviated
	GGGG	"Anno Domini"	Wide
	GGGGG	"A"	Narrow
Year	y	7	Minimum necessary digits
	yy	"17"	Least significant 2 digits
	yyy	"017", "2017"	Padded to at least 3 digits
	yyyy	"2017"	Padded to at least 4 digits
	yyyyy	"02017"	Padded to at least 5 digits
ISOWeek Year	Y	7	Minimum necessary digits
	YY	"17"	Least significant 2 digits
	YYY	"017", "2017"	Padded to at least 3 digits
	YYYY	"2017"	Padded to at least 4 digits
	YYYYY	"02017"	Padded to at least 5 digits
Related Gregorian Year	r, rr, rr+	2017	Minimum necessary digits
Cyclic Year	U, UU, UUU	"甲子"	Abbreviated
	UUUU	"甲子" (for now)	Wide
	UUUUU	"甲子" (for now)	Narrow
Extended Year	u+	4601	Minimum necessary digits
Quarter	Q	2	Single digit
	QQ	"02"	Two digits
	QQQ	"Q2"	Abbreviated
	QQQQ	"2nd quarter"	Wide
	QQQQQ	"2"	Narrow
Standalone Quarter	q	2	Single digit
	qq	"02"	Two digits
	qqq	"Q2"	Abbreviated
	qqqq	"2nd quarter"	Wide
	qqqqq	"2"	Narrow
Month	M	9	Single digit
	MM	"09"	Two digits
	MMM	"Sep"	Abbreviated
	MMMM	"September"	Wide
	MMMMM	"S"	Narrow
Standalone Month	L	9	Single digit
	LL	"09"	Two digits
	LLL	"Sep"	Abbreviated
	LLLL	"September"	Wide
	LLLLL	"S"	Narrow
Week of Year	w	2, 22	Single digit
	ww	02, 22	Two digits, zero padded
Week of Month	W	2	Single digit. NOT IMPLEMENTED YET
Day of Year	D	3, 33, 333	Minimum necessary digits
	DD	03, 33, 333	Minimum of 2 digits, zero padded
	DDD	003, 033, 333	Minimum of 3 digits, zero padded
Day of Month	d	2, 22	Minimum necessary digits
	dd	02, 22	Two digits, zero padded
Day of Week	E, EE, EEE	"Tue"	Abbreviated
	EEEE	"Tuesday"	Wide
	EEEEE	"T"	Narrow
	EEEEEE	"Tu"	Short
	e	2	Single digit
	ee	"02"	Two digits
	eee	"Tue"	Abbreviated
	eeee	"Tuesday"	Wide
	eeeee	"T"	Narrow
	eeeeee	"Tu"	Short
Standalone Day of Week	c, cc	2	Single digit
	ccc	"Tue"	Abbreviated
	cccc	"Tuesday"	Wide
	ccccc	"T"	Narrow
	cccccc	"Tu"	Short
AM or PM	a, aa, aaa	"am."	Abbreviated
	aaaa	"am."	Wide
	aaaaa	"am"	Narrow
Noon, Mid, AM, PM	b, bb, bbb	"mid."	Abbreviated
	bbbb	"midnight"	Wide
	bbbbb	"md"	Narrow
Flexible time period	B, BB, BBB	"at night"	Abbreviated
	BBBB	"at night"	Wide
	BBBBB	"at night"	Narrow
Hour	h, K, H, k		See the table below
Minute	m	3, 10	Minimum digits of minutes
	mm	"03", "12"	Two digits, zero padded
Second	s	3, 48	Minimum digits of seconds
	ss	"03", "48"	Two digits, zero padded
Fractional Seconds	S	3, 48	Minimum digits of fractional seconds
	SS	"03", "48"	Two digits, zero padded
Milliseconds	A+	4000, 63241	Minimum digits of milliseconds since midnight
Generic non-location TZ	v	"Etc/UTC"	:time_zone key, unlocalised
	vvvv	"unk"	Generic timezone name. Currently returns only "unk"
Specific non-location TZ	z..zzz	"UTC"	:zone_abbr key, unlocalised
	zzzz	"GMT"	Delegates to zone_gmt/4
Timezone ID	V	"unk"	:zone_abbr key, unlocalised
	VV	"Etc/UTC	Delegates to zone_gmt/4
	VVV	"Unknown City"	Exemplar city. Not supported.
	VVVV	"GMT"	Delegates to `zone_gmt/4
ISO8601 Format	Z..ZZZ	"+0100"	ISO8601 Basic Format with hours and minutes
	ZZZZ	"+01:00"	Delegates to `zone_gmt/4
	ZZZZZ	"+01:00:10"	ISO8601 Extended format with optional seconds
ISO8601 plus Z	X	"+01"	ISO8601 Basic Format with hours and optional minutes or "Z"
	XX	"+0100"	ISO8601 Basic Format with hours and minutes or "Z"
	XXX	"+0100"	ISO8601 Basic Format with hours and minutes, optional seconds or "Z"
	XXXX	"+010059"	ISO8601 Basic Format with hours and minutes, optional seconds or "Z"
	XXXXX	"+01:00:10"	ISO8601 Extended Format with hours and minutes, optional seconds or "Z"
ISO8601 minus Z	x	"+0100"	ISO8601 Basic Format with hours and optional minutes
	xx	"-0800"	ISO8601 Basic Format with hours and minutes
	xxx	"+01:00"	ISO8601 Extended Format with hours and minutes
	xxxx	"+010059"	ISO8601 Basic Format with hours and minutes, optional seconds
	xxxxx	"+01:00:10"	ISO8601 Extended Format with hours and minutes, optional seconds
GMT Format	O	"+0100"	Short localised GMT format
	OOOO	"+010059"	Long localised GMT format

Formatting symbols for hour of day

The hour of day can be formatted differently depending whether a 12- or 24-hour day is being represented and depending on the way in which midnight and noon are represented. The following table illustrates the differences:

Symbol	Midn.	Morning	Noon	Afternoon	Midn.
h	12	1...11	12	1...11	12
K	0	1...11	0	1...11	0
H	0	1...11	12	13...23	0
k	24	1...11	12	13...23	24

Relative Date, Time and DateTime Localization Formatting

The primary API for formatting relative dates and datetimes is MyApp.Cldr.DateTime.Relative.to_string/2. Some examples:

iex> MyApp.Cldr.DateTime.Relative.to_string(-1)
{:ok, "1 second ago"}

iex> MyApp.Cldr.DateTime.Relative.to_string(1)
{:ok, "in 1 second"}

iex> MyApp.Cldr.DateTime.Relative.to_string(1, unit: :day)
{:ok, "tomorrow"}

iex> MyApp.Cldr.DateTime.Relative.to_string(1, unit: :day, locale: "fr")
{:ok, "demain"}

iex> MyApp.Cldr.DateTime.Relative.to_string(1, unit: :day, format: :narrow)
{:ok, "tomorrow"}

iex> MyApp.Cldr.DateTime.Relative.to_string(1234, unit: :year)
{:ok, "in 1,234 years"}

iex> MyApp.Cldr.DateTime.Relative.to_string(1234, unit: :year, locale: "fr")
{:ok, "dans 1 234 ans"}

iex> MyApp.Cldr.DateTime.Relative.to_string(31)
{:ok, "in 31 seconds"}

iex> MyApp.Cldr.DateTime.Relative.to_string(~D[2017-04-29], relative_to: ~D[2017-04-26])
{:ok, "in 3 days"}

iex> MyApp.Cldr.DateTime.Relative.to_string(310, format: :short, locale: "fr")
{:ok, "dans 5 min"}

iex> MyApp.Cldr.DateTime.Relative.to_string(310, format: :narrow, locale: "fr")
{:ok, "+5 min"}

iex> MyApp.Cldr.DateTime.Relative.to_string 2, unit: :wed, format: :short
{:ok, "in 2 Wed."}

iex> MyApp.Cldr.DateTime.Relative.to_string 1, unit: :wed, format: :short
{:ok, "next Wed."}

iex> MyApp.Cldr.DateTime.Relative.to_string -1, unit: :wed, format: :short
{:ok, "last Wed."}

iex> MyApp.Cldr.DateTime.Relative.to_string -1, unit: :wed
{:ok, "last Wednesday"}

iex> MyApp.Cldr.DateTime.Relative.to_string -1, unit: :quarter
{:ok, "last quarter"}

iex> MyApp.Cldr.DateTime.Relative.to_string -1, unit: :mon, locale: "fr"
{:ok, "lundi dernier"}

iex> MyApp.Cldr.DateTime.Relative.to_string(~D[2017-04-29], unit: :ziggeraut)
{:error, {Cldr.UnknownTimeUnit,
"Unknown time unit :ziggeraut.  Valid time units are [:day, :hour, :minute, :month, :second, :week, :year, :mon, :tue, :wed, :thu, :fri, :sat, :sun, :quarter]"}}

Interval Formatting

Interval formats allow for software to format intervals like "Jan 10-12, 2008" as a shorter and more natural format than "Jan 10, 2008 - Jan 12, 2008". They are designed to take a start and end date, time or datetime plus a formatting pattern and use that information to produce a localized format.

An interval is expressed as either a from and to date, time or datetime. Or it can also be a Date.Range or CalendarInterval from the calendar_interval library.

Cldr.Interval.to_string/3 function to format an interval based upon the type of the arguments: date, datetime or time. The modules Cldr.Date.Interval, Cldr.Time.Interval and Cldr.DateTime.Interval also provide a to_string/3 function for when the desired output format is more specific.

Some examples:

iex> Cldr.Interval.to_string ~D[2020-01-01], ~D[2020-12-31], MyApp.Cldr
{:ok, "Jan 1 – Dec 31, 2020"}

iex> Cldr.Interval.to_string ~D[2020-01-01], ~D[2020-01-12], MyApp.Cldr
{:ok, "Jan 1 – 12, 2020"}

iex> Cldr.Interval.to_string ~D[2020-01-01], ~D[2020-01-12], MyApp.Cldr,
...> format: :long
{:ok, "Wed, Jan 1 – Sun, Jan 12, 2020"}

iex> Cldr.Interval.to_string ~D[2020-01-01], ~D[2020-12-01], MyApp.Cldr,
...> format: :long, style: :year_and_month
{:ok, "January – December 2020"}

iex> use CalendarInterval
iex> Cldr.Interval.to_string ~I"2020-01-01/12", MyApp.Cldr,
...> format: :long
{:ok, "Wed, Jan 1 – Sun, Jan 12, 2020"}

iex> Cldr.Interval.to_string ~U[2020-01-01 00:00:00.0Z], ~U[2020-12-01 10:05:00.0Z], MyApp.Cldr,
...> format: :long
{:ok, "January 1, 2020 at 12:00:00 AM UTC – December 1, 2020 at 10:05:00 AM UTC"}

iex> Cldr.Interval.to_string ~U[2020-01-01 00:00:00.0Z], ~U[2020-01-01 10:05:00.0Z], MyApp.Cldr,
...> format: :long
{:ok, "January 1, 2020 at 12:00:00 AM UTC – 10:05:00 AM UTC"}

Known restrictions and limitations

Although largely complete (with respect to the CLDR data), there are some known limitations as of release 2.0.

• Timezones Although the timezone format codes are supported (formatting symbols v, V, x, X, z, Z, O) not all localisations are performed. Only that data available within a t:DateTime.t/0 struct is used to format timezone data.