Elixir v1.8.1 NaiveDateTime View Source

A NaiveDateTime struct (without a time zone) and functions.

The NaiveDateTime struct contains the fields year, month, day, hour, minute, second, microsecond and calendar. New naive datetimes can be built with the new/2 and new/8 functions or using the ~N (see Kernel.sigil_N/2) sigil:

iex> ~N[2000-01-01 23:00:07]
~N[2000-01-01 23:00:07]

The date and time fields in the struct can be accessed directly:

iex> naive = ~N[2000-01-01 23:00:07]
iex> naive.year
2000
iex> naive.second
7

We call them "naive" because this datetime representation does not have a time zone. This means the datetime may not actually exist in certain areas in the world even though it is valid.

For example, when daylight saving changes are applied by a region, the clock typically moves forward or backward by one hour. This means certain datetimes never occur or may occur more than once. Since NaiveDateTime is not validated against a time zone, such errors would go unnoticed.

Developers should avoid creating the NaiveDateTime structs directly and instead, rely on the functions provided by this module as well as the ones in third-party calendar libraries.

Comparing naive date times

Comparisons in Elixir using ==/2, >/2, </2 and similar are structural and based on the NaiveDateTime struct fields. For proper comparison between naive datetimes, use the compare/2 function.

Using epochs

The add/3 and diff/3 functions can be used for computing with date times or retrieving the number of seconds between instants. For example, if there is an interest in computing the number of seconds from the Unix epoch (1970-01-01 00:00:00):

iex> NaiveDateTime.diff(~N[2010-04-17 14:00:00], ~N[1970-01-01 00:00:00])
1271512800

iex> NaiveDateTime.add(~N[1970-01-01 00:00:00], 1_271_512_800)
~N[2010-04-17 14:00:00]

Those functions are optimized to deal with common epochs, such as the Unix Epoch above or the Gregorian Epoch (0000-01-01 00:00:00).

Link to this section Summary

Functions

Converts the given naive_datetime from one calendar to another

Converts the given naive_datetime from one calendar to another

Subtracts naive_datetime2 from naive_datetime1

Parses the extended "Date and time of day" format described by ISO 8601:2004

Parses the extended "Date and time of day" format described by ISO 8601:2004

Builds a naive datetime from date and time structs

Converts a NaiveDateTime into a Date

Converts a NaiveDateTime struct to an Erlang datetime tuple

Converts the given naive datetime to ISO 8601:2004

Converts the given naive datetime to a string according to its calendar

Returns the given naive datetime with the microsecond field truncated to the given precision (:microsecond, :millisecond or :second)

Returns the current naive datetime in UTC

Link to this section Types

Link to this type

t() View Source
t() :: %NaiveDateTime{
  calendar: Calendar.calendar(),
  day: Calendar.day(),
  hour: Calendar.hour(),
  microsecond: Calendar.microsecond(),
  minute: Calendar.minute(),
  month: Calendar.month(),
  second: Calendar.second(),
  year: Calendar.year()
}

Link to this section Functions

Link to this function

add(naive_datetime, amount_to_add, unit \\ :second) View Source (since 1.4.0)

Adds a specified amount of time to a NaiveDateTime.

Accepts an amount_to_add in any unit available from System.time_unit/0. Negative values will move backwards in time.

Examples

# adds seconds by default
iex> NaiveDateTime.add(~N[2014-10-02 00:29:10], 2)
~N[2014-10-02 00:29:12]

# accepts negative offsets
iex> NaiveDateTime.add(~N[2014-10-02 00:29:10], -2)
~N[2014-10-02 00:29:08]

# can work with other units
iex> NaiveDateTime.add(~N[2014-10-02 00:29:10], 2_000, :millisecond)
~N[2014-10-02 00:29:12]

# keeps the same precision
iex> NaiveDateTime.add(~N[2014-10-02 00:29:10.021], 21, :second)
~N[2014-10-02 00:29:31.021]

# changes below the precision will not be visible
iex> hidden = NaiveDateTime.add(~N[2014-10-02 00:29:10], 21, :millisecond)
iex> hidden.microsecond # ~N[2014-10-02 00:29:10]
{21000, 0}

# from Gregorian seconds
iex> NaiveDateTime.add(~N[0000-01-01 00:00:00], 63_579_428_950)
~N[2014-10-02 00:29:10]

Passing a Datetime automatically converts it to NaiveDateTime, discarding the time zone information:

iex> dt = %DateTime{year: 2000, month: 2, day: 29, zone_abbr: "CET",
...>                hour: 23, minute: 0, second: 7, microsecond: {0, 0},
...>                utc_offset: 3600, std_offset: 0, time_zone: "Europe/Warsaw"}
iex> NaiveDateTime.add(dt, 21, :second)
~N[2000-02-29 23:00:28]
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compare(naive_datetime1, naive_datetime2) View Source (since 1.4.0)
compare(Calendar.naive_datetime(), Calendar.naive_datetime()) :: :lt | :eq | :gt

Compares two NaiveDateTime structs.

Returns :gt if first is later than the second and :lt for vice versa. If the two NaiveDateTime are equal :eq is returned.

Examples

iex> NaiveDateTime.compare(~N[2016-04-16 13:30:15], ~N[2016-04-28 16:19:25])
:lt
iex> NaiveDateTime.compare(~N[2016-04-16 13:30:15.1], ~N[2016-04-16 13:30:15.01])
:gt

This function can also be used to compare a DateTime without the time zone information:

iex> dt = %DateTime{year: 2000, month: 2, day: 29, zone_abbr: "CET",
...>                hour: 23, minute: 0, second: 7, microsecond: {0, 0},
...>                utc_offset: 3600, std_offset: 0, time_zone: "Europe/Warsaw"}
iex> NaiveDateTime.compare(dt, ~N[2000-02-29 23:00:07])
:eq
iex> NaiveDateTime.compare(dt, ~N[2000-01-29 23:00:07])
:gt
iex> NaiveDateTime.compare(dt, ~N[2000-03-29 23:00:07])
:lt
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convert(naive_datetime, calendar) View Source (since 1.5.0)
convert(Calendar.naive_datetime(), Calendar.calendar()) ::
  {:ok, t()} | {:error, :incompatible_calendars}

Converts the given naive_datetime from one calendar to another.

If it is not possible to convert unambiguously between the calendars (see Calendar.compatible_calendars?/2), an {:error, :incompatible_calendars} tuple is returned.

Examples

Imagine someone implements Calendar.Holocene, a calendar based on the Gregorian calendar that adds exactly 10,000 years to the current Gregorian year:

iex> NaiveDateTime.convert(~N[2000-01-01 13:30:15], Calendar.Holocene)
{:ok, %NaiveDateTime{calendar: Calendar.Holocene, year: 12000, month: 1, day: 1,
                     hour: 13, minute: 30, second: 15, microsecond: {0, 0}}}
Link to this function

convert!(naive_datetime, calendar) View Source (since 1.5.0)

Converts the given naive_datetime from one calendar to another.

If it is not possible to convert unambiguously between the calendars (see Calendar.compatible_calendars?/2), an ArgumentError is raised.

Examples

Imagine someone implements Calendar.Holocene, a calendar based on the Gregorian calendar that adds exactly 10,000 years to the current Gregorian year:

iex> NaiveDateTime.convert!(~N[2000-01-01 13:30:15], Calendar.Holocene)
%NaiveDateTime{calendar: Calendar.Holocene, year: 12000, month: 1, day: 1,
               hour: 13, minute: 30, second: 15, microsecond: {0, 0}}
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diff(naive_datetime1, naive_datetime2, unit \\ :second) View Source (since 1.4.0)

Subtracts naive_datetime2 from naive_datetime1.

The answer can be returned in any unit available from System.time_unit/0.

This function returns the difference in seconds where seconds are measured according to Calendar.ISO.

Examples

iex> NaiveDateTime.diff(~N[2014-10-02 00:29:12], ~N[2014-10-02 00:29:10])
2
iex> NaiveDateTime.diff(~N[2014-10-02 00:29:12], ~N[2014-10-02 00:29:10], :microsecond)
2_000_000
iex> NaiveDateTime.diff(~N[2014-10-02 00:29:10.042], ~N[2014-10-02 00:29:10.021], :millisecond)
21
iex> NaiveDateTime.diff(~N[2014-10-02 00:29:10], ~N[2014-10-02 00:29:12])
-2
iex> NaiveDateTime.diff(~N[-0001-10-02 00:29:10], ~N[-0001-10-02 00:29:12])
-2

# to Gregorian seconds
iex> NaiveDateTime.diff(~N[2014-10-02 00:29:10], ~N[0000-01-01 00:00:00])
63579428950
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from_erl(tuple, microsecond \\ {0, 0}, calendar \\ Calendar.ISO) View Source
from_erl(:calendar.datetime(), Calendar.microsecond(), Calendar.calendar()) ::
  {:ok, t()} | {:error, atom()}

Converts an Erlang datetime tuple to a NaiveDateTime struct.

Attempting to convert an invalid ISO calendar date will produce an error tuple.

Examples

iex> NaiveDateTime.from_erl({{2000, 1, 1}, {13, 30, 15}})
{:ok, ~N[2000-01-01 13:30:15]}
iex> NaiveDateTime.from_erl({{2000, 1, 1}, {13, 30, 15}}, {5000, 3})
{:ok, ~N[2000-01-01 13:30:15.005]}
iex> NaiveDateTime.from_erl({{2000, 13, 1}, {13, 30, 15}})
{:error, :invalid_date}
iex> NaiveDateTime.from_erl({{2000, 13, 1}, {13, 30, 15}})
{:error, :invalid_date}
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from_erl!(tuple, microsecond \\ {0, 0}, calendar \\ Calendar.ISO) View Source

Converts an Erlang datetime tuple to a NaiveDateTime struct.

Raises if the datetime is invalid. Attempting to convert an invalid ISO calendar date will produce an error tuple.

Examples

iex> NaiveDateTime.from_erl!({{2000, 1, 1}, {13, 30, 15}})
~N[2000-01-01 13:30:15]
iex> NaiveDateTime.from_erl!({{2000, 1, 1}, {13, 30, 15}}, {5000, 3})
~N[2000-01-01 13:30:15.005]
iex> NaiveDateTime.from_erl!({{2000, 13, 1}, {13, 30, 15}})
** (ArgumentError) cannot convert {{2000, 13, 1}, {13, 30, 15}} to naive datetime, reason: :invalid_date
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from_iso8601(string, calendar \\ Calendar.ISO) View Source
from_iso8601(String.t(), Calendar.calendar()) ::
  {:ok, t()} | {:error, atom()}

Parses the extended "Date and time of day" format described by ISO 8601:2004.

Time zone offset may be included in the string but they will be simply discarded as such information is not included in naive date times.

As specified in the standard, the separator "T" may be omitted if desired as there is no ambiguity within this function.

The year parsed by this function is limited to four digits and, while ISO 8601 allows datetimes to specify 24:00:00 as the zero hour of the next day, this notation is not supported by Elixir. Note leap seconds are not supported by the built-in Calendar.ISO.

Examples

iex> NaiveDateTime.from_iso8601("2015-01-23 23:50:07")
{:ok, ~N[2015-01-23 23:50:07]}
iex> NaiveDateTime.from_iso8601("2015-01-23T23:50:07")
{:ok, ~N[2015-01-23 23:50:07]}
iex> NaiveDateTime.from_iso8601("2015-01-23T23:50:07Z")
{:ok, ~N[2015-01-23 23:50:07]}

iex> NaiveDateTime.from_iso8601("2015-01-23 23:50:07.0")
{:ok, ~N[2015-01-23 23:50:07.0]}
iex> NaiveDateTime.from_iso8601("2015-01-23 23:50:07,0123456")
{:ok, ~N[2015-01-23 23:50:07.012345]}
iex> NaiveDateTime.from_iso8601("2015-01-23 23:50:07.0123456")
{:ok, ~N[2015-01-23 23:50:07.012345]}
iex> NaiveDateTime.from_iso8601("2015-01-23T23:50:07.123Z")
{:ok, ~N[2015-01-23 23:50:07.123]}

iex> NaiveDateTime.from_iso8601("2015-01-23P23:50:07")
{:error, :invalid_format}
iex> NaiveDateTime.from_iso8601("2015:01:23 23-50-07")
{:error, :invalid_format}
iex> NaiveDateTime.from_iso8601("2015-01-23 23:50:07A")
{:error, :invalid_format}
iex> NaiveDateTime.from_iso8601("2015-01-23 23:50:61")
{:error, :invalid_time}
iex> NaiveDateTime.from_iso8601("2015-01-32 23:50:07")
{:error, :invalid_date}

iex> NaiveDateTime.from_iso8601("2015-01-23T23:50:07.123+02:30")
{:ok, ~N[2015-01-23 23:50:07.123]}
iex> NaiveDateTime.from_iso8601("2015-01-23T23:50:07.123+00:00")
{:ok, ~N[2015-01-23 23:50:07.123]}
iex> NaiveDateTime.from_iso8601("2015-01-23T23:50:07.123-02:30")
{:ok, ~N[2015-01-23 23:50:07.123]}
iex> NaiveDateTime.from_iso8601("2015-01-23T23:50:07.123-00:00")
{:error, :invalid_format}
iex> NaiveDateTime.from_iso8601("2015-01-23T23:50:07.123-00:60")
{:error, :invalid_format}
iex> NaiveDateTime.from_iso8601("2015-01-23T23:50:07.123-24:00")
{:error, :invalid_format}
Link to this function

from_iso8601!(string, calendar \\ Calendar.ISO) View Source
from_iso8601!(String.t(), Calendar.calendar()) :: t()

Parses the extended "Date and time of day" format described by ISO 8601:2004.

Raises if the format is invalid.

Examples

iex> NaiveDateTime.from_iso8601!("2015-01-23T23:50:07.123Z")
~N[2015-01-23 23:50:07.123]
iex> NaiveDateTime.from_iso8601!("2015-01-23T23:50:07,123Z")
~N[2015-01-23 23:50:07.123]
iex> NaiveDateTime.from_iso8601!("2015-01-23P23:50:07")
** (ArgumentError) cannot parse "2015-01-23P23:50:07" as naive datetime, reason: :invalid_format
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new(date, time) View Source
new(Date.t(), Time.t()) :: {:ok, t()}

Builds a naive datetime from date and time structs.

Examples

iex> NaiveDateTime.new(~D[2010-01-13], ~T[23:00:07.005])
{:ok, ~N[2010-01-13 23:00:07.005]}
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new(year, month, day, hour, minute, second, microsecond \\ {0, 0}, calendar \\ Calendar.ISO) View Source

Builds a new ISO naive datetime.

Expects all values to be integers. Returns {:ok, naive_datetime} if each entry fits its appropriate range, returns {:error, reason} otherwise.

Examples

iex> NaiveDateTime.new(2000, 1, 1, 0, 0, 0)
{:ok, ~N[2000-01-01 00:00:00]}
iex> NaiveDateTime.new(2000, 13, 1, 0, 0, 0)
{:error, :invalid_date}
iex> NaiveDateTime.new(2000, 2, 29, 0, 0, 0)
{:ok, ~N[2000-02-29 00:00:00]}
iex> NaiveDateTime.new(2000, 2, 30, 0, 0, 0)
{:error, :invalid_date}
iex> NaiveDateTime.new(2001, 2, 29, 0, 0, 0)
{:error, :invalid_date}

iex> NaiveDateTime.new(2000, 1, 1, 23, 59, 59, {0, 1})
{:ok, ~N[2000-01-01 23:59:59.0]}
iex> NaiveDateTime.new(2000, 1, 1, 23, 59, 59, 999_999)
{:ok, ~N[2000-01-01 23:59:59.999999]}
iex> NaiveDateTime.new(2000, 1, 1, 24, 59, 59, 999_999)
{:error, :invalid_time}
iex> NaiveDateTime.new(2000, 1, 1, 23, 60, 59, 999_999)
{:error, :invalid_time}
iex> NaiveDateTime.new(2000, 1, 1, 23, 59, 60, 999_999)
{:error, :invalid_time}
iex> NaiveDateTime.new(2000, 1, 1, 23, 59, 59, 1_000_000)
{:error, :invalid_time}

iex> NaiveDateTime.new(2000, 1, 1, 23, 59, 59, {0, 1}, Calendar.ISO)
{:ok, ~N[2000-01-01 23:59:59.0]}

Converts a NaiveDateTime into a Date.

Because Date does not hold time information, data will be lost during the conversion.

Examples

iex> NaiveDateTime.to_date(~N[2002-01-13 23:00:07])
~D[2002-01-13]

Converts a NaiveDateTime struct to an Erlang datetime tuple.

Only supports converting naive datetimes which are in the ISO calendar, attempting to convert naive datetimes from other calendars will raise.

WARNING: Loss of precision may occur, as Erlang time tuples only store hour/minute/second.

Examples

iex> NaiveDateTime.to_erl(~N[2000-01-01 13:30:15])
{{2000, 1, 1}, {13, 30, 15}}

This function can also be used to convert a DateTime to a erl format without the time zone information:

iex> dt = %DateTime{year: 2000, month: 2, day: 29, zone_abbr: "CET",
...>                hour: 23, minute: 0, second: 7, microsecond: {0, 0},
...>                utc_offset: 3600, std_offset: 0, time_zone: "Europe/Warsaw"}
iex> NaiveDateTime.to_erl(dt)
{{2000, 2, 29}, {23, 00, 07}}
Link to this function

to_iso8601(naive_datetime, format \\ :extended) View Source
to_iso8601(Calendar.naive_datetime(), :basic | :extended) :: String.t()

Converts the given naive datetime to ISO 8601:2004.

By default, NaiveDateTime.to_iso8601/2 returns naive datetimes formatted in the "extended" format, for human readability. It also supports the "basic" format through passing the :basic option.

Only supports converting naive datetimes which are in the ISO calendar, attempting to convert naive datetimes from other calendars will raise.

Examples

iex> NaiveDateTime.to_iso8601(~N[2000-02-28 23:00:13])
"2000-02-28T23:00:13"

iex> NaiveDateTime.to_iso8601(~N[2000-02-28 23:00:13.001])
"2000-02-28T23:00:13.001"

iex> NaiveDateTime.to_iso8601(~N[2000-02-28 23:00:13.001], :basic)
"20000228T230013.001"

This function can also be used to convert a DateTime to ISO 8601 without the time zone information:

iex> dt = %DateTime{year: 2000, month: 2, day: 29, zone_abbr: "CET",
...>                hour: 23, minute: 0, second: 7, microsecond: {0, 0},
...>                utc_offset: 3600, std_offset: 0, time_zone: "Europe/Warsaw"}
iex> NaiveDateTime.to_iso8601(dt)
"2000-02-29T23:00:07"
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to_string(naive_datetime) View Source
to_string(Calendar.naive_datetime()) :: String.t()

Converts the given naive datetime to a string according to its calendar.

Examples

iex> NaiveDateTime.to_string(~N[2000-02-28 23:00:13])
"2000-02-28 23:00:13"
iex> NaiveDateTime.to_string(~N[2000-02-28 23:00:13.001])
"2000-02-28 23:00:13.001"
iex> NaiveDateTime.to_string(~N[-0100-12-15 03:20:31])
"-0100-12-15 03:20:31"

This function can also be used to convert a DateTime to a string without the time zone information:

iex> dt = %DateTime{year: 2000, month: 2, day: 29, zone_abbr: "CET",
...>                hour: 23, minute: 0, second: 7, microsecond: {0, 0},
...>                utc_offset: 3600, std_offset: 0, time_zone: "Europe/Warsaw"}
iex> NaiveDateTime.to_string(dt)
"2000-02-29 23:00:07"

Converts a NaiveDateTime into Time.

Because Time does not hold date information, data will be lost during the conversion.

Examples

iex> NaiveDateTime.to_time(~N[2002-01-13 23:00:07])
~T[23:00:07]
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truncate(naive_datetime, precision) View Source (since 1.6.0)
truncate(t(), :microsecond | :millisecond | :second) :: t()

Returns the given naive datetime with the microsecond field truncated to the given precision (:microsecond, :millisecond or :second).

The given naive datetime is returned unchanged if it already has lower precision than the given precision.

Examples

iex> NaiveDateTime.truncate(~N[2017-11-06 00:23:51.123456], :microsecond)
~N[2017-11-06 00:23:51.123456]

iex> NaiveDateTime.truncate(~N[2017-11-06 00:23:51.123456], :millisecond)
~N[2017-11-06 00:23:51.123]

iex> NaiveDateTime.truncate(~N[2017-11-06 00:23:51.123456], :second)
~N[2017-11-06 00:23:51]
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utc_now(calendar \\ Calendar.ISO) View Source (since 1.4.0)
utc_now(Calendar.calendar()) :: t()

Returns the current naive datetime in UTC.

Prefer using DateTime.utc_now/0 when possible as, opposite to NaiveDateTime, it will keep the time zone information.

Examples

iex> naive_datetime = NaiveDateTime.utc_now()
iex> naive_datetime.year >= 2016
true