Calendar.Date
The Date module provides a struct to represent a simple date: year, month and day.
Summary↑
| advance!(date, days) | Like |
| advance(date, days) | Advances |
| days_after(from_date) | Stream of dates after the date provided as argument |
| days_after_until(from_date, until_date) | Get a stream of dates. Takes a starting date and an end date. Includes end date. Does not include start date |
| days_before(from_date) | Stream of dates before the date provided as argument |
| days_before_until(from_date, until_date) | Get a stream of dates going back in time. Takes a starting date and an end date. Includes end date. End date should be before start date. Does not include start date |
| diff(first_date, second_date) | Difference in days between two dates |
| from_erl!(erl_date) | Like from_erl without the exclamation point, but does not return a tuple with a tag. Instead returns just a Date if valid. Or raises an exception if the provided date is invalid |
| from_erl(arg1) | Takes a erlang style date tuple and returns a tuple with an :ok tag and a Date struct. If the provided date is invalid, it will not be tagged with :ok though as shown below: |
| next_day!(date) | Takes a Date struct and returns another one representing the next day |
| number_of_days_in_month(date) | Takes a Date struct and returns the number of days in the month of that date. The day of the date provided does not matter - the result is based on the month and the year |
| prev_day!(date) | Takes a Date struct and returns another one representing the previous day |
| strftime!(date, string, lang \\ :en) | Format date as string |
| to_erl(date) | Takes a Date struct and returns an erlang style date tuple |
| to_gregorian_days(date) | Takes a Date struct and returns the number of gregorian days since year 0 |
| week_number(date) | Takes a Date struct and returns a tuple with the ISO week number and the year that the week belongs to. Note that the year returned does not always match the year provided |
Functions
Advances date by days number of days.
Examples
iex> from_erl!({2014,12,27}) |> advance(3)
{:ok, %Calendar.Date{day: 30, month: 12, year: 2014} }
iex> from_erl!({2014,12,27}) |> advance(-2)
{:ok, %Calendar.Date{day: 25, month: 12, year: 2014} }Like advance/2, but returns the result directly - not tagged with :ok. This function might raise an error.
Examples
iex> from_erl!({2014,12,27}) |> advance!(3)
%Calendar.Date{day: 30, month: 12, year: 2014}Stream of dates after the date provided as argument.
iex> days_after(from_erl!({2014,12,27})) |> Enum.take(6)
[%Calendar.Date{day: 28, month: 12, year: 2014}, %Calendar.Date{day: 29, month: 12, year: 2014},
%Calendar.Date{day: 30, month: 12, year: 2014}, %Calendar.Date{day: 31, month: 12, year: 2014}, %Calendar.Date{day: 1, month: 1, year: 2015},
%Calendar.Date{day: 2, month: 1, year: 2015}]Get a stream of dates. Takes a starting date and an end date. Includes end date. Does not include start date.
iex> days_after_until(from_erl!({2014,12,27}), from_erl!({2014,12,29})) |> Enum.to_list
[%Calendar.Date{day: 28, month: 12, year: 2014}, %Calendar.Date{day: 29, month: 12, year: 2014}]Stream of dates before the date provided as argument.
iex> days_before(from_erl!({2014,12,27})) |> Enum.take(3)
[%Calendar.Date{day: 26, month: 12, year: 2014}, %Calendar.Date{day: 25, month: 12, year: 2014},
%Calendar.Date{day: 24, month: 12, year: 2014}]Get a stream of dates going back in time. Takes a starting date and an end date. Includes end date. End date should be before start date. Does not include start date.
iex> days_before_until(from_erl!({2014,12,27}), from_erl!({2014,12,24})) |> Enum.to_list
[%Calendar.Date{day: 26, month: 12, year: 2014}, %Calendar.Date{day: 25, month: 12, year: 2014}, %Calendar.Date{day: 24, month: 12, year: 2014}]Difference in days between two dates.
Takes two Date structs: first_date and second_date. Subtracts second_date from first_date.
iex> from_erl!({2014,12,27}) |> diff from_erl!({2014,12,20})
7
iex> from_erl!({2014,12,27}) |> diff from_erl!({2014,12,29})
-2Takes a erlang style date tuple and returns a tuple with an :ok tag and a Date struct. If the provided date is invalid, it will not be tagged with :ok though as shown below:
iex> from_erl({2014,12,27})
{:ok, %Calendar.Date{day: 27, month: 12, year: 2014}}
iex> from_erl({2014,99,99})
{:error, :invalid_date}Like from_erl without the exclamation point, but does not return a tuple with a tag. Instead returns just a Date if valid. Or raises an exception if the provided date is invalid.
iex> from_erl! {2014,12,27}
%Calendar.Date{day: 27, month: 12, year: 2014}Takes a Date struct and returns another one representing the next day.
iex> from_erl!({2014,12,27}) |> next_day!
%Calendar.Date{day: 28, month: 12, year: 2014}
iex> from_erl!({2014,12,31}) |> next_day!
%Calendar.Date{day: 1, month: 1, year: 2015}Takes a Date struct and returns the number of days in the month of that date. The day of the date provided does not matter - the result is based on the month and the year.
iex> from_erl!({2014,12,27}) |> number_of_days_in_month
31
iex> from_erl!({2015,2,27}) |> number_of_days_in_month
28
iex> from_erl!({2012,2,27}) |> number_of_days_in_month
29Takes a Date struct and returns another one representing the previous day.
iex> from_erl!({2014,12,27}) |> prev_day!
%Calendar.Date{day: 26, month: 12, year: 2014}Format date as string.
Takes
date- a Date structstring- formatting stringlang(optional) - language code
Examples
iex> strftime!(from_erl!({2014,12,27}), "%Y-%m-%d")
"2014-12-27"Takes a Date struct and returns an erlang style date tuple.
Takes a Date struct and returns the number of gregorian days since year 0.
iex> from_erl!({2014,12,27}) |> to_gregorian_days
735959Takes a Date struct and returns a tuple with the ISO week number and the year that the week belongs to. Note that the year returned does not always match the year provided.
iex> from_erl!({2014,12,31}) |> week_number
{2015, 1}
iex> from_erl!({2014,12,27}) |> week_number
{2014, 52}