Generate a string from a DateTime, NaiveDateTime, Time or Date formatted by a format string. Similar to strftime known from Unix systems.

Examples

iex> {{2014,9,6},{17,10,20}} |> Calendar.NaiveDateTime.from_erl! |> strftime("%A %Y-%m-%e %H:%M:%S")
{:ok, "Saturday 2014-09- 6 17:10:20"}

# Passing erlang style naive date time tuple directly
iex> {{2014,9,6},{17,10,20}} |> strftime("%A %Y-%m-%e %H:%M:%S")
{:ok, "Saturday 2014-09- 6 17:10:20"}

iex> Calendar.DateTime.from_erl!({{2014,9,6},{17,10,20}},"Etc/UTC") |> strftime("%A %Y-%m-%e %H:%M:%S")
{:ok, "Saturday 2014-09- 6 17:10:20"}

iex> Calendar.DateTime.from_erl!({{2014,9,6},{17,10,20}},"Etc/UTC") |> strftime("%a %d.%m.%y")
{:ok, "Sat 06.09.14"}

# Passing a Date struct
iex> Calendar.Date.from_erl!({2014,9,6}) |> strftime("%a %d.%m.%y")
{:ok, "Sat 06.09.14"}

# Trying to use date conversion specs and passing a Time struct results in errors
iex> Calendar.Time.from_erl!({12, 30, 59}) |> strftime("%a %d.%m.%y")
{:error, :missing_data_for_conversion_spec}

# Passing a Time and using just conversion specs suitable for time
iex> Calendar.Time.from_erl!({12, 30, 59}) |> strftime("%r")
{:ok, "12:30:59 PM"}

# Tuples in erlang datetime format will work like NaiveDateTime structs
iex> {{2014,9,6},{17,10,20}} |> strftime("%A %Y-%m-%e %H:%M:%S")
{:ok, "Saturday 2014-09- 6 17:10:20"}

The ticks in the table above tells you what input is needed for the conversion spec. The table below shows which kinds of input you can use depending on which boxes are ticked:

Like strftime without the exclamation point, but returns the result without tagging it with :ok. Raises in case of errors.

Examples

# Passing NaiveDateTime struct
iex> {{2014,9,6},{17,10,20}} |> Calendar.NaiveDateTime.from_erl! |> strftime!("%A %Y-%m-%e %H:%M:%S")
"Saturday 2014-09- 6 17:10:20"
# Passing naive date time tuple
iex> {{2014,9,6},{17,10,20}} |> strftime!("%A %Y-%m-%e %H:%M:%S")
"Saturday 2014-09- 6 17:10:20"
# Passing Date struct
iex> {2014,9,6} |> Calendar.Date.from_erl! |> strftime!("%A %Y-%m-%e")
"Saturday 2014-09- 6"
# Passing Time struct
iex> {17,10,20} |> Calendar.Time.from_erl! |> strftime!("%H:%M:%S")
"17:10:20"