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Respect floating DATE-TIME values during parsing #52

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4 changes: 2 additions & 2 deletions lib/ical.ex
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Original file line number Diff line number Diff line change
Expand Up @@ -12,7 +12,7 @@ defmodule ICal do
todos: [],
journals: [],
timezones: %{},
default_timezone: "Etc/UTC",
default_timezone: nil,
name: nil,
custom_properties: %{},
__other_components: []
Expand Down Expand Up @@ -40,7 +40,7 @@ defmodule ICal do
todos: [ICal.Todo.t()],
journals: [ICal.Journal.t()],
timezones: %{String.t() => ICal.Timezone.t()},
default_timezone: String.t(),
default_timezone: String.t() | nil,
name: String.t() | nil,
custom_properties: custom_properties
}
Expand Down
24 changes: 19 additions & 5 deletions lib/ical/deserialize.ex
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Expand Up @@ -415,7 +415,7 @@ defmodule ICal.Deserialize do

# convert a string to a proper timezone, this includes ones with a /
# but also ones like Central Standard Time, so we try our best to normalize those
# all else fails, assume UTC
# all else fails, use the calendar default timezone if one was declared
def to_timezone(timezone, default \\ "Etc/UTC")
def to_timezone(nil, default), do: default

Expand All @@ -427,6 +427,9 @@ defmodule ICal.Deserialize do
ICal.Deserialize.Timezone.windows_to_olson(timezone) != nil ->
ICal.Deserialize.Timezone.windows_to_olson(timezone)

is_nil(default) ->
nil

true ->
default
Comment on lines +430 to 434

@aseigo aseigo Jul 3, 2026

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If default is nil, then returning default will in the true branch will return nil. So I think this change can be removed?

end
Expand All @@ -440,7 +443,8 @@ defmodule ICal.Deserialize do

It returns `nil` for ill-formed dates or datetime strings.
"""
@spec to_date(String.t() | nil, map, ICal.t()) :: Date.t() | DateTime.t() | nil
@spec to_date(String.t() | nil, map, ICal.t()) ::
Date.t() | DateTime.t() | NaiveDateTime.t() | nil
def to_date(nil, _params, _calendar), do: nil
Comment on lines +446 to 448

@aseigo aseigo Jul 3, 2026

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This is a breaking change to the API. which will break code that does not currently expect / handle NaiveDateTimes.

This would mean either bumping the major version of the library (which can be done), or finding a way to avoid introducing a new incompatible data type. It probably requires the new type, so this will also need a bump to 3.0 in the mix.exs.


def to_date(date_string, %{"VALUE" => "DATE"}, _calendar) do
Expand All @@ -457,11 +461,21 @@ defmodule ICal.Deserialize do
end

def to_date(date_string, %{"TZID" => timezone}, %ICal{default_timezone: default_timezone}) do
# Microsoft Outlook calendar .ICS files report times in Greenwich Standard Time (UTC +0)
# so just convert this to UTC
timezone = to_timezone(timezone, default_timezone)

to_date_in_timezone(date_string, timezone)
if timezone == nil do
to_local_date(date_string)
else
to_date_in_timezone(date_string, timezone)
end
end

def to_date(<<_::binary-size(15), "Z">> = date_string, _params, _calendar) do
to_date_in_timezone(date_string, "Etc/UTC")
end

def to_date(date_string, _params, %ICal{default_timezone: nil}) do
to_local_date(date_string)
Comment on lines +466 to +478

@aseigo aseigo Jul 3, 2026

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It would probably be easier to add this to to_date_int_timezone as it already parses the trailing Z for UTC. so that could be checked there to set the timezone to Etc/UTC if the timezone passed in as the second parameter is nil. Perhaps something like:

  def to_date_in_timezone(date_string, timezone) do
    # datetime in the form "{YYYY}{0M}{0D}T{h24}{m}{s}[Z]"
    with <<y::binary-size(4), m::binary-size(2), d::binary-size(2), ?T, t_h::binary-size(2),
           t_m::binary-size(2), t_s::binary-size(2), rest::binary>>
         when rest == "" or rest == "Z" <- date_string,
         {year, ""} <- Integer.parse(y),
         {month, ""} <- Integer.parse(m),
         {day, ""} <- Integer.parse(d),
         {hour, ""} <- Integer.parse(t_h),
         {minute, ""} <- Integer.parse(t_m),
         {second, ""} <- Integer.parse(t_s) do
      to_date_in_timezone(year, month, day, hour, minute, second, rest, timezone)
    else
      _ -> nil
    end
  end

  defp to_date_in_timezone(year, month, day, hour, minute, second, "Z", _timezone) do
    to_date_in_timezone(year, month, day, hour, minute, second, "Z", "Etc/UTC")
  end

  defp to_date_in_timezone(year, month, day, hour, minute, second, _suffix, nil) do
    case NaiveDateTime.new(year, month, day, hour, minute, second) do
      {:ok, datetime} -> datetime
      _ -> nil
    end
  end

  defp to_date_in_timezone(year, month, day, hour, minute, second, _suffix, timezone) do
    with {:ok, date} <- Date.new(year, month, day),
         {:ok, time} <- Time.new(hour, minute, second) do
      ICal.as_valid_datetime(date, time, timezone)
    else
      _ -> nil
    end
  end

  @doc "Parses a local date string as a NaiveDatetime, returning `nil` on failure"
  @spec to_local_date(String.t()) :: NaiveDateTime.t() | nil
  def to_local_date(date_string) do
    # Ensure there is no trailing 'Z' by only passing in the first 15 characters.
    to_date_in_timezone(String.slice(date_string, 0, 15), nil)
  end

end

def to_date(date_string, _params, %ICal{default_timezone: default_timezone}) do
Expand Down
16 changes: 8 additions & 8 deletions lib/ical/event.ex
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Expand Up @@ -39,14 +39,14 @@ defmodule ICal.Event do

@type t :: %__MODULE__{
uid: String.t() | nil,
dtstamp: DateTime.t() | nil,
created: DateTime.t() | nil,
dtstart: Date.t() | DateTime.t() | nil,
dtend: Date.t() | DateTime.t() | nil,
modified: Date.t() | nil,
recurrence_id: Date.t() | nil,
exdates: [Date.t() | DateTime.t()],
rdates: [Date.t() | DateTime.t() | ICal.period()],
dtstamp: DateTime.t() | NaiveDateTime.t() | nil,
created: DateTime.t() | NaiveDateTime.t() | nil,
dtstart: Date.t() | DateTime.t() | NaiveDateTime.t() | nil,
dtend: Date.t() | DateTime.t() | NaiveDateTime.t() | nil,
modified: Date.t() | DateTime.t() | NaiveDateTime.t() | nil,
recurrence_id: Date.t() | DateTime.t() | NaiveDateTime.t() | nil,
exdates: [Date.t() | DateTime.t() | NaiveDateTime.t()],
rdates: [Date.t() | DateTime.t() | NaiveDateTime.t() | ICal.period()],
Comment on lines +42 to +49

@aseigo aseigo Jul 3, 2026

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Seeing all these types added, it would probably make sense to introduce custom types in ical.ex such as:

@type rfc5455_datetime :: DateTime.t() | NativeDateTime.t()
@type maybe_rfc5455_datetime :: nil | rfc5455_datetime
@type rfc5455_date :: Date.t() | rfc5455_datetime
@type maybe_rfc5455_date :: nil | rfc5455_date

This would make things more succinct and less prone to accidental omissions, as we could then right this as:

          dtstamp: ICal.maybe_rfc5455_datetime(),
          created:  ICal.maybe_rfc5455_datetime(),
          dtstart:  ICal.maybe_rfc5455_date(),
          exdates: [ICal.rfc5455_date],

wdyt?

rrule: ICal.Recurrence.t() | nil,
class: String.t() | nil,
description: String.t() | nil,
Expand Down
18 changes: 9 additions & 9 deletions lib/ical/journal.ex
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Expand Up @@ -40,24 +40,24 @@ defmodule ICal.Journal do

@type t :: %__MODULE__{
uid: String.t(),
dtstamp: DateTime.t(),
created: nil | DateTime.t(),
completed: nil | DateTime.t(),
modified: nil | DateTime.t(),
recurrance_id: nil | DateTime.t() | Date.t(),
exdates: [Date.t() | DateTime.t()],
rdates: [Date.t() | DateTime.t() | ICal.period()],
dtstamp: DateTime.t() | NaiveDateTime.t(),
created: nil | DateTime.t() | NaiveDateTime.t(),
completed: nil | DateTime.t() | NaiveDateTime.t(),
modified: nil | DateTime.t() | NaiveDateTime.t(),
recurrance_id: nil | DateTime.t() | NaiveDateTime.t() | Date.t(),
exdates: [Date.t() | DateTime.t() | NaiveDateTime.t()],
rdates: [Date.t() | DateTime.t() | NaiveDateTime.t() | ICal.period()],
class: nil | String.t(),
description: [String.t()],
dtstart: nil | DateTime.t() | Date.t(),
dtstart: nil | DateTime.t() | NaiveDateTime.t() | Date.t(),
organizer: nil | String.t(),
priority: non_neg_integer,
sequence: non_neg_integer,
status: :need_action | :completed | :in_process | :cancelled | nil,
summary: nil | String.t(),
url: nil | String.t(),
rrule: nil | ICal.Recurrence.t(),
due: nil | DateTime.t() | Date.t(),
due: nil | DateTime.t() | NaiveDateTime.t() | Date.t(),
duration: nil | ICal.Duration.t(),
alarms: [ICal.Alarm.t()],
attachments: [ICal.Attachment.t()],
Expand Down
18 changes: 9 additions & 9 deletions lib/ical/todo.ex
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Expand Up @@ -44,16 +44,16 @@ defmodule ICal.Todo do

@type t :: %__MODULE__{
uid: String.t(),
dtstamp: DateTime.t(),
created: nil | DateTime.t(),
completed: nil | DateTime.t(),
modified: nil | DateTime.t(),
recurrance_id: nil | DateTime.t() | Date.t(),
exdates: [Date.t() | DateTime.t()],
rdates: [Date.t() | DateTime.t() | ICal.period()],
dtstamp: DateTime.t() | NaiveDateTime.t(),
created: nil | DateTime.t() | NaiveDateTime.t(),
completed: nil | DateTime.t() | NaiveDateTime.t(),
modified: nil | DateTime.t() | NaiveDateTime.t(),
recurrance_id: nil | DateTime.t() | NaiveDateTime.t() | Date.t(),
exdates: [Date.t() | DateTime.t() | NaiveDateTime.t()],
rdates: [Date.t() | DateTime.t() | NaiveDateTime.t() | ICal.period()],
class: nil | String.t(),
description: nil | String.t(),
dtstart: nil | DateTime.t() | Date.t(),
dtstart: nil | DateTime.t() | NaiveDateTime.t() | Date.t(),
geo: nil | ICal.geo(),
location: nil | String.t(),
organizer: nil | String.t(),
Expand All @@ -64,7 +64,7 @@ defmodule ICal.Todo do
summary: nil | String.t(),
url: nil | String.t(),
rrule: nil | ICal.Recurrence.t(),
due: nil | DateTime.t() | Date.t(),
due: nil | DateTime.t() | NaiveDateTime.t() | Date.t(),
duration: nil | ICal.Duration.t(),
alarms: [ICal.Alarm.t()],
attachments: [ICal.Attachment.t()],
Expand Down
71 changes: 69 additions & 2 deletions test/ical/deserialize_test.exs
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Expand Up @@ -201,6 +201,50 @@ defmodule ICal.DeserializeTest do
assert ~D[1998-01-19] == ICal.Deserialize.to_date("19980119", %{"VALUE" => "DATE"}, %ICal{})
end

test "to_date/3 parses a floating DATE-TIME as a naive datetime" do
assert ~N[1998-01-19 02:00:00] ==
ICal.Deserialize.to_date("19980119T020000", %{}, %ICal{})
end

test "to_date/3 parses a floating DATE-TIME in the calendar default timezone when set" do
result =
ICal.Deserialize.to_date(
"19980119T020000",
%{},
%ICal{default_timezone: "America/Chicago"}
)

assert %DateTime{
year: 1998,
month: 1,
day: 19,
hour: 2,
minute: 0,
second: 0,
time_zone: "America/Chicago"
} = result
end

test "to_date/3 parses a UTC DATE-TIME as a UTC datetime" do
assert ~U[1998-01-19 02:00:00Z] ==
ICal.Deserialize.to_date("19980119T020000Z", %{}, %ICal{})
end

test "to_date/3 parses a DATE-TIME with TZID in that timezone" do
result =
ICal.Deserialize.to_date("19980119T020000", %{"TZID" => "America/Chicago"}, %ICal{})

assert %DateTime{
year: 1998,
month: 1,
day: 19,
hour: 2,
minute: 0,
second: 0,
time_zone: "America/Chicago"
} = result
end

test "to_date/3 returns nil for an unparseable VALUE=DATE string" do
assert nil == ICal.Deserialize.to_date("garbage", %{"VALUE" => "DATE"}, %ICal{})
end
Expand Down Expand Up @@ -298,8 +342,31 @@ defmodule ICal.DeserializeTest do
# olson
assert event.dtend.time_zone == "America/Chicago"

# unrecognized tz
assert event.dtstamp.time_zone == "Etc/UTC"
# unrecognized tz without a calendar default timezone
assert event.dtstamp == ~N[2222-12-24 08:30:00]
end

test "unrecognized TZID falls back to the calendar default timezone when set" do
ics = """
BEGIN:VCALENDAR
X-WR-TIMEZONE:Europe/Zurich
BEGIN:VEVENT
DTSTAMP;TZID=Garbage:22221224T083000
END:VEVENT
END:VCALENDAR
"""
Comment on lines +350 to +357

@aseigo aseigo Jul 3, 2026

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This should be put into a file in test/data/ and loaded with Helper.test_data/1


%ICal{events: [event]} = ICal.from_ics(ics)

assert %DateTime{
year: 2222,
month: 12,
day: 24,
hour: 8,
minute: 30,
second: 0,
time_zone: "Europe/Zurich"
} = event.dtstamp
end

test "with CR+LF line endings" do
Expand Down
31 changes: 27 additions & 4 deletions test/ical_test.exs
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Expand Up @@ -63,7 +63,7 @@ defmodule ICalTest do
assert calendar.version == "2.0"
assert calendar.product_id == "-//Elixir ICal//EN"
assert calendar.method == "REQUEST"
assert calendar.default_timezone == "Etc/UTC"
assert calendar.default_timezone == nil
assert calendar.custom_properties == %{}
end

Expand All @@ -77,14 +77,37 @@ defmodule ICalTest do
assert Fixtures.calendar(:custom_properties) == calendar
end

test "ICal with custom tz alter dates" do
test "ICal with custom tz does not alter UTC dates" do
dtstamp = ~U[2015-12-24 08:00:00Z]

%ICal{events: [%ICal.Event{dtstamp: parsed_date}]} =
Helper.test_data("custom_calendar_tz") |> ICal.from_ics()

assert dtstamp != parsed_date
assert parsed_date.time_zone == "Europe/Zurich"
assert dtstamp == parsed_date
end

test "ICal with custom tz applies default timezone to floating dates" do
ics = """
BEGIN:VCALENDAR
X-WR-TIMEZONE:Europe/Zurich
BEGIN:VEVENT
UID:1
DTSTART:20151224T080000
END:VEVENT
END:VCALENDAR
"""
Comment on lines +90 to +98

@aseigo aseigo Jul 3, 2026

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This should be put into a file in test/data/ and loaded with Helper.test_data/1


%ICal{events: [%ICal.Event{dtstart: parsed_date}]} = ICal.from_ics(ics)

assert %DateTime{
year: 2015,
month: 12,
day: 24,
hour: 8,
minute: 0,
second: 0,
time_zone: "Europe/Zurich"
} = parsed_date
end

test "ICal.to_ics/1 of a calendar with an event, as in README" do
Expand Down
2 changes: 1 addition & 1 deletion test/support/fixtures.ex
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Expand Up @@ -499,7 +499,7 @@ defmodule ICal.Test.Fixtures do
}
}
],
default_timezone: "Etc/UTC"
default_timezone: nil
}
end

Expand Down