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fix: accept ISO 8601 'T' separator for naive datetimes #8

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Merged
jqnatividad merged 3 commits into from
May 18, 2026
Merged

fix: accept ISO 8601 'T' separator for naive datetimes #8

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537466a
fix(ymd_hms): accept ISO 8601 'T' separator for naive datetimes
jqnatividad May 18, 2026
b8414fe
perf(ymd_hms): tighten T/space separator regex to character class
jqnatividad May 18, 2026
5a6b51f
test(parse_unambiguous_dmy): assert Local date, not UTC date
jqnatividad May 18, 2026
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5 changes: 4 additions & 1 deletion README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -22,14 +22,17 @@ It also adds support for parsing dates in DMY format, with the `parse_with_prefe
"2017-11-25T22:34:50Z",
// rfc2822
"Wed, 02 Jun 2021 06:31:39 GMT",
// yyyy-mm-dd hh:mm:ss
// yyyy-mm-dd hh:mm:ss (separator: space or ISO 8601 'T')
"2014-04-26 05:24:37 PM",
"2021-04-30 21:14",
"2021-04-30 21:14:10",
"2021-04-30 21:14:10.052282",
"2014-04-26 17:24:37.123",
"2014-04-26 17:24:37.3186369",
"2012-08-03 18:31:59.257000000",
"2020-01-15T08:00",
"2020-01-15T08:00:00",
"2020-01-15T08:00:00.123456",
// yyyy-mm-dd hh:mm:ss z
"2017-11-25 13:31:15 PST",
"2017-11-25 13:31 PST",
Expand Down
60 changes: 53 additions & 7 deletions src/datetime.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -181,30 +181,55 @@ where
.map(Ok)
}

// yyyy-mm-dd hh:mm:ss
// yyyy-mm-dd hh:mm:ss (separator is space OR ISO 8601 'T')
// - 2014-04-26 05:24:37 PM
// - 2021-04-30 21:14
// - 2021-04-30 21:14:10
// - 2021-04-30 21:14:10.052282
// - 2014-04-26 17:24:37.123
// - 2014-04-26 17:24:37.3186369
// - 2012-08-03 18:31:59.257000000
// - 2020-01-15T08:00
// - 2020-01-15T08:00:00
// - 2020-01-15T08:00:00.123456
#[inline]
fn ymd_hms(&self, input: &str) -> Option<Result<DateTime<Utc>>> {
let re: &Regex = regex! {
r"^\d{4}-\d{2}-\d{2}\s+\d{2}:\d{2}(:\d{2})?(\.\d{1,9})?\s*(am|pm|AM|PM)?$"
r"^\d{4}-\d{2}-\d{2}[T\s]+\d{2}:\d{2}(:\d{2})?(\.\d{1,9})?\s*(am|pm|AM|PM)?$"

};
if !re.is_match(input) {
return None;
}

// Byte 10 is the date/time separator. The regex guarantees the input
// has at least 16 bytes and that byte 10 is either 'T' or ASCII
// whitespace, so picking the format-string family on this single byte
// avoids doubling the trial-parse chain for the common space case.
let (fmt_hms, fmt_hm, fmt_hms_f, fmt_ims_p, fmt_im_p) = if input.as_bytes()[10] == b'T' {
(
"%Y-%m-%dT%H:%M:%S",
"%Y-%m-%dT%H:%M",
"%Y-%m-%dT%H:%M:%S%.f",
"%Y-%m-%dT%I:%M:%S %P",
"%Y-%m-%dT%I:%M %P",
)
} else {
(
"%Y-%m-%d %H:%M:%S",
"%Y-%m-%d %H:%M",
"%Y-%m-%d %H:%M:%S%.f",
"%Y-%m-%d %I:%M:%S %P",
"%Y-%m-%d %I:%M %P",
)
};

self.tz
.datetime_from_str(input, "%Y-%m-%d %H:%M:%S")
.or_else(|_| self.tz.datetime_from_str(input, "%Y-%m-%d %H:%M"))
.or_else(|_| self.tz.datetime_from_str(input, "%Y-%m-%d %H:%M:%S%.f"))
.or_else(|_| self.tz.datetime_from_str(input, "%Y-%m-%d %I:%M:%S %P"))
.or_else(|_| self.tz.datetime_from_str(input, "%Y-%m-%d %I:%M %P"))
.datetime_from_str(input, fmt_hms)
.or_else(|_| self.tz.datetime_from_str(input, fmt_hm))
.or_else(|_| self.tz.datetime_from_str(input, fmt_hms_f))
.or_else(|_| self.tz.datetime_from_str(input, fmt_ims_p))
.or_else(|_| self.tz.datetime_from_str(input, fmt_im_p))
.ok()
.map(|parsed| parsed.with_timezone(&Utc))
.map(Ok)
Expand Down Expand Up @@ -811,6 +836,22 @@ mod tests {
"2012-08-03 18:31:59.257000000",
Utc.ymd(2012, 8, 3).and_hms_nano(18, 31, 59, 257000000),
),
// ISO 8601 with 'T' separator and no timezone (naive wall-clock).
// Must agree with the space-separated form on the same wall-clock instant.
("2020-01-15T08:00", Utc.ymd(2020, 1, 15).and_hms(8, 0, 0)),
("2020-01-15T08:00:00", Utc.ymd(2020, 1, 15).and_hms(8, 0, 0)),
(
"2020-01-15T08:00:00.123",
Utc.ymd(2020, 1, 15).and_hms_milli(8, 0, 0, 123),
),
(
"2020-01-15T08:00:00.123456",
Utc.ymd(2020, 1, 15).and_hms_micro(8, 0, 0, 123456),
),
(
"2020-01-15T08:00:00.123456789",
Utc.ymd(2020, 1, 15).and_hms_nano(8, 0, 0, 123456789),
),
];

for &(input, want) in test_cases.iter() {
Expand All @@ -822,6 +863,11 @@ mod tests {
)
}
assert!(parse.ymd_hms("not-date-time").is_none());

// T and space separators must produce the same instant.
let t_form = parse.ymd_hms("2020-01-15T08:00:00").unwrap().unwrap();
let space_form = parse.ymd_hms("2020-01-15 08:00:00").unwrap().unwrap();
assert_eq!(t_form, space_form, "T-separator vs space disagree");
}

#[test]
Expand Down
57 changes: 55 additions & 2 deletions src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -756,9 +756,16 @@ mod tests {

#[test]
fn parse_unambiguous_dmy() {
// `parse()` uses Local timezone and pads date-only inputs with the
// current time of day, so the resulting UTC date can roll by ±1 day
// depending on host TZ and the moment the test runs. Assert on the
// Local date — that's what `parse()` actually models for this input.
assert_eq!(
super::parse("31/3/22").unwrap().date(),
Utc.ymd(2022, 3, 31)
super::parse("31/3/22")
.unwrap()
.with_timezone(&Local)
.date(),
Local.ymd(2022, 3, 31)
);
assert_eq!(
super::parse_with_preference("3/31/22", true)
Expand All @@ -773,4 +780,50 @@ mod tests {
Utc.ymd(2021, 7, 31)
);
}

// Regression: ISO 8601 with 'T' separator and no timezone (e.g. Python's
// datetime.isoformat() without astimezone) must parse via the naive
// wall-clock path, matching the equivalent space-separated form.
#[test]
fn parse_iso_t_no_tz() {
// Bare T, no fractional, no tz.
let got = super::parse_with_preference("2020-01-15T08:00:00", false).unwrap();
assert_eq!(got, Utc.ymd(2020, 1, 15).and_hms(8, 0, 0));

// T, no seconds, no tz.
let got = super::parse_with_preference("2020-01-15T08:00", false).unwrap();
assert_eq!(got, Utc.ymd(2020, 1, 15).and_hms(8, 0, 0));

// T with millisecond + microsecond + nanosecond precision.
for (input, want) in [
(
"2020-01-15T08:00:00.123",
Utc.ymd(2020, 1, 15).and_hms_milli(8, 0, 0, 123),
),
(
"2020-01-15T08:00:00.123456",
Utc.ymd(2020, 1, 15).and_hms_micro(8, 0, 0, 123456),
),
(
"2020-01-15T08:00:00.123456789",
Utc.ymd(2020, 1, 15).and_hms_nano(8, 0, 0, 123456789),
),
] {
assert_eq!(
super::parse_with_preference(input, false).unwrap(),
want,
"parse_iso_t_no_tz/{input}"
);
}

// T-form and space-form must produce the same instant.
assert_eq!(
super::parse_with_preference("2020-01-15T08:00:00", false).unwrap(),
super::parse_with_preference("2020-01-15 08:00:00", false).unwrap(),
);

// Existing tz-bearing T-forms must continue to parse (no regression).
assert!(super::parse_with_preference("2020-01-15T08:00:00Z", false).is_ok());
assert!(super::parse_with_preference("2020-01-15T08:00:00+00:00", false).is_ok());
}
}
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