Oihana Php Standards

helpers

Functions

isIso8601Date() : bool: Validates whether a string is a valid ISO 8601 calendar date.
isIso8601DateTime() : bool: Validates whether a string is a valid ISO 8601 date-time.
isIso8601Duration() : bool: Validates whether a string is a valid ISO 8601 duration format.
isIso8601Interval() : bool: Validates whether a string is a valid ISO 8601 time interval.
isIso8601Recurrence() : bool: Validates whether a string is a valid ISO 8601 recurring interval.
isIso8601Time() : bool: Validates whether a string is a valid ISO 8601 time format.
toIso8601Date() : string: Converts a DateTimeInterface object to its ISO 8601 calendar date string.
toIso8601DateTime() : string: Converts a DateTimeInterface object to its ISO 8601 date-time string.
toIso8601Duration() : string: Converts a DateInterval object to its ISO 8601 duration string representation.
toIso8601Time() : string: Converts a DateTimeInterface object to its ISO 8601 time string representation.

isIso8601Date()

Validates whether a string is a valid ISO 8601 calendar date.


    
                    isIso8601Date(string $date[, bool $strict = false ]) : bool

Accepted formats:

Extended: YYYY-MM-DD (e.g. "2026-05-14")
Basic : YYYYMMDD (e.g. "20260514"), unless $strict is true

The function checks both the syntactic format and the calendar validity (i.e. February 30 is rejected, leap years are honored).

Parameters

$date : string: The date string to validate
$strict : bool = false: If true, only the extended format YYYY-MM-DD is accepted (default: false)

Tags

example

isIso8601Date('2026-05-14');         // true
isIso8601Date('20260514');           // true (basic)
isIso8601Date('20260514', true);     // false (strict rejects basic)
isIso8601Date('2026-02-30');         // false (invalid calendar date)
isIso8601Date('2024-02-29');         // true  (leap year)
isIso8601Date('2023-02-29');         // false (not a leap year)
isIso8601Date('2026-5-14');          // false (month not zero-padded)

link

ISO 8601 calendar dates

author

Marc Alcaraz (ekameleon)

since

1.0.2

Return values

bool —

True if the string is a valid ISO 8601 date, false otherwise

isIso8601DateTime()

Validates whether a string is a valid ISO 8601 date-time.


    
                    isIso8601DateTime(string $value[, bool $strict = false ]) : bool

Accepted shape:

Date : YYYY-MM-DD (extended)
Sep. : T (mandatory in strict mode, space allowed otherwise)
Time : HH:MM:SS, optionally with fractional seconds (.fff...)
Offset: optional Z, ±HH:MM or ±HHMM

The function checks both the syntactic format and the calendar validity (February 30 is rejected, leap years are honored).

Parameters

$value : string: The date-time string to validate
$strict : bool = false: If true, the T separator is mandatory (default: false)

Tags

example

isIso8601DateTime('2026-05-14T08:15:30Z');         // true
isIso8601DateTime('2026-05-14T08:15:30+02:00');    // true
isIso8601DateTime('2026-05-14T08:15:30.123Z');     // true (milliseconds)
isIso8601DateTime('2026-05-14 08:15:30');          // true (space separator)
isIso8601DateTime('2026-05-14 08:15:30', true);    // false (strict requires T)
isIso8601DateTime('2026-02-30T00:00:00Z');         // false (invalid calendar date)
isIso8601DateTime('2026-05-14T24:00:00');          // false (invalid hour)

link

ISO 8601 combined representations

author

Marc Alcaraz (ekameleon)

since

1.0.2

Return values

bool —

True if the string is a valid ISO 8601 date-time, false otherwise

isIso8601Duration()

Validates whether a string is a valid ISO 8601 duration format.


    
                    isIso8601Duration(string $duration[, bool $strict = false ]) : bool

This function checks if a given string conforms to the ISO 8601 duration specification. The ISO 8601 duration format follows the pattern: P[n]Y[n]M[n]W[n]DT[n]H[n]M[n]S

Valid formats include:

Date components: P[n]Y[n]M[n]W[n]D (years, months, weeks, days)
Time components: PT[n]H[n]M[n]S (hours, minutes, seconds)
Combined: P[n]Y[n]M[n]DT[n]H[n]M[n]S
Zero duration: P0D, PT0S, P0Y, etc.

Rules:

Must start with 'P' (period designator)
'T' separates date and time components (required if time components are present)
At least one component must be present
Components must be in correct order: Y, M, W/D, then T, then H, M, S
Negative durations are not part of ISO 8601 standard but PHP accepts them

Parameters

$duration : string: The duration string to validate
$strict : bool = false: If true, uses regex validation; if false, uses PHP's DateInterval parser (default: false)

Tags

example

validateIso8601Duration('P1Y2M3D'); // true
validateIso8601Duration('PT4H30M'); // true
validateIso8601Duration('P1W'); // true
validateIso8601Duration('P0D'); // true
validateIso8601Duration('INVALID'); // false
validateIso8601Duration('P'); // false (no components)
validateIso8601Duration('1Y2M'); // false (missing P)

// Strict mode validation (regex-based)
validateIso8601Duration('P1Y2M3D', true); // true
validateIso8601Duration('P1.5Y', true); // false (no decimals in strict mode)

// Form validation
if (!validateIso8601Duration($_POST['duration'])) {
    throw new Exception('Invalid duration format');
}

link

ISO 8601 Duration specification

PHP DateInterval constructor

author

Marc Alcaraz (ekameleon)

since

1.0.1

Return values

bool —

True if the string is a valid ISO 8601 duration, false otherwise

isIso8601Interval()

Validates whether a string is a valid ISO 8601 time interval.


    
                    isIso8601Interval(string $value) : bool

An interval is two ISO 8601 expressions joined by a / separator, in one of the following forms:

<start>/<end> — two strict date-times (e.g. 2026-05-14T00:00:00Z/2026-05-15T00:00:00Z)
<start>/<duration> — a start date-time and a duration (e.g. 2026-05-14T00:00:00Z/P1D)
<duration>/<end> — a duration and an end date-time (e.g. P1D/2026-05-15T00:00:00Z)

The single-<duration> short form (e.g. P1D alone) is intentionally rejected: use Iso8601Duration for that case. Open intervals (--/<end> and <start>/-- from ISO 8601:2019) are also rejected for now.

Date-time components are validated in strict mode (mandatory T separator).

Parameters

$value : string: The interval string to validate

Tags

example

isIso8601Interval('2026-05-14T00:00:00Z/2026-05-15T00:00:00Z'); // true
isIso8601Interval('2026-05-14T00:00:00Z/P1D');                  // true
isIso8601Interval('P1D/2026-05-15T00:00:00Z');                  // true
isIso8601Interval('P1D');                                        // false (use Iso8601Duration)
isIso8601Interval('P1D/P2D');                                    // false (two durations)
isIso8601Interval('--/2026-05-15T00:00:00Z');                    // false (open interval)

link

ISO 8601 Time intervals

author

Marc Alcaraz (ekameleon)

since

1.0.2

Return values

bool —

True if the string is a valid ISO 8601 interval, false otherwise

isIso8601Recurrence()

Validates whether a string is a valid ISO 8601 recurring interval.


    
                    isIso8601Recurrence(string $value) : bool

The format is R[n]/<interval> where:

R is the recurrence designator (required)
n is an optional non-negative integer count (absent means infinite)
<interval> is any valid ISO 8601 bounded interval — see isIso8601Interval()

Parameters

$value : string: The recurrence string to validate

Tags

example

isIso8601Recurrence('R/2026-05-14T00:00:00Z/P1D');     // true (infinite)
isIso8601Recurrence('R5/2026-05-14T00:00:00Z/P1D');    // true (5 occurrences)
isIso8601Recurrence('R0/2026-05-14T00:00:00Z/PT0S');   // true (zero, degenerate)
isIso8601Recurrence('R10/P1D/2026-05-15T00:00:00Z');   // true
isIso8601Recurrence('2026-05-14T00:00:00Z/P1D');       // false (missing R)
isIso8601Recurrence('R-1/P1D/2026-05-15T00:00:00Z');   // false (negative count)
isIso8601Recurrence('R/P1D');                          // false (interval must be bounded)

link

ISO 8601 Repeating intervals

author

Marc Alcaraz (ekameleon)

since

1.0.2

Return values

bool —

True if the string is a valid ISO 8601 recurrence, false otherwise

isIso8601Time()

Validates whether a string is a valid ISO 8601 time format.


    
                    isIso8601Time(string $time[, bool $strict = false ]) : bool

This function checks if a given string conforms to the ISO 8601 time specification. ISO 8601 time format includes:

Optional 'T' prefix
Hours (00-23)
Optional minutes (00-59)
Optional seconds (00-59, can be fractional)
Optional timezone offset (Z for UTC or ±HH:MM)

Examples of valid formats:

"T14:30:00Z" → 14:30:00 UTC
"T08:15:30+02:00" → 08:15:30 in UTC+2
"T23:59:59" → 23:59:59 local time (no offset)

Rules:

Hours must be 00-23
Minutes and seconds, if present, must be 00-59
Fractional seconds are allowed
Timezone, if present, must be 'Z' or ±HH:MM

Parameters

$time : string: The time string to validate
$strict : bool = false: If true, validates strictly with regex; if false, uses DateTimeImmutable parser (default: false)

Tags

example

isIso8601Time('T14:30:00Z');       // true
isIso8601Time('T08:15:30+02:00');  // true
isIso8601Time('T23:59:59');        // true
isIso8601Time('14:30:00');         // false (missing T)
isIso8601Time('INVALID');           // false

// Strict mode validation
isIso8601Time('T14:30:00.123Z', true); // true (fractional seconds allowed)
isIso8601Time('T14:60:00', true);      // false (invalid minutes)

link

ISO 8601 Time specification

PHP DateTimeImmutable documentation

author

Marc Alcaraz (ekameleon)

since

1.0.1

Return values

bool —

True if the string is a valid ISO 8601 time, false otherwise

toIso8601Date()

Converts a DateTimeInterface object to its ISO 8601 calendar date string.


    
                    toIso8601Date(DateTimeInterface $date[, bool $basic = false ]) : string

The output format is YYYY-MM-DD by default (ISO 8601 extended), or YYYYMMDD if $basic is true (ISO 8601 basic).

The time and timezone components of the input are ignored; only the calendar date (year, month, day) in the object's own timezone is used.

Parameters

$date : DateTimeInterface: The date to convert
$basic : bool = false: If true, returns the basic format YYYYMMDD (default: false)

Tags

example

use org\iso\helpers\toIso8601Date;
use DateTimeImmutable;

$dt = new DateTimeImmutable('2026-05-14 08:15:30');
echo toIso8601Date($dt);         // "2026-05-14"
echo toIso8601Date($dt, true);   // "20260514"

link

ISO 8601 calendar dates

author

Marc Alcaraz (ekameleon)

since

1.0.2

Return values

string —

The ISO 8601 date string, e.g. "2026-05-14" or "20260514"

toIso8601DateTime()

Converts a DateTimeInterface object to its ISO 8601 date-time string.


    
                    toIso8601DateTime(DateTimeInterface $dt[, string $precision = TimePrecision::SECONDS ][, bool $zulu = false ]) : string

Output shape:

YYYY-MM-DDTHH:MM:SS[.fff...]Z when offset is zero
YYYY-MM-DDTHH:MM:SS[.fff...]±HH:MM otherwise

The offset is normalized to ±HH:MM (or Z for UTC) regardless of the underlying timezone object, mirroring the behavior of toIso8601Time().

Parameters

$dt : DateTimeInterface: The date-time to convert
$precision : string = TimePrecision::SECONDS: One of the TimePrecision constants (default: TimePrecision::SECONDS)
$zulu : bool = false: If true, the value is first converted to UTC and rendered with the Z suffix (default: false)

Tags

throws

InvalidArgumentException

If $precision is not a recognized value

example

use org\iso\helpers\toIso8601DateTime;
use org\iso\TimePrecision;
use DateTimeImmutable;
use DateTimeZone;

$dt = new DateTimeImmutable('2026-05-14 08:15:30', new DateTimeZone('+02:00'));

echo toIso8601DateTime($dt);                                    // "2026-05-14T08:15:30+02:00"
echo toIso8601DateTime($dt, TimePrecision::MILLISECONDS);       // "2026-05-14T08:15:30.000+02:00"
echo toIso8601DateTime($dt, TimePrecision::SECONDS, true);      // "2026-05-14T06:15:30Z"

$utc = new DateTimeImmutable('2026-05-14 08:15:30', new DateTimeZone('UTC'));
echo toIso8601DateTime($utc);                         // "2026-05-14T08:15:30Z"

link

ISO 8601 combined representations

author

Marc Alcaraz (ekameleon)

since

1.0.2

Return values

string —

The ISO 8601 date-time string

toIso8601Duration()

Converts a DateInterval object to its ISO 8601 duration string representation.


    
                    toIso8601Duration(DateInterval $interval) : string

This function generates a normalized ISO 8601 duration string from a PHP DateInterval object. The ISO 8601 duration format follows the pattern: P[n]Y[n]M[n]DT[n]H[n]M[n]S where P is the duration designator, T separates date and time components.

Components:

Y: years
M: months (before T) or minutes (after T)
D: days
H: hours
M: minutes
S: seconds

Only non-zero components are included in the output string. If all components are zero, returns "P0D" (zero duration).

Parameters

$interval : DateInterval: The DateInterval object to convert

Tags

example

// Create a duration of 1 year, 2 months, and 3 days
$interval = new DateInterval('P1Y2M3D');
echo toIso8601Duration($interval); // Output: "P1Y2M3D"

// Create a duration of 4 hours and 30 minutes
$interval = new DateInterval('PT4H30M');
echo toIso8601Duration($interval); // Output: "PT4H30M"

// Create a complex duration
$interval = new DateInterval('P2Y3M15DT12H45M30S');
echo toIso8601Duration($interval); // Output: "P2Y3M15DT12H45M30S"

// Create an interval from date difference
$start = new DateTime('2024-01-01');
$end = new DateTime('2024-12-31');
$interval = $start->diff($end);
echo toIso8601Duration($interval); // Output: "P11M30D"

// Zero duration
$interval = new DateInterval('PT0S');
echo toIso8601Duration($interval); // Output: "P0D"

link

ISO 8601 Duration specification

PHP DateInterval documentation

author

Marc Alcaraz (ekameleon)

since

1.0.1

Return values

string —

The ISO 8601 duration string (e.g., "P1Y2M3DT4H5M6S", "PT30M", "P0D")

toIso8601Time()

Converts a DateTimeInterface object to its ISO 8601 time string representation.


    
                    toIso8601Time(DateTimeInterface $time) : string

This function generates a normalized ISO 8601 time string from any PHP DateTimeInterface object (DateTime or DateTimeImmutable). The output format is:

"THH:MM:SSZ" for UTC (zero offset)
"THH:MM:SS±HH:MM" for non-zero offsets

The 'T' prefix separates the time from a potential date component, and the timezone designator can be 'Z' for UTC or a ±HH:MM offset.

Parameters

$time : DateTimeInterface: The time to convert to ISO 8601 format

Tags

example

use org\iso\helpers\toIso8601Time;
use DateTimeImmutable;
use DateTimeZone;

$dt = new DateTimeImmutable('14:30:00', new DateTimeZone('UTC'));
echo toIso8601Time($dt); // "T14:30:00Z"

$dt2 = new DateTimeImmutable('08:15:30', new DateTimeZone('+02:00'));
echo toIso8601Time($dt2); // "T08:15:30+02:00"

link

ISO 8601 Time specification

PHP DateTimeInterface documentation

PHP DateTimeImmutable documentation

author

Marc Alcaraz (ekameleon)

since

1.0.1

Return values

string —

The ISO 8601 time string, e.g. "T14:30:00Z" or "T08:15:30+02:00"

helpers

Table of Contents

Functions

Functions

isIso8601Date()

Parameters

Tags

Return values

isIso8601DateTime()

Parameters

Tags

Return values

isIso8601Duration()

Parameters

Tags

Return values

isIso8601Interval()

Parameters

Tags

Return values

isIso8601Recurrence()

Parameters

Tags

Return values

isIso8601Time()

Parameters

Tags

Return values

toIso8601Date()

Parameters

Tags

Return values

toIso8601DateTime()

Parameters

Tags

Return values

toIso8601Duration()

Parameters

Tags

Return values

toIso8601Time()

Parameters

Tags

Return values