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INFORMATION FOR DEVELOPERS

Once the Date API is installed, all functions in the API are available to be

used anywhere by any module.

The API uses the PHP 5.2 date functions to create and manipulate dates.

Example, the following will create a date for the local value in one

timezone, adjust it to a different timezone, then return the offset in seconds

in the new timezone for the input date; The offset will be adjusted for both

the timezone difference and daylight savings time, if necessary:

$date = date_create('2007-03-11 02:00:00', timezone_open('America/Chicago'));

$chicago_time = date_format($date, 'Y-m-d H:i');

print 'At '. $chicago_time .' in Chicago, the timezone offset in seconds

  was '. date_offset_get($date);

date_timezone_set($date, timezone_open('Europe/Berlin');

$berlin_time = date_format($date, 'Y-m-d H:i');

print 'It was '. $berlin_time .' in Berlin when it

  was '. $chicago_time .' in Chicago.';

print 'At that time in Berlin, the timezone offset in seconds was

  '. date_offset_get($date);

A helper class is available, new DateObject($string, $timezone, $format), where

$string is a unixtimestamp, an ISO date, or a string like YYYY-MM-DD HH:MM:SS,

$timezone is the name of the timezone this date is in, and $format is the format

of date it is (DATE_FORMAT_UNIX, DATE_FORMAT_ISO, or DATE_FORMAT_DATETIME). It

creates and return a date object set to the right date and timezone.

Simpletest tests for these functions are included in the package.

Available functions include the following (more documentation is provided in

the files):

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Preconfigured arrays

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Both translated and untranslated values are available. The

date_week_days_ordered() function will shift an array of week day names so it

starts with the site's first day of the week, otherwise the weekday names start

with Sunday as the first value, which is the expected order for many php and sql

functions.

date_month_names();

date_month_names_abbr();

date_month_names_untranslated();

date_week_days();

date_week_days_abbr();

date_week_days_untranslated();

date_week_days_ordered();

date_years();

date_hours();

date_minutes();

date_seconds();

date_timezone_names();

date_ampm();

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Miscellaneous date manipulation functions

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Pre-defined constants and functions that will handle pre-1970 and post-2038

dates in both PHP 4 and PHP 5, in any OS. Dates can be converted from one

type to another and date parts can be extracted from any date type.

DATE_DATETIME

DATE_ISO

DATE_UNIX

DATE_ARRAY

DATE_OBJECT

DATE_ICAL

date_convert()

date_is_valid();

date_part_is_valid();

date_part_extract();

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Date calculation and navigation

============================================================================

date_difference() will find the time difference between any two days, measured

in seconds, minutes, hours, days, months, weeks, or years.

date_days_in_month();

date_days_in_year();

date_weeks_in_year();

date_last_day_of_month();

date_day_of_week();

date_day_of_week_name();

date_difference();

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Date regex and format helpers

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Pre-defined constants, an array of date format strings and their

equivalent regex strings.

DATE_REGEX_LOOSE is a very loose regex that will pull date parts out

of an ISO date with or without separators, using either 'T' or a space

to separate date and time, and with or without time.

date_format_date() is similar to format_date(), except it takes a

date object instead of a timestamp as the first parameter.

DATE_FORMAT_ISO

DATE_FORMAT_DATETIME

DATE_FORMAT_UNIX

DATE_FORMAT_ICAL

DATE_REGEX_ISO

DATE_REGEX_DATETIME

DATE_REGEX_LOOSE

date_format_date();

date_short_formats();

date_medium_formats();

date_long_formats();

date_format_patterns();

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Standardized ical parser and creator

============================================================================

The iCal parser is found in date_api_ical.inc, which is not included by default.

Include that file if you want to use these functions:

Complete rewrite of ical imports to parse vevents, vlocations, valarms,

and all kinds of timezone options and repeat rules for ical imports.

The function now sticks to parsing the ical into an array that can be used

in various ways. It no longer trys to convert timezones while parsing,

instead a date_ical_date_format() function is provided that can be used to

convert from the ical timezone to whatever timezone is desired in the

results. Repeat rules are parsed into an array which other modules can

manipulate however they like to create additional events from the results.

date_ical_export();

date_ical_import();

date_ical_date_format();

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Helpers for portable date SQL

============================================================================

The SQL functions are found in date_api_sql.inc, which is not included by

default. Include that file if you want to use these functions:

date_sql();

date_server_zone_adj();

date_sql_concat();

date_sql_pad();

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Date forms and validators

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Reusable, configurable, self-validating FAPI date elements are found in

date_api_elements.inc, which is not included by default. Include it

if you want to use these elements. To use them, create a form element

and set the '#type' to one of the following:

date_select

 The date_select element will create a collection of form elements, with a

 separate select or textfield for each date part. The whole collection will

 get reformatted back into a date value of the requested type during validation.

date_text

 The date_text element will create a textfield that can contain a whole

 date or any part of a date as text. The user input value will be re-formatted

 back into a date value of the requested type during validation.

date_timezone

 The date_timezone element will create a drop-down selector to pick a

 timezone name.

The custom date elements require a few other pieces of information to work

correctly, like #date_format and #date_type. See the internal documentation

for more information.

============================================================================

Date Popup Module

============================================================================

A new module is included in the package that will enable a popup jQuery

calendar date picker and timepicker in date and time fields.

It is implemented as a custom form element, so set '#type' to 'date_popup'

to use this element. See the internal documentation for more information.

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Date Repeat API

============================================================================

An API for repeating dates is available if installed. It can be used by

other modules to create a form element that will allow users to select

repeat rules and store those selections in an iCal RRULE string, and a

calculation function that will parse the RRULE and return an array of dates

that match those rules. The API is implemented in the Date module as a

new date widget if the Date Repeat API is installed.

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RDF Integration

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To make RDF easier to use, the base date themes (date_display_single and

date_display_range) have been expanded so they pass attributes and

RDF mappings for the field, if any, to the theme. If RDF is installed

and no other mappings are provided, the theme adds RDF information

to mark both the Start and End dates as 'xsd:dateTime' datatypes with the

property of 'dc:date'. This occurs in the theme preprocess layer, in

particular via the functions template_preprocess_date_display_single() and

template_preprocess_date_display_range().

To mark these as events instead, you could install the schemaorg

module, which will load the schema.org vocabulary. The mark the content type

that contains events as an 'Event', using the UI exposed by that

module and set the event start date field with the 'dateStart'

property and tag other fields in the content type with the appropriate

property types. The Date module theme will wrap the start and end

date output with appropriate markup.

If the result is not quite what you need, you should be able to implement your

own theme preprocess functions, e.g. MYTHEME_preprocess_date_display_single()

or MYTHEME_preprocess_date_display_range() and alter the attributes to use the

values you want.