Date QML Type

Provides date functions. More...

• List of all members, including inherited members

Methods

• string fromLocaleDateString(locale, dateString, format)
• string fromLocaleString(locale, dateTimeString, format)
• string fromLocaleTimeString(locale, timeString, format)
• string timeZoneUpdated()
• string toLocaleDateString(locale, format)
• string toLocaleString(locale, format)
• string toLocaleTimeString(locale, format)

Detailed Description

The QML Date object extends the JS Date object with locale aware functions.

Functions that accept a format argument take either Locale.LongFormat, Locale.ShortFormat, Locale.NarrowFormat enumeration values, or a string specifying the format.

The form of the supported format strings is as described in the documentation of QDate::toString(), QTime::toString() and QDateTime::toString().

If the date is invalid, an empty string is returned.

Format Enumeration Values

Use the enumeration values when you want a format that matches the locale preferences.

The format that the enumerations represent will depend on your locale, but also the method that the enumeration is used for.

For example, for the en_US locale, these format strings are used:

Further Notes

Using the locale-aware functions to perform date or time formatting can result in incorrectly formatted times, due to an inconsistency in specification between Qt and JS. ECMA-262 specifies that historical dates should be intrepreted by projecting the current rules for daylight-saving onto past years, while Qt uses historical data (where available) to determine whether daylight-saving was in effect for a given date. Therefore, constructing a Date value in JS and converting it to a string using the locale-aware functions can yield a result incorrect by one hour, if DST is currently in effect, while it was not for the time specified, or vice versa.

There are different date formats with different understandings of negative years. Common human language does not have a year 0. The year after 1BC is 1AD. This understanding is reflected when printing or parsing dates in one of the formats not standardized by ECMAScript. That is: toString(), toLocaleString(), toUTCString() and friends. ECMAScript does standardize one format: ISO 8601. This is what you get when you call toISOString(). This format does include a year 0, which is 1BC in other formats. Thus you get different years when printing negative dates with toISOString() and toString().

When setting the year using the Date constructor or set(UTC)FullYear(), the convention set by ISO 8601 is used and 0 is a valid year. This means negative years set with the constructor or set(UTC)FullYear() are zero-based and thus offset by one year from what is printed with toString() and friends. Parsing the output of any of the to*String() methods will yield the same date value you printed from. Date.parse() will recognize the different formats and their convention on the existence of year 0.

Note that all this is different from what you get in other JavaScript implementations which usually treat year 0 as valid in all string representations. As the date formats are "implementation-dependent" in the ECMAScript standard, this is still valid, though.

See also Locale.

Method Documentation

import QtQml 2.0

QtObject {
    property var locale: Qt.locale()
    property date currentDate: new Date()
    property string dateString

    Component.onCompleted: {
        dateString = currentDate.toLocaleDateString();
        print(Date.fromLocaleDateString(dateString));
    }
}

import QtQml 2.0

QtObject {
    property var locale: Qt.locale()
    property string dateTimeString: "Tue 2013-09-17 10:56:06"

    Component.onCompleted: {
        print(Date.fromLocaleString(locale, dateTimeString, "ddd yyyy-MM-dd hh:mm:ss"));
    }
}

import QtQml 2.2

QtObject {
    property var locale: Qt.locale()
    property date currentTime: new Date()
    property string timeString

    Component.onCompleted: {
        timeString = currentTime.toLocaleTimeString(locale, Locale.ShortFormat);
        print(Date.fromLocaleTimeString(locale, timeString, Locale.ShortFormat));
    }
}

property string selectedTimeZone

onSelectedTimeZoneChanged: {
    MyFunctions.setSystemTimeZone(selectedTimeZone)
    Date.timeZoneUpdated()
}

import QtQuick 2.0

Text {
    text: "The date is: " + new Date().toLocaleDateString(Qt.locale("de_DE"))
}

import QtQuick 2.0

Text {
    text: "The date is: " + new Date().toLocaleString(Qt.locale("de_DE"))
}

import QtQuick 2.0

Text {
    text: "The date is: " + new Date().toLocaleTimeString(Qt.locale("de_DE"))
}