XPath Keywords and System Variables

Last modified: August 20, 2024

Overview

In XPath, several keywords and system variables can be called as a comparison.

Keywords

Either of these keywords can be used to check whether an attribute has a value (any value) or if it has been left empty:

NULL
empty

Example

This query returns all the customers whose name is not known to the system:

    [Name = NULL]

    //Sales.Customer[Name = NULL]

These keywords can only be used in conjunction with attributes. The existence of associations cannot be confirmed in this manner. For more information on how to constrain on associations, see XPath Constraint Functions.

System Variables

System variables can be used to obtain system or date related values. The available tokens are described below.

Token	Description
`[%CurrentUser%]`	The GUID of the user currently logged in.
`[%CurrentObject%]`	The GUID of the active object (in the context).

User Roles

These will be created for each user role in your app. Here is an example:

Token	Description
`[%UserRole_Administrator%]`	The Administrator user role.

Here is an example for retrieving that user role:

The following tokens can be used to obtain a date and time value:

Token	Description
`[%CurrentDateTime%]`	The current date and time.
`[%BeginOfCurrentMinute%]`	The date and time at the beginning of the current minute.
`[%BeginOfCurrentMinuteUTC%]`	The date and time at the beginning of the current minute in UTC.
`[%EndOfCurrentMinute%]`	The date and time at the end of the current minute.
`[%EndOfCurrentMinuteUTC%]`	The date and time at the end of the current minute in UTC.
`[%BeginOfCurrentHour%]`	The date and time at the beginning of the current hour.
`[%BeginOfCurrentHourUTC%]`	The date and time at the beginning of the current hour in UTC.
`[%EndOfCurrentHour%]`	The date and time at the end of the current hour.
`[%EndOfCurrentHourUTC%]`	The date and time at the end of the current hour in UTC.
`[%BeginOfCurrentDay%]`	The date and time at the beginning of the current day.
`[%BeginOfCurrentDayUTC%]`	The date and time at the beginning of the current day in UTC.
`[%EndOfCurrentDay%]`	The date and time at the end of the current day.
`[%EndOfCurrentDayUTC%]`	The date and time at the end of the current day in UTC.
`[%BeginOfYesterday%]`	The date and time at the beginning of yesterday.
`[%BeginOfYesterdayUTC%]`	The date and time at the beginning of yesterday in UTC.
`[%EndOfYesterday%]`	The date and time at the end of yesterday.
`[%EndOfYesterdayUTC%]`	The date and time at the end of yesterday in UTC.
`[%BeginOfTomorrow%]`	The date and time at the beginning of tomorrow.
`[%BeginOfTomorrowUTC%]`	The date and time at the beginning of tomorrow in UTC.
`[%EndOfTomorrow%]`	The date and time at the end of tomorrow.
`[%EndOfTomorrowUTC%]`	The date and time at the end of tomorrow in UTC.
`[%BeginOfCurrentWeek%]`	The date and time at the beginning of the current week.
`[%BeginOfCurrentWeekUTC%]`	The date and time at the beginning of the current week in UTC.
`[%EndOfCurrentWeek%]`	The date and time at the end of the current week.
`[%EndOfCurrentWeekUTC%]`	The date and time at the end of the current week in UTC.
`[%BeginOfCurrentMonth%]`	The date and time at the beginning of the current month.
`[%BeginOfCurrentMonthUTC%]`	The date and time at the beginning of the current month in UTC.
`[%EndOfCurrentMonth%]`	The date and time at the end of the current month.
`[%EndOfCurrentMonthUTC%]`	The date and time at the end of the current month in UTC.
`[%BeginOfCurrentYear%]`	The date and time at the beginning of the current year.
`[%BeginOfCurrentYearUTC%]`	The date and time at the beginning of the current year in UTC.
`[%EndOfCurrentYear%]`	The date and time at the end of the current year.
`[%EndOfCurrentYearUTC%]`	The date and time at the end of the current year in UTC.

Do not use the UTC variants of these tokens (for example, [%BeginOfCurrentDayUTC%]) in client-side expressions if you want to assign the output to (or compare the output with) an attribute of type Date and time where Localize is disabled. In the client, the localization functionality is built into the attribute type itself, and using UTC functions causes the time zone conversion to be handled twice.

The following tokens can be used to add or subtract a period of time from a date and time token value:

Token	Description
`[%DayLength%]`	The length of one day (24 hour).
`[%HourLength%]`	The length of one hour.
`[%MinuteLength%]`	The length of one minute.
`[%SecondLength%]`	The length of one second.
`[%WeekLength%]`	The length of one week (seven days).
`[%MonthLength%]`	The length of one month.
`[%YearLength%]`	The length of one year.

These variables must be used as string values and placed between two quotes. Time-related tokens combined with period-related tokens must be placed within one string. See example 3.

Examples

This query returns only customers who have registered since the beginning of this week:

    [DateRegistered >= '[%BeginOfCurrentWeek%]']

    //Sales.Customer[DateRegistered >= '[%BeginOfCurrentWeek%]']

This query returns only customers who have registered this week:

    [DateRegistered >= '[%BeginOfCurrentWeek%]' and DateRegistered < '[%EndOfCurrentWeek%]']

    //Sales.Customer[DateRegistered >= '[%BeginOfCurrentWeek%]' and DateRegistered < '[%EndOfCurrentWeek%]']

This query returns only customers who have registered in the past three years:

    [DateRegistered > '[%BeginOfCurrentDay%] - 3 * [%YearLength%]']

    //Sales.Customer[DateRegistered > '[%BeginOfCurrentDay%] - 3 * [%YearLength%]']

This query returns users with the role “Administrator”:

    [System.UserRoles = '[%UserRole_Administrator%]']

    //System.User[System.UserRoles = '[%UserRole_Administrator%]']

Because system variables are written as a string (between quotes), it is not possible to use parentheses to group expressions.