6 Expression macros

Overview

Expression macros are useful for formula calculations. They are calculated by expanding all macros inside and evaluating the resulting expression.

Expression macros have a special syntax:

{?MACRO}

See example of using an expression macro in the event name.

Usage

In the following locations:

• graph names
• map element labels
• map shape labels
• map link labels

only a single function, from the following set: avg, last, max, min, is allowed as an expression macro, e.g.:

{?avg(/{HOST.HOST}/key,1h)}

Expressions such as {?last(/host/item1)/last(/host/item2)}, {?count(/host/item1,5m)} and {?last(/host/item1)*10} are incorrect in these locations.

However, in:

• trigger event names
• trigger-based notifications and commands
• problem update notifications and commands

complex expressions are allowed, e.g.:

{?trendavg(/host/item1,1M:now/M)/trendavg(/host/item1,1M:now/M-1y)*100}

See also:

• Supported macros for a list of supported locations of the expression macro
• Example of using an expression macro in the event name