there is one (object)

This construct tests whether the current dataset contains one and only one object of a given type.

Purpose

You use this construct to determine whether the current dataset or the specified collection contains one and only one occurrence of a particular object.

Syntax

there is one <object> [in <list>] [where <test>,*]

Description

Use the optional in clause to apply the test to a specific collection of objects. Use one or more optional where clauses to filter the objects to be counted with one or more conditions.

This construct can only be used in the if part of a rule.

Example

The following condition tests if there is one Gold customer in the set of objects provided to the rule engine for execution.

if
   there is one customer
      where the category of this customer is Gold
then...