Is empty

<Collection> ->isEmpty

Returns a value of true if <Collection> contains no elements (that is, has no children). ->isEmpty does not check for an empty or null value of an attribute, but instead checks for existence of elements within the collection. As such, a unique alias must be used to represent the <Collection> being tested.

The Operators row of the table in Summary Table of Vocabulary Usage Restriction applies. No special exceptions.

This sample Rulesheet uses ->isEmpty to determine if collection1 has any elements. Note the use of unique alias collection1 to represent the collection of Entity2 associated with Entity1.

A sample Ruletest provides two example collection1. The following illustration shows Input and Output panels