Specifies the aggregate function to be checked by the current rule.
A Devexpress.Data.Filtering.Aggregate enumeration value which specifies the aggregate function to be checked by the current rule.
When applied to collection properties, the RuleValueComparison can use aggregate functions. When a value is assigned to the TargetCollectionAggregate property, the validation rule checks the specified aggregate function.
RuleValueComparison is not checked if the collection property is empty. Use the RuleRequiredFieldAttribute instead.