RuleObjectExistsAttribute(String, DefaultContexts, String) Constructor
Initializes a new instance of the RuleObjectExistsAttribute class.
A string value representing the current rule identifier. You can pass an empty value as the id parameter. An appropriate identifier will begenerated automatically, and set for the ID property of the Validation | Rules | Rule node in the Application Model.
A DefaultContexts enumeration value that specifies a context for checking the current rule. This value is set for the RuleBaseAttribute.TargetContextIDs property.
A string value representing the criteria that must be satisfied by the target type objects.
If you are going to set a custom message template instead of a default one, use a constructor with the messageTemplate parameter.
The common rules of writing a criteria are described in the Ways to Build Criteria topic. In addition, you can use the following construction:
PropertyName = '@PropertyName' (the operator is optional). @PropertyName represents a parameter that is set to the value of the PropertyName property of the currently validated object, when the rule is checked.