RuleObjectExistsAttribute(String, DefaultContexts, String, String) Constructor

Initializes a new instance of the RuleObjectExistsAttribute class.

Namespace: DevExpress.Persistent.Validation

Assembly: DevExpress.Persistent.Base.v18.2.dll


public RuleObjectExistsAttribute(
    string id,
    DefaultContexts targetContexts,
    string criteria,
    string messageTemplate
Public Sub New(
    id As String,
    targetContexts As DefaultContexts,
    criteria As String,
    messageTemplate As String


Type Name Description
String id

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.

DefaultContexts targetContexts

A DefaultContexts enumeration value that specifies a context for checking the current rule. This value is set for the RuleBaseAttribute.TargetContextIDs property.

String criteria

A string value representing the criteria that must be satisfied by the target type objects.

String messageTemplate

A string value representing information defining the current rule. This value is set for the RuleBaseAttribute.CustomMessageTemplate property.


If you are going to use a default message template for the rule, use a constructor without 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.

See Also