IRuleSource Interface

Declares members implemented by custom Validation Rule Sources.

Namespace: DevExpress.Persistent.Validation

Assembly: DevExpress.Persistent.Base.v19.2.dll

Declaration

C#

public interface IRuleSource

VB.NET

Public Interface IRuleSource

Remarks

There are several ways in which you can declare a Validation Rule. A typical way is to decorate a target business class with a Validation Rule Attribute. However, the Validation Module allows you to define a custom Validation Rule Source by implementing the IRuleSource interface in a business class. Classes that implement the IRuleSource interface are considered to be Validation Rule Sources by XAF, and are used to provide custom Validation Rules when the application is started. Custom Validation Rule Sources are collected automatically, and no registration is necessary.

The IRuleSource interface exposes two members. The IRuleSource.Name property should return the unique name of the custom Validation Rule Source. The IRuleSource.CreateRules method should instantiate custom Validation Rules.

One of the scenarios in which you may need to implement a custom Validation Rule Source is implementing Validation Rules stored in the database. This approach can be used when you need to frequently customize Validation Rules in a deployed application, but you cannot redeploy the application or customize its Application Model. The following example illustrates this scenario.

Tip

A complete sample project is available in the DevExpress Code Examples database at https://supportcenter.devexpress.com/ticket/details/e729/how-to-create-validation-rules-stored-in-the-database.

The RuleRequiredFieldPersistent class demonstrated in this example is a regular business class. However, the class implements the IRuleSource interface, and is used to create and store RuleRequiredField Validation Rules in the database. In the IRuleSource.CreateRules method a RuleRequiredField Validation Rule is instantiated, based on the values of the RuleRequiredFieldPersistent class’ public properties. The RuleRequiredFieldPersistent class is marked with the DefaultClassOptionsAttribute, so that end-users can manually create Validation Rules via a corresponding List View.

C#

[DefaultClassOptions]
public class RuleRequiredFieldPersistent : BaseObject, 
    DevExpress.Persistent.Validation.IRuleSource {
    public RuleRequiredFieldPersistent(Session session) : base(session) { }
    public string RuleName {
        get { return GetPropertyValue<string>(nameof(RuleName)); }
        set { SetPropertyValue(nameof(RuleName), value); }
    }
    public string CustomMessageTemplate {
        get { return GetPropertyValue<string>(nameof(CustomMessageTemplate)); }
        set { SetPropertyValue(nameof(CustomMessageTemplate), value); }
    }
    public bool SkipNullOrEmptyValues {
        get { return GetPropertyValue<bool>(nameof(SkipNullOrEmptyValues)); }
        set { SetPropertyValue(nameof(SkipNullOrEmptyValues), value); }
    }
    public string Id {
        get { return GetPropertyValue<string>(nameof(Id)); }
        set { SetPropertyValue(nameof(Id), value); }
    }
    public bool InvertResult {
        get { return GetPropertyValue<bool>(nameof(InvertResult)); }
        set { SetPropertyValue(nameof(InvertResult), value); }
    }
    public string ContextIDs {
        get { return GetPropertyValue<string>(nameof(ContextIDs)); }
        set { SetPropertyValue(nameof(ContextIDs), value); }
    }
    public string Property {
        get { return GetPropertyValue<string>(nameof(Property)); }
        set { SetPropertyValue(nameof(Property), value); }
    }
    [Persistent("ObjectType")]
    protected string ObjectType {
        get {
            if(ObjectTypeCore != null) {
                return ObjectTypeCore.FullName;
            }
            return "";
        }
        set { ObjectTypeCore = ReflectionHelper.FindType(value); }
    }
    [NonPersistent]
    [TypeConverter(typeof(DevExpress.Persistent.Base.LocalizedClassInfoTypeConverter))]
    public Type ObjectTypeCore {
        get { return GetPropertyValue<Type>(nameof(ObjectTypeCore)); }
        set { SetPropertyValue(nameof(ObjectTypeCore), value); }
    }
    #region IRuleSource Members
    public System.Collections.Generic.ICollection<IRule> CreateRules() {
        System.Collections.Generic.List<IRule> list = new System.Collections.Generic.List<IRule>();
        RuleRequiredField rule = new RuleRequiredField();
        rule.Properties.SkipNullOrEmptyValues = this.SkipNullOrEmptyValues;
        rule.Properties.Id = this.Id;
        rule.Properties.InvertResult = this.InvertResult;
        rule.Properties.CustomMessageTemplate = this.CustomMessageTemplate;
        rule.Properties.TargetContextIDs = new ContextIdentifiers(this.ContextIDs);
        rule.Properties.TargetType = this.ObjectTypeCore;
        if(rule.Properties.TargetType != null) {
            foreach(PropertyInfo pi in rule.Properties.TargetType.GetProperties()) {
                if(pi.Name == this.Property) {
                    rule.Properties.TargetPropertyName = pi.Name;
                }
            }
        }
        for(int i = Validator.RuleSet.RegisteredRules.Count - 1; i >= 0; i--) {
            if(Validator.RuleSet.RegisteredRules[i].Id == this.Id) {
                Validator.RuleSet.RegisteredRules.RemoveAt(i);
            }
        }
        list.Add(rule);
        return list;
    }
    [Browsable(false)]
    public string Name {
        get { return this.RuleName; }
    }
    #endregion
}

VB.NET

<DefaultClassOptions> _
Public Class RuleRequiredFieldPersistent
    Inherits BaseObject
    Implements DevExpress.Persistent.Validation.IRuleSource
    Public Sub New(ByVal session As Session)
        MyBase.New(session)
    End Sub
    Public Property RuleName() As String
        Get
            Return GetPropertyValue(Of String)(NameOf(RuleName))
        End Get
        Set(ByVal value As String)
            SetPropertyValue(NameOf(RuleName), value)
        End Set
    End Property
    Public Property CustomMessageTemplate() As String
        Get
            Return GetPropertyValue(Of String)(NameOf(CustomMessageTemplate))
        End Get
        Set(ByVal value As String)
            SetPropertyValue(NameOf(CustomMessageTemplate), value)
        End Set
    End Property
    Public Property SkipNullOrEmptyValues() As Boolean
        Get
            Return GetPropertyValue(Of Boolean)(NameOf(SkipNullOrEmptyValues))
        End Get
        Set(ByVal value As Boolean)
            SetPropertyValue(NameOf(SkipNullOrEmptyValues), value)
        End Set
    End Property
    Public Property Id() As String
        Get
            Return GetPropertyValue(Of String)(NameOf(Id))
        End Get
        Set(ByVal value As String)
            SetPropertyValue(NameOf(Id), value)
        End Set
    End Property
    Public Property InvertResult() As Boolean
        Get
            Return GetPropertyValue(Of Boolean)(NameOf(InvertResult))
        End Get
        Set(ByVal value As Boolean)
            SetPropertyValue(NameOf(InvertResult), value)
        End Set
    End Property
    Public Property ContextIDs() As String
        Get
            Return GetPropertyValue(Of String)(NameOf(ContextIDs))
        End Get
        Set(ByVal value As String)
            SetPropertyValue(NameOf(ContextIDs), value)
        End Set
    End Property
    Public Property [Property]() As String
        Get
            Return GetPropertyValue(Of String)(NameOf(Property))
        End Get
        Set(ByVal value As String)
            SetPropertyValue(NameOf(Property), value)
        End Set
    End Property
    <Persistent("ObjectType")> _
    Protected Property ObjectType() As String
        Get
            If ObjectTypeCore IsNot Nothing Then
                Return ObjectTypeCore.FullName
            End If
            Return ""
        End Get
        Set(ByVal value As String)
            ObjectTypeCore = ReflectionHelper.FindType(value)
        End Set
    End Property
    <NonPersistent(), TypeConverter(GetType( _
    DevExpress.Persistent.Base.LocalizedClassInfoTypeConverter))> _
    Public Property ObjectTypeCore() As Type
        Get
            Return GetPropertyValue(Of Type)(NameOf(ObjectTypeCore))
        End Get
        Set(ByVal value As Type)
            SetPropertyValue(NameOf(ObjectTypeCore), value)
        End Set
    End Property
    #Region "IRuleSource Members"
        Public Function CreateRules() As System.Collections.Generic.ICollection(Of IRule) _
        Implements DevExpress.Persistent.Validation.IRuleSource.CreateRules
            Dim list As New System.Collections.Generic.List(Of IRule)()
            Dim rule As New RuleRequiredField()
            rule.Properties.SkipNullOrEmptyValues = Me.SkipNullOrEmptyValues
            rule.Properties.Id = Me.Id
            rule.Properties.InvertResult = Me.InvertResult
            rule.Properties.CustomMessageTemplate = Me.CustomMessageTemplate
            rule.Properties.TargetContextIDs = New ContextIdentifiers(Me.ContextIDs)
            rule.Properties.TargetType = Me.ObjectTypeCore
            If rule.Properties.TargetType IsNot Nothing Then
                For Each pi As PropertyInfo In rule.Properties.TargetType.GetProperties()
                    If pi.Name = Me.Property Then
                        rule.Properties.TargetPropertyName = pi.Name
                    End If
                Next pi
            End If
            For i As Integer = Validator.RuleSet.RegisteredRules.Count - 1 To 0 Step -1
                If Validator.RuleSet.RegisteredRules(i).Id = Me.Id Then
                    Validator.RuleSet.RegisteredRules.RemoveAt(i)
                End If
            Next i
            list.Add(rule)
            Return list
        End Function
        <Browsable(False)> _
        Public ReadOnly Property Name() As String _
        Implements DevExpress.Persistent.Validation.IRuleSource.Name
            Get
                Return Me.RuleName
            End Get
        End Property
    #End Region
End Class