If you have a Column that is bound to a Business Object, and then you wish to display a property of that Object and want to filter the data on another property of that object, you might want to create your own custom object criterion. I have created a sample class that you can use in case you wish to filter on a string property of that object. We will extend the ContainsFilterCriterion since we are supplying the FilterCriterion with a string and looking for instances of that string in other string values.

We will then override the IsMatch(object value) method where we can choose which property of that object we wish to filter on. In this sample, we wish to search for instance of searchedValue in the ChildProperty property of the object of type Child.

C#

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public class CustomObjectCriterion : ContainsFilterCriterion
    {
        public CustomObjectCriterion()
            : base()
        {
        }

        public CustomObjectCriterion(object value)
            : base(value)
        {
        }

        public override bool IsMatch(object value)
        {
            if (value == null)
                return false;

            if (this.Value == null)
                return true;

            string searchedValue = this.Value.ToString().ToLower();

            if (searchedValue.Length == 0)
                return true;

            string strValue = value.ToString().ToLower();

            return (value as Child).ChildProperty.Contains(searchedValue);
        }
    }

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Visual Basic.NET

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Public Class CustomObjectCriterion
    Inherits ContainsFilterCriterion
    Public Sub New()
        MyBase.New()
    End Sub

    Public Sub New(value As Object)
        MyBase.New(value)
    End Sub

    Public Overrides Function IsMatch(value As Object) As Boolean
        If value Is Nothing Then
            Return False
        End If

        If Me.Value Is Nothing Then
            Return True
        End If

        Dim searchedValue As String = Me.Value.ToString().ToLower()

        If searchedValue.Length = 0 Then
            Return True
        End If

        Dim strValue As String = value.ToString().ToLower()

        Return TryCast(value, Child).ChildProperty.Contains(searchedValue)
    End Function
End Class

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