How to: Implement a Custom Validation Procedure

• Jun 07, 2019

The following example shows how to handle the BaseEdit.Validate event to implement a custom validation procedure.

The image below shows the result:

XAML

<dxe:TextEdit x:Name="dxTextEdit"
          ValidateOnTextInput="False"
          Validate="dxTextEdit_Validate"/>

C#

private void dxTextEdit_Validate(object sender, DevExpress.Xpf.Editors.ValidationEventArgs e) {
    // e.Value - the processed input value
    if (e.Value == null) return;
    if (e.Value.ToString().Length > 4) return;
    // Set the e.IsValid property to 'false' if the input value is invalid
    e.IsValid = false;
    // Specifies the error icon type
    e.ErrorType = DevExpress.XtraEditors.DXErrorProvider.ErrorType.Information;
    // Specifies the error text
    e.ErrorContent = "User ID is less than five symbols. Please correct.";
}

VB.NET

Private Sub dxTextEdit_Validate(ByVal sender As Object, ByVal e As DevExpress.Xpf.Editors.ValidationEventArgs)
    ' e.Value - the processed input value
    If e.Value Is Nothing Then Return
    If e.Value.ToString().Length > 4 Then Return
    ' Set the e.IsValid property to 'false' if the input value is invalid
    e.IsValid = False
    ' Specifies the error icon type
    e.ErrorType = DevExpress.XtraEditors.DXErrorProvider.ErrorType.Information
    ' Specifies the error text
    e.ErrorContent = "User ID is less than five symbols. Please correct."
End Sub