Data Validation through Event

InputPanel provides another way of handling input validation through event. The control comes with the ValidateCurrentItem event that can be used for validating user input.

The following image shows validation applied through event.

To implement data validation through event, subscribe the ValidateCurrentItem event of InputPanel and add validation rules in the event handler in code. The following code shows how to apply validation using event. This example uses the sample created in Quick Start.

Visual Basic
C#

Visual Basic

Dim customer As Customer = TryCast(InPanel.CurrentItem, Customer)

If customer IsNot Nothing Then
    Dim errorList = New ObservableCollection(Of ErrorInfo)()

    If customer.Name IsNot Nothing AndAlso String.IsNullOrWhiteSpace _
        (customer.Name.ToString()) Then
        errorList.Add(New ErrorInfo() With {
   .ErrorInputName = "Name",
    .ErrorContent = "This field cannot be empty."
})
    End If
    If customer.Weight > 150 Then
        errorList.Add(New ErrorInfo() With {
    .ErrorInputName = "Weight",
    .ErrorContent = "Value out of range."
})
    End If
    InPanel.ValidationErrors = errorList
    If errorList.Count > 0 Then
        e.Cancel = True
    End If
End If

Customer customer = InPanel.CurrentItem as Customer;

if (customer != null)
{
    var errorList = new ObservableCollection<ErrorInfo>();

    if (customer.Name != null && string.IsNullOrWhiteSpace(
        customer.Name.ToString()))
    {
        errorList.Add(new ErrorInfo { ErrorInputName = "Name",
                      ErrorContent = "This field cannot be empty." });
    }
    if (customer.Weight > 150)
    {
        errorList.Add(new ErrorInfo { ErrorInputName = "Weight",
                      ErrorContent = "Value out of range." });
    }
    InPanel.ValidationErrors = errorList;
    if (errorList.Count > 0)
    {
        e.Cancel = true;
    }
}