Silverlight like Data Validation in WinRT

Written by Jawahar, Syncfusion Inc.

According to a recent MSDN.com forum discussion, Silverlight-like data validation is not available in WinRT. Syncfusion’s editor controls, however, do have built-in options to achieve such data validation. In Silverlight, data is validated by using the IDataErrorInfo interface. With Syncfusion WinRT editors, we use the Syncfusion.UI.Xaml.Controls.Data.IDataValidation interface for data validation.

Consider a simple model class containing the Age property. Let’s say we want to allow values only within the range of 18-80. The following code snippet shows how to implement the IDataValidation interface.

 public class Person : INotifyPropertyChanged, IDataValidation
 {
     private const string error = "Age should be in the range of 18 to 80.";
     private int _age = 25;
     public int Age
     {
         get { return _age; }
         set { _age = value; RaiseNotification("Age");
     }
 }

 #region IDataValidation implementation
 public string Error
 {
     get { return null; }
 }
 public string this[string columnname]
 {
     get
     {
         if (columnname == "Age")
         {
             if (Age < 18 || Age > 80)
            {
                      return error;
            }
     }
    return null;
  }
} 
 #endregion

 #region INotifyPropertyChanged implementation
 public void RaiseNotification(string propertyname)
 {
    if (PropertyChanged != null)
    {
      PropertyChanged(this, new PropertyChangedEventArgs(propertyname));
    }
}
     public event PropertyChangedEventHandler PropertyChanged; 
  #endregion
 }

In the following snippet, the NotifyOnDataErrors property enables data validation in the editors. The PropertyPath property tells the editor what property needs to be validated.

When a value is entered and the tab is clicked, the text box border turns red, indicating an incorrect value. The option for UpdateSourceTrigger when a property changes is not available in WinRT binding, so the value will be updated only when focus is lost.

You can also display a message using the ErrorMessage property.

This will also work for all our other editor controls, like the NumericTextBox control and the DatePicker control.