As a note, if you return false in the HasErrors property, the binding will act as if there were no errors, even if they exists. <\/p>\n

How to use it ?<\/h3>\n

With the traditionnal IDataErrorInfo, you have to set to true the ValidatesOnDataErrors property on each binding to your object. There is nothing really new under the sun because this time you have to set the ValidatesOnNotifyDataErrors property to true<\/strong>. <\/p>\n

In the linked demo project I create a form which display the properties of an object named ‘Person’. Here is how the validation with INotifyDataErrorInfo is enabled in the Binding:
\n[xml] [\/xml]<\/p>\n

The binding will then register itself for the ErrorsChanged event of the binded Person. Eeach time this event is raised for the binded property, the controls will dress itself to display an error. As pointed out before, this is done only if the HasErrors is set to true.<\/strong><\/p>\n

I have implemented a delay in the validation of the Person class. The validations occured after each set of any properties but it is delayed by ‘WaitSecondsBeforeValidation’ seconds.<\/p>\n

I also maintain a dictionary of all the errors by property name and use it to provide them via the GetErros methods. The HasErrors property returns true if this any error exists in this dictionary. Here is the code for this basic implementation:
\n[csharp]public System.Collections.IEnumerable GetErrors(string propertyName)
\n{
\n List errorsForName;
\n _errors.TryGetValue(“Name”, out errorsForName);
\n return errorsForName;
\n}<\/p>\n

public bool HasErrors
\n{
\n get { return _errors.Values.FirstOrDefault(l => l.Count > 0) != null; }
\n}<\/p>\n

private Dictionary> _errors =
\n new Dictionary>();<\/p>\n

private void Validate()
\n{
\n Task waitTask = new Task(() => Thread.Sleep(
\n TimeSpan.FromSeconds(WaitSecondsBeforeValidation)));
\n waitTask.ContinueWith((_) => RealValidation());
\n waitTask.Start();
\n}<\/p>\n

private object _lock = new object();
\nprivate void RealValidation()
\n{
\n lock (_lock)
\n {
\n \/\/Validate Name
\n List errorsForName;
\n if (!_errors.TryGetValue(“Name”, out errorsForName))
\n errorsForName = new List();
\n else errorsForName.Clear();<\/p>\n

if (String.IsNullOrEmpty(Name))
\n errorsForName.Add(“The name can’t be null or empty.”);<\/p>\n

_errors[“Name”] = errorsForName;
\n if (errorsForName.Count > 0) RaiseErrorsChanged(“Name”);<\/p>\n

\/\/Validate Age
\n List errorsForAge;
\n if (!_errors.TryGetValue(“Age”, out errorsForAge))
\n errorsForAge = new List();
\n else errorsForAge.Clear();<\/p>\n

if (Age <= 0)\n errorsForAge.Add(\"The age must be greater than zero.\");\n\n _errors[\"Age\"] = errorsForAge;\n if (errorsForAge.Count > 0) RaiseErrorsChanged(“Age”);
\n }
\n[\/csharp]<\/p>\n

Finally, I have created a RaiseErrorsChanged method which ease the raising of Validations event errors:
\n[csharp] public event EventHandler ErrorsChanged;
\n public void RaiseErrorsChanged(string propertyName)
\n {
\n EventHandler handler = ErrorsChanged;
\n if (handler == null) return;
\n var arg = new DataErrorsChangedEventArgs(propertyName);
\n handler.Invoke(this, arg);
\n }
\n[\/csharp]<\/p>\n