protected bool Validate()
{
var previousResults = _validationResults;
var validator = ProvideValidator();
_validationResults = validator.Validate(this);
// raise errors changed event for union set of previous and current results
// so a change notification is raised for each affected property
var propertiesInError =
previousResults
.GetPropertiesInError()
.Union(_validationResults.GetPropertiesInError())
.Distinct();
// HasErrors must be true before raising the ErrorsChanged event, otherwise WPF will ignore the errors !!
// Thx to http://stackoverflow.com/a/24837028 for this hint ;-)
IsValid = _validationResults.IsValid;
HasErrors = !IsValid;
foreach (var property in propertiesInError)
{
RaiseErrorsChanged(property);
}
_validationSubject.OnNext(_validationResults);
return(_validationResults.IsValid);
}