RadComboBox with ValidateOnDataError (MVVM)

[Dario]

Hi to all,
I have a RadComboBox controlo that has 

SelectedItem={Binding MyItemSelected, ValidatesOnDataError=True, Mode=TwoWay}

MyViewModel has "ViewModelBase" class linked that keep "Error System"

public class ViewModelBase : INotifyPropertyChanged, IDataErrorInfo
    {
        #region private variables

        private bool _hasErrors;

        #endregion

        #region public properties

        public bool HasErrors
        {
            get { return _hasErrors; }
            set
            {
                _hasErrors = value;
                NotifyPropertyChanged("HasErrors");

            }
        }

        #endregion

        #region INotifyPropertyChanged Members
        public event PropertyChangedEventHandler PropertyChanged;
        protected void NotifyPropertyChanged(string propertyName)
        {
            if (PropertyChanged != null)
            {
                PropertyChanged(this,
                new PropertyChangedEventArgs(propertyName));
            }

            //Aggiorna lo stato di errore dell'intera entità
            if (propertyName != "HasErrors")
                HasErrors = (_dataErrors.Count > 0);
        }
        #endregion

        #region IDataErrorInfo Members
        private string _dataError = string.Empty;
        string IDataErrorInfo.Error
        {
            get { return _dataError; }
        }
        protected Dictionary<string, string> _dataErrors = new Dictionary<string, string>();

        string IDataErrorInfo.this[string columnName]
        {
            get
            {
                if (_dataErrors.ContainsKey(columnName))
                    return _dataErrors[columnName];
                else
                    return null;
            }
        }

        protected void UpdateError(string columnName, string errorMessage)
        {
            _dataErrors[columnName] = errorMessage;
        }

        protected void RemoveErrors(string columnName)
        {
            if (_dataErrors.ContainsKey(columnName))
                _dataErrors.Remove(columnName);
        }

        #endregion
    }

If I use this method with a TextBox control, I obtain correctly "classic red waring", but with RadComboBox not appears nothing.
How can I keep this case?

[Vladi]

Hi Dario,

In order to achieve validation when using RadComboBox I would suggest you to see our online demo that demonstrates how to achieve the desired behavior.

The online demo is available here.

All the best,
Vladi
the Telerik team

[Dario]

Thank you for support.