INotifyDataErrorInfoをサポートするBindableBase

ValidatableModelBase.cs

/// <summary>
/// INotifyDataErrorInfoをサポートするBindableBase
/// </summary>
class ValidatableModelBase : BindableBase, INotifyDataErrorInfo
{
    private ErrorsContainer<string> _errors;

    public event EventHandler<DataErrorsChangedEventArgs> ErrorsChanged;

    public IEnumerable GetErrors(string propertyName)
    {
        return _errors.GetErrors(propertyName);
    }

    public bool HasErrors
    {
        get { return _errors.HasErrors; }
    }

    public ValidatableModelBase()
    {
        _errors = new ErrorsContainer<string>(OnErrorsChanged);
    }

    private void OnErrorsChanged([CallerMemberName] string propertyName = null)
    {
        ErrorsChanged?.Invoke(this, new DataErrorsChangedEventArgs(propertyName));
    }

    protected void ValidateProperty(object value, [CallerMemberName] string propertyName = null)
    {
        var context = new ValidationContext(this)
        {
            MemberName = propertyName
        };
        var validationErrors = new List<ValidationResult>();
        if (!Validator.TryValidateProperty(value, context, validationErrors))
        {
            _errors.SetErrors(propertyName, validationErrors.Select(error => error.ErrorMessage));
        }
        else
        {
            _errors.ClearErrors(propertyName);
        }
    }
}

thanks: https://qiita.com/Koki_jp/items/ae00c525728b81f302b8