public function isValid()
{
// This is a last line of defense against storing invalid data.
// It can be used to check validity, as an alternative to doing so
// in prepareSave().
//
// Checking here has the advantage that this is ALWAYS called before
// the content is saved to the database, no matter whether the content
// was edited, imported, restored, or what.
//
// The downside is that it's too late here for meaningful interaction
// with the user, we can just abort the save operation, casing an internal
// error.
return parent::isValid();
}
