yii save でデータを保存できない場合はどうすればよいですか?

public function actionIndex()
{
    $session = Yii::$app->session;
    Yii::$app->response->format=Response::FORMAT_JSON;
    $model = new PostSendInfo();
//        $post = Yii::$app->request->post();
    $post=['company_name'=>'123','mobile_phone'=>12,'sender_dep'=>'2323'];
    if ($post) {
        $model->login_id = $session['login_id'];
        $model->case_id  = "1";
        $model->ems_id   = "2";
        $model->create_time = date('Y-m-d H:i:s',time());
        $model->setAttributes($post);
        if($model->save()){
            return "保存成功！";
        }
        return "保存失败！";
    }
    return "保存失败！";
}