Yii2 ActiveRecord save()往表中插入数据不成功，是什么原因？ [ 2.0 版本 ]

$history = new History();
$history->uid = $uid;
$history->type = $type;
$history->ceid = $ceid;
$history->duration = $playedduration;
$history->dateline = time();
if($history->validate()&&$history->save()){
    return JsonWidget::widget(array(
        'success'=>true,
        'message'=>'',
        'data'=>array('hid'=>$history->hid)
    ));
}else{
    return JsonWidget::widget(array(
        'success'=>false,
            'message'=>'',
            'data'=>array()
    ));  
}