Symfony2和Doctrine $ em->坚持VS $ em-> merge

Question

您好我有关于主义之间的区别一个快速的问题merge()和persist()

我有一NewsBuilder节课:

• 这需要一个新闻实体并检查它是否存在于数据库中,如果它存在,则将实体的值设置为传递的数据并返回实体.
• 如果它不存在,则创建新的新闻实体设置数据并
  返回实体

namespace FantasyPro\DataBundle\Builder;

use FantasyPro\DataBundle\Entity\News;
use FantasyPro\DataBundle\Helpers\DateHelper;

class NewsBuilder
{
    /**
     * @var DateHelper $dateHelper
     */
    private $dateHelper;

    public function __construct( DateHelper $dateHelper )
    {
        $this->dateHelper = $dateHelper;
    }

    public function buildNews( $currentNews = null, $news)
    {
        if ( ! $currentNews) { // check if we already have the news stored
            $currentNews = new News();
        }
        $currentNews->setNewsID( $news['NewsID'] );
        $currentNews->setTitle( $news['Title'] );
        $currentNews->setUpdated( $this->dateHelper->parseDate( $news['Updated'] ) );
        $currentNews->setUrl( $news['Url'] );
        $currentNews->setContent( $news['Content'] );
        $currentNews->setSource( $news['Source'] );
        $currentNews->setTermsOfUse( $news['TermsOfUse'] );
        $currentNews->setTeam( $news['Team'] );
        $currentNews->setPlayerID( $news['PlayerID'] );

        return $currentNews;
    }
}

这是由一个NewsPersister类使用

这会通过FindByOne()传递我正在解析的数据的id来检查我的repo .

    namespace FantasyPro\DataBundle\Persisters;

    use Doctrine\ORM\EntityManager;
    use FantasyPro\DataBundle\Builder\NewsBuilder;
    use FantasyPro\DataBundle\Entity\News;

    class NewsPersister {

        /**
         * @var EntityManager $em
         */
        private $em;
        /**
         * @var NewsBuilder $builder
         */
        private $builder;

        public function __construct( EntityManager $em, NewsBuilder $builder )
        {
            $this->em      = $em;
            $this->builder = $builder;
        }

        public function Persist($news){
            //get the news repository
            $repo = $this->em->getRepository( 'DataBundle:News' );

            // get the current news from the db
            $criteria    = array(
                'newsID' => $news['NewsID']
            );

            /**
             * @var News $currentNews
             */
            $currentNews = $repo->FindOneBy( $criteria );

            //todo: use a logger to write this data to file

            //build the news entity
            $currentNews = $this->builder->buildNews( $currentNews, $news );

            //persist the team
            $this->em->persist( $currentNews );
        }
    }

她的问题是:可以放弃FindByOne()声明而只是使用$em->merge()而不是$em->persist()

我$em->merge是否认为根据id是否存在而将实体设置为更新或插入？我多打电话给他回购不必要？

Answer 1

不,你不能删除

不同之处在于您对实体的影响.

Persist接受实体实例,将其添加到持久性上下文并使其受管理,因此所有其他更新将由实体管理器管理.

合并将创建实体的新实例,从提供的实体复制状态,并将管理新的副本,但不会管理传递的实体,因此实体管理器不会缓存进一步的更改

通过你的例子:如果你将坚持更改为合并,那么它将没有任何区别.因此合并将持续做同样的工作.通常,当您有分离的实体或未序列化(即来自缓存)时,您应该使用merge