Doctrine 2 限制与 DQL 的关联

Doctrine 2 Restricting Associations with DQL(Doctrine 2 限制与 DQL 的关联)

问题描述

在 Doctrine 2.1 中似乎有一个问题，返回子集并不容易为协会收集.

There seems to be an over sight in Doctrine 2.1 where it isn't easy to return a subset collection for an association.

http://www.doctrine-project.org/docs/orm/2.1/en/reference/limitations-and-known-issues.html#restricting-associations

文档建议编写存储库查找方法，这是有道理的，因为这是我想做的第一件事.

The docs recommend to write a repository find method, which makes sense because that was the first thing I though of doing.

但是，如果没有对实体内的 EntityManager 的引用，我看不出您将如何检索关联的存储库，这似乎违背了将域与数据库分离的意义?

However without having a reference to the EntityManager within an Entity I can't see how you would retrieve the association's Repository and this seems to defeat the point of separating the Domain from the Database?

是否有针对此问题的推荐策略?

Is there a recommended strategy for this problem?

这是我对他们建议的解决方案的解释.

Here is my interpretation of their suggested solution.

class Category
{
    protected $id;
    protected $articles; // PesistentCollection
    protected $em; // The EntityManager from somewhere?

    public function getVisableArticles()
    {
        return $this->em->getRepository('Article')
                    ->getVisibleByCategory($this);
    }
}

推荐答案

1. 在实体中使用 entitymanager 在任何情况下都不是一件好事(改为注入您的存储库)
2. 类别不是文章的唯一根，因为它无法确定您需要哪些文章，因此您需要一个文章存储库.

我会怎么做:

class Category
{
    protected $id;
    protected $articles; // PesistentCollection

    public function getVisableArticles(IArticleRepository $articleRepository)
    {
        return $articleRepository->getVisibleByCategory($this);
    }
}

interface IArticleRepository
{
    function getVisibleByCategory(Category $category);
}

您的学说的存储库将实现 IArticleRepository，而该类将不知道您的数据存储/学说的任何信息.

Your doctrine's repository would implement IArticleRepository and the class won't know anything about your data storage/doctrine.

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