Symfony2 Doctrine 从一个类别中获取随机产品
我有以下数据库方案:
table 'products'
id
category_id
当然还有一个类别表,只有一个 id.
and of course a category table, just with an id.
数据看起来像这样:
Products
--------------------
| id | category_id |
--------------------
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 2 |
| 5 | 1 |
--------------------
我想选择一个类别(例如类别 1),因此我在我的产品存储库类中选择该类别中的所有行:
I would like to select a category(for example Category 1), so I select all the rows from that category in my product-repository class:
return $this
->createQueryBuilder('u')
->andWhere('u.category = :category')
->setMaxResults(1)
->setParameter('category', $category->getId())
->getQuery()
->getSingleResult()
;
我现在如何选择随机产品?另外:是否可以通过关系解决这个问题?
How I can select now a random product? Also: Is it possible to solve this via Relationships?
我在实体Category"和Product"之间有一个 OneToMany 关系,所以我也可以通过 category->getProducts()...
I have a OneToMany Relationship between the entities "Category" and "Product", so I could also get all the products via category->getProducts()...
任何帮助都会非常有用,谢谢
Any help would be really useful, thanks
推荐答案
你首先要统计产品的总数,然后生成一个随机偏移量来选择一个随机产品.
You first have to count the total number of products, then generate a random offset to select a random product.
这应该让你开始:
$count = $this->createQueryBuilder('u')
->select('COUNT(u)')
->getQuery()
->getSingleScalarResult();
然后你可以在你的 1 和总行数之间生成一个随机数.
And then you can generate a random number between your 1 and the total number of rows.
return $this->createQueryBuilder('u')
->where('u.category = :category')
->setFirstResult(rand(0, $count - 1))
->setMaxResults(1)
->setParameter('category', $category->getId())
->getQuery()
->getSingleResult()
;
翻译为:
SELECT * FROM products WHERE category_id = ? LIMIT 1, {random offset}
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