问题描述
如何从一个特定作者中选择所有项目?可能这样吗?或者如果我想要许多项目类型和项目包(项目有很多项目),我如何编辑实体?
How can I select all items from one specific author ? Its possible this way ? Or how can I edit entities if I want many item types and item packages (item has many items) too ?
项目
/**
* @ORM\Table()
* @ORM\Entity
* @ORM\InheritanceType("JOINED")
* @ORM\DiscriminatorColumn(name="discr", type="string")
* @ORM\DiscriminatorMap({
* "cd" = "ItemCD",
* "dvd" = "ItemDVD",
* "pack" = "ItemPack",
* })
*/
class Item
{
/**
* @ORM\Column(name="id", type="integer", nullable=false)
* @ORM\Id
* @ORM\GeneratedValue(strategy="IDENTITY")
*/
private $id;
/**
* @ORM\Column(name="name", type="string", length=250, nullable=false)
*/
private $name;
}
ItemCD
/**
* @ORM\Table()
* @ORM\Entity
*/
class ItemCD extends Item
{
/**
* @ORM\ManyToOne(targetEntity="Author", inversedBy="item")
* @ORM\JoinColumn(name="author_id", referencedColumnName="id")
*/
private $author;
}
ItemDVD
/**
* @ORM\Table()
* @ORM\Entity
*/
class ItemDVD extends Item
{
/**
* @ORM\ManyToOne(targetEntity="Author", inversedBy="item")
* @ORM\JoinColumn(name="author_id", referencedColumnName="id")
*/
private $author;
}
ItemPack
/**
* @ORM\Table()
* @ORM\Entity
*/
class ItemPack extends Item
{
/**
* @ORM\ManyToMany(targetEntity="Item", inversedBy="item")
* @ORM\JoinTable()
*/
private $items;
}
作者
/**
* @ORM\Table()
* @ORM\Entity
*/
class Author
{
/**
* @ORM\Column(name="id", type="integer", nullable=false)
* @ORM\Id
* @ORM\GeneratedValue(strategy="IDENTITY")
*
*/
private $id;
/**
* @ORM\Column(name="name", type="string", length=250, nullable=false)
*/
private $name;
}
推荐答案
必须查询特定元素。这是一个已知的(和想要的)限制,因为DQL是一种静态类型的语言:参见
You will have to query for specific elements. This is a known (and wanted) limitation, since DQL is a static typed language: see http://www.doctrine-project.org/jira/browse/DDC-16
相关:
使用解决方法处理此问题的方法是在DQL中使用2个子查询:
A way of handling this with a workaround is using 2 subqueries in your DQL:
SELECT
i
FROM
Item i
WHERE
i.id IN(
SELECT
i2.id
FROM
ItemDvd i2
WHERE
i2.author = :author
)
OR
i.id IN(
SELECT
i3.id
FROM
ItemCd i3
WHERE
i3.author = :author
)
您可以看到,您必须手动提取每个可能的子类型的标识符。
As you can see you have to extract the identifiers for each possible subtype manually.
编辑:从给定的作者获取所有包连同单个DVD或CD),查询变得更糟:
to get all the packs from a given author (along with single DVDs or CDs), the query becomes even worse:
SELECT
i
FROM
Item i
WHERE
i.id IN(
SELECT
i2.id
FROM
ItemDvd i2
WHERE
i2.author = :author
)
OR
i.id IN(
SELECT
i3.id
FROM
ItemCd i3
WHERE
i3.author = :author
)
OR
i.id IN(
SELECT
i4.id
FROM
ItemPack i4
JOIN
i4.items i5
WHERE
i5.id IN (
SELECT
i6.id
FROM
Item i6
WHERE
i6.id IN(
SELECT
i7.id
FROM
ItemDvd i7
WHERE
i7.author = :author
)
OR
i6.id IN(
SELECT
i8.id
FROM
ItemCd i8
WHERE
i8.author = :author
)
)
)
这篇关于在歧视表中的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持!