使用 GWT + 从集合中选择应用程序引擎日本PA
是否可以搜索集合字段包含特定值的实体？
例如，如果我有一个名为 Item 的实体，并且它包含一个名为categories 的 Collection 字段。
public class Item {
@ManyToMany(cascade = CascadeType.ALL)
private Set<String> categories = new HashSet<String>();
}
所以我想做的是选择包含“蓝色”类别的每个项目。
我尝试了以下查询：
SELECT o FROM Item AS o WHERE o.categories = :category
SELECT o FROM Item AS o WHERE o.categoriesKeys = :category
SELECT o FROM Item AS o WHERE :category MEMBER OF o.categories
但事实并非如此不工作。
Is it possible to search for entities where a Collection field contains a specific value?
For example if I have an entity named Item and it contains a Collection field named categories.
public class Item {
@ManyToMany(cascade = CascadeType.ALL)
private Set<String> categories = new HashSet<String>();
}
So what I want to do is to select every item that contains the category "blue".
I tried the following queries:
SELECT o FROM Item AS o WHERE o.categories = :category
SELECT o FROM Item AS o WHERE o.categoriesKeys = :category
SELECT o FROM Item AS o WHERE :category MEMBER OF o.categories
But it doesn't work.
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评论（1）
这就是您需要的： http:// /docs.jboss.org/hibernate/core/3.3/reference/en/html/objectstate.html#objectstate-filtering
this is wat you need: http://docs.jboss.org/hibernate/core/3.3/reference/en/html/objectstate.html#objectstate-filtering