Grails 跨多个域类的过滤和排序
我正在使用 grails，但无法找到跨不同域的连接和排序的适当语法。例如，在下面的示例中，我想检索来自（例如）伦敦的所有作者按标题排序的图书数据页。我更喜欢使用 createCriteria，但如果需要，我会使用另一种技术。
class Location {
String city
static hasMany = [authors: Author]
}
class Author {
String name
static belongsTo = [location: Location]
static hasMany = [books: Book]
}
class Book {
String title
static belongsTo = [author: Author]
}
为了澄清，我想要实现的是获得一个图书域类的列表，该列表相当于像
Select Book.title
From Book
Inner Join Author
On Author.name = Book.authorName
Inner Join Location
On Location.city = Author.homeCity
Where Location.city = 'London'
Order by Book.title
“谢谢”这样的东西
I am using grails and I am having trouble finding the appropriate syntax for joining and ordering across different domains. For example, given the example below, I would like to retrieve a page of book data sorted by title for all authors that come from (eg) London. I have a preference for using createCriteria, but will use another technique if needed.
class Location {
String city
static hasMany = [authors: Author]
}
class Author {
String name
static belongsTo = [location: Location]
static hasMany = [books: Book]
}
class Book {
String title
static belongsTo = [author: Author]
}
To clarify, what I want to achieve would be to get a list of book domain classes that is equivalent to something like
Select Book.title
From Book
Inner Join Author
On Author.name = Book.authorName
Inner Join Location
On Location.city = Author.homeCity
Where Location.city = 'London'
Order by Book.title
Thanks
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要创建更复杂的数据库查询，您可以使用 [criteria 对象][1] 或 [Hibernate 查询语言 (HQL)][2]。第二种方式更强大，但不太舒服。
[1]: http ://grails.org/doc/latest/guide/5.%20Object%20Relational%20Mapping%20(GORM).html#5.4.2 标准
[2]：http://grails.org/doc/latest/guide/ 5.%20Object%20Relational%20Mapping%20(GORM).html#5.4.3 Hibernate 查询语言 (HQL)
For creating more complex database queries you can use [criteria objects][1] or [Hibernate Query Language (HQL)][2]. Second way is more powerful but less comfortable.
[1]: http://grails.org/doc/latest/guide/5.%20Object%20Relational%20Mapping%20(GORM).html#5.4.2 Criteria
[2]: http://grails.org/doc/latest/guide/5.%20Object%20Relational%20Mapping%20(GORM).html#5.4.3 Hibernate Query Language (HQL)