grails - 跨多个域类的Grails过滤和排序

Question

我正在使用grails，在查找用于跨不同域的联接和排序的适当语法时遇到了麻烦。例如，给定以下示例，我想检索来自(例如)伦敦的所有作者的按标题分类的书籍数据页面。我偏爱使用createCriteria，但如有需要，将使用另一种技术。

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]
} 

澄清一下，我想实现的目标是获取与类似

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

Answer 1

要创建更复杂的数据库查询，可以使用[条件对象] [1]或[休眠查询语言(HQL)] [2]。第二种方法功能更强大，但不太舒适。

[1]:http://grails.org/doc/latest/guide/5.%20Object%20Relational%20Mapping%20(GORM).html#5.4.2条件

[2]:http://grails.org/doc/latest/guide/5.%20Object%20Relational%20Mapping%20(GORM).html#5.4.3休眠查询语言(HQL)