的Grails：从HQL到的DetachedCriteria查询

让说我有以下的域模型：的Grails：从HQL到的DetachedCriteria查询

class Book { 
    String title 
    Set authors 

    static hasMany = {authors: Author} 
} 

class Author { 
    String name 
}

的HQL查询来获取给定的标题图书查询作者的集合：

Author.executeQuery("select distinct author from Book as book join book.authors as author where book.name like ?", ["%groovy%"])

但我会能够与DetachedCriteria或类似的（但它可能......？），并没有增加从作者到书的关系相同的结果（否则它会很明显）

来源

2012-01-20 Jean-Baptiste

不幸的是，AFAIK，这个查询是不可能的。这可能与以下丑陋的查询，但：

select author from Author author 
where author.id in (select author2.id from Book book 
        join book.authors as author2 
        where book.name like :bookName)

对于这样一个简单的，非动态组成的查询，我要和你HQL查询坚持。如果你确实需要使用的标准，那么这是对应的代码：

Criteria c = session.createCriteria(Author.class, "author"); 
DetachedCriteria dc = DetachedCriteria.forClass(Book.class, "book"); 
dc.createAlias("book.authors", "author2"); 
dc.add(Restrictions.like("book.name", bookName)); 
dc.setProjection(Projections.property("author.id")); 
c.add(Subqueries.propertyIn("author.id", dc); 
List<Author> authors = (List<Author>) c.list();

来源

2012-01-20 14:28:53

这些休眠的标准和查询的DetachedCriteria？不是GORM标准和DetachedCriteria？你有线索如何写与德Grails/GORM标准和DetachedCriteria一样吗？ –

不，我认为GORM只是Hibernate的Java API的封装。 –

这是可以做到与标准或分离标准的一些方法，但因为容易与普通格姆的标准有点它实现了createAlias吩咐的DetachedCriteria不一样的Grails 2.2.2：

Create Alias In Detached Criteria

这里有两种方式：

package bookauthor 

import grails.gorm.DetachedCriteria 
import grails.orm.HibernateCriteriaBuilder 


class MyController { 

def index() { 
    HibernateCriteriaBuilder ac2 = Author.createCriteria() 
    HibernateCriteriaBuilder criteria2 = Author.createCriteria() 

    HibernateCriteriaBuilder criteria = Book.createCriteria() 

    def bookResults = criteria { 
    projections { 
     property 'aut.id' 
    } 
    createAlias('authors', 'aut') 
    like('title', '%Groovy%') 

    } 

    def dc = new DetachedCriteria(Book).build { 
    authors {} 
    like('title', '%Groovy%') 
    } 

    def myList = dc.list().collect { it.authors.collect { author -> author.id} }.flatten() 

    def resultsDetached = criteria2 { 
    'in'('id', myList) 
    } 

    def results = ac2 { 
    'in'('id', bookResults) 
    } 
log.info("RESULTS: " + results) 
log.info("Detached RESULTS: " + resultsDetached) 
} 

}

您将在日志中看到：

bookauthor.MyController - RESULTS: [bookauthor.Author : 1, bookauthor.Author : 3] 
bookauthor.MyController - Detached RESULTS: [bookauthor.Author : 1, bookauthor.Author : 3]

来源

2013-06-24 21:29:00 dkstyle0

的Grails：从HQL到的DetachedCriteria查询

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