我有一个Blog域类,其中包含许多消息:
class Blog {
String description
static hasMany = [messages : Message]
static belongsTo = [owner : User]
static constraints = {
description blank: true, nullable: true
}
}
class Message {
String content
String title
User author
Date dateCreated
Date lastUpdated
static hasMany = [comments : Comment]
static constraints = {
content blank: false
author nullable: false
title nullable: false, blank: false
}
static mapping = {
content type: "text"
sort dateCreated: 'desc'
}
}
消息还在应用程序的其他地方使用,因此关联是单向的。如何获得20条最新博客消息(按创建日期排序)?所谓最新博客消息,是指与任何博客相关的20条最新消息。
最佳答案
class Blog {
...
...
static hasMany [messages: BlogMessages]
...
...
}
class Message {
...
// exactly like you have it
...
}
class BlogMessage extends Message {
Blog blog
}
然后,您可以像这样获取...
BlogMessage.list([max:20])
关于grails - Grails GORM/HQL-从关联中检索数据,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/5648735/