仅在建立关系后保留 Grails 域

Question

我想知道是否可以创建一个 grails 域对象，但只让它在命令上持久存在，而不是在我们对其进行操作时。

更准确地说，这是我现在要做的：

Foo foo = new Foo(name:"asdf")
Bar bar = new Bar(name:"gzxj")
bar.save() // persist here 
foo.save() // persist here
foo.addToBars(bar) //  now I have to build the relationship

我想要的：

Foo foo = new Foo(name:"asdf")
Bar bar = new Bar(name:"gzxj")
foo.addToBars(bar) //  just build the relationship
bar.save() // would be great to ignore this step
foo.save() // can I now atomically build both objects and create the relationships?

我的印象是，如果要关联的关系很多，后者会快得多。我真的只想要 NoSQL 吗？

Answer 1

这完全有可能，这取决于您建立人际关系的方式。真的和你实现的是什么数据库没有关系。

Parent class

class Foo {
    String name

    static hasMany = [bars: Bar]
}

Child class

class Bar { 
    String name

    Foo foo //optional back reference       
    static belongsTo = Foo
}

执行

Foo foo = new Foo(name: 'a')
Bar bar = new Bar(name: 'b')
foo.addToBars(bar)
foo.save()

//or even more terse

Foo foo = new Foo(name: 'c')
foo.addToBars(new Bar(name: 'd'))
foo.save()

关键是 belongsTo，默认为 all 的 cascade。这也可以明确设置：

class Foo {
    String name

    static hasMany = [bars: Bar]

    static mapping = {
        bars cascade: 'all'
    }
}

仅在建立关系后保留 Grails 域

Persist Grails Domains ONLY after Relationship built

grails

grails-orm

gorm-mongodb

*仅*在建立关系后保留 Grails 域

Persist Grails Domains *ONLY* after Relationship built

grails

grails-orm

gorm-mongodb

仅在建立关系后保留 Grails 域

Persist Grails Domains ONLY after Relationship built