Grails 数据绑定疑问

Question

   Class Carro {
String name
String marca
String matricula

} 

Class CarroMovel{

String pro1
String prop2
String prop3

Carro carro

static hasMany = [ carros: Carro]

}

---

 def save2 = {

                def carroInstance = new Carro()
                def carroMovelInstance = new CarroMovel()

                carroInstance.name = params.name
                carroInstance.marca = params.marca
                carroInstance.matricula = params.matricula

                carroMovelInstance.prop1 = params.carroMovel.prop1
                carroMovelInstance.prop2 = params.carroMovel.prop2
                carroMovelInstance.prop3 = params.carroMovel.prop3

                carroInstance.save()
                carroMovelInstance.carro = carroInstance
                carroMovelInstance.save()                 

            }

CarroInstance 正在保存，但 carroMovelInstance 没有。我想不明白。任何帮助将不胜感激。

Answer 1

Grooveek is correct，因为您从未调用过carroMovelInstance.save()。

但是，您可能更简单地利用 Grails 的数据绑定，而不是不必要地创建关联并手动绑定参数。

// Update your Carro domain.
def Carro {
    String name
    String marca
    String matricula

    // will cause persistence operations to cascade from CarroMovel to Carro
    static belongsTo = CarroMovel
}

// Update your save2 action.
// By passing 'params' to the CarroMovel constructor, Grails will bind request
// parameters to domain properties of the same name; it even works with associations!
def save2 = {
    def carroMovelInstance = new CarroMovel(params)
    if(carroMovelInstance.validate) {
        carroMovelInstance.save()
    }
}

阅读 Grails Data Binding，尤其是关于关联的部分。此外，阅读 "Understanding Cascading Updates and Deletes" 以了解对父域对象的 save() 调用将如何（或不会）级联到关联的域对象。

Answer 2

您从不要求 carroMovelInstance 保存... carro 实例也没有引用 carroMovel 实例，因此没有级联保存