将[hasMany：]引用的数据类型更改为列表？ [英] Changing the data type of the [hasMany:] reference to a list?

问题描述

有没有办法在grails中改变静态hasMany = [myList：Stuff] 定义的数据类型？我试过

Is there a way to change the data type of the static hasMany = [myList: Stuff] definition in grails? I tried

List<Stuff> myList
hasMany = [myList : Stuff]

但我现有的测试开始投掷

but my existing tests started throwing

Stuff._MyContainer_mylistBackref;嵌套的异常是org.hibernate.PropertyValueException：非空属性引用空值或瞬态值

这表明两者不等价他们如何处理的条款。我在这里做错了什么？

which indicates the two aren't equivalent in terms of how they're being handled. What am I doing wrong here?

推荐答案

如 Grails手册5.2.4 ，这是使集合成为 List 的正确方法。

As described in section 5.2.4 of the Grails manual, this is the correct way to make the collection a List.

我怀疑问题在于，默认情况下，约束 nullable（false）应用于所有的域类属性，你正试图为这个属性保存一个空值。为了解决这个问题，添加一个约束条件，允许该属性为null（如果这就是你想要的）

I suspect the problem is that by default the constraint nullable(false) is applied to all domain class properties and you're trying to save a null value for this property. To fix this, add a constraint that allows this property to be null (if that's what you want

List myList
static constraints = {
    myList(nullable: true)
}

在验证/保存对象之前确保该属性不为空。

Alternatively, make sure that the property is not null before the object is validated/saved.

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