本文介绍了Grails 域类:多列的唯一约束的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
假设一个简单的 Grails 域类:
Suppose a simple Grails domain class:
class Account {
String countryId;
String userName;
String password;
static constraints = {
...???...
}
}
要求用户名对于特定的 countryId 是唯一的,因此必须对两列有 unique 约束.如何在 constraints 定义中表达这一点?
It is required that user names are unique for a particular countryId, thus there must be a unique contraint on two columns. How to express this in the constraints definition?
推荐答案
userName(unique: ['countryId'])
您可以在数组中包含尽可能多的其他属性,这些属性构成了用户名的唯一"约束中必须考虑的其他属性.
You can include as many other properties in the array that make up the other properties that must be considered in the "unique" constraint on the username.
因此,例如,如果您想让 userName
在 countryId
和 provinceId
中唯一,它看起来像这样:
So, for example if you wanted to make userName
unique within a countryId
and provinceId
it would look like this:
userName(unique: ['countryId', 'provinceId']
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