hibernate - Grails hasMany association check

Question

What is the cheapest way (from performance stand point) to figure out if hasMany association has any members? I am trying to avoid retrieval of all children. Is there a clean way to count children using gorm?

The use case here is to show(or not) a [+] on the UI of a parent object.

Answer 1

不可能，我想用一个直接的 gorm 表达

Answer 2

我认为通过对孩子进行 size() 检查不会丢失任何东西（尤其是在使用缓存的情况下）。另一种选择是去规范化一点并将计数保留为父级的列。我们为跟踪订单标题的订单项目数量的 ecomm 站点执行此操作。

您还可以查看 countBy 动态查找器。