Groils在Grails列表上-不起作用？

Question

Removing an element from a list isn't working, which doesn't make any sense. Am I missing some special semantics peculiar to dealing with a Grails domain object list?

In controller:

def userCreate = {
    def workgroupInstance = new Workgroup()
    workgroupInstance.manager = authUserDomain
    flash.message = User.list().toString()
    def usersWithoutThisOne = User.list() - authUserDomain
    flash.message = flash.message + "removed ${authUserDomain}, new list is ${usersWithoutThisOne}"
    return ['workgroupInstance':workgroupInstance, 'users':usersWithoutThisOne]
}

Results in this being displayed in flash.message

[boogie, toogie, choogie, cookie]removed boogie, new list is [boogie, toogie, choogie, cookie]

Answer 1

Where does authUserDomain come from?

If you haven't implemented a customn .equals() on User (based on username or someother unique identified) then it may not be the same object that is returned via User.list(). An element will only be removed if it matches an existing object using .equals()

Answer 2

如果您打算将用户从工作组中永久删除，则需要使用grails removeFrom函数来摆脱存储在具有多个关联的类中。

Answer 3

I am not sure about this one. Don't have a Groovy interpreter available right now. But IIRC and as this article suggests, the - on lists expects to operate on two lists, ie,

list - other

is actually more like

list.removeAll(other)

(in Java terms), not the intended

list.remove(other)

You might try

modifiedList = originalList - [elementToRemove]