Grails - How to return a collection from a belogsTo relationship with a filter

I have a 'User' and a 'UserOrder' class in grails. There is a 'belongsTo' relationship defined on the userOrder class and a hasMany relationship on the 'User' class, like so:

class User {

    String username
    String password

    static hasMany = [orders:UserOrder]

    Set<UserOrder> getUserOrder() {
        return orders.findWhere(status: 0)
    }
}

class UserOrder {
    User user
    Integer status

    static belongsTo = [User]
}

My issue is that the 'getUserOrder' method doesn't work. I just want it to return the first (any) UserOrder with the status set to '0', but when I run the above code, I get the following error:

No signature of method: org.hibernate.collection.PersistentSet.findWhere() is applicable for argument types: (开发者_如何学Cjava.util.LinkedHashMap) values: [[status:0]]

How do I get the method to just return a UserOrder, belonging to this User with a status of '0'?

You can't do effective filtering on collection property - all the collection will be fetched first. Plus, findWhere() is a static method. For effective DB querying, just use

UserOrder getUserOrder() {
    return UserOrder.findWhere(user: this, status: 0)
}

Note the return type change. To get a Set of matching orders, use

UserOrder.findAllWhere(user: this, status: 0)