Select of hasMany mapping with GORM in Grails

Question

Suppose I have a setup like the following:

class User {
    static hasMany = [items : Item];
}

class Item {
    String name;
}

I'm trying to select all Users that have an Item in that hasMany mapping. I have an id of an Item, and want to find all users that “have” that item.

Is there a HQL query I can run that will do this or better yet, a built in GORM function that handles this query?

Supposing this were straight SQL I would do something like:

SELECT `user_id` FROM `user_item` WHERE `item_id`=[ID]

Looking in H2 I can write the query

SELECT USER_ID FROM USER_ITEM WHERE ITEM_ID=1;

I can expand this SQL to include the entire user object:

SELECT * FROM user, user_item WHERE user_item.item_id=[item id] AND user.id = user_user.user_items_id;

Answer 1

This HQL will work:

Item item = ...
Item.executeQuery(
   'from User u where :item in elements(u.items)',
   [item: item])