No owner defined between domain classes: many to many relationship - grails

Question

These are my domain classes:
class Game {
static hasMany = [players: User]
static belongsTo = [owner: User]
}
class User {
static hasMany = [games: Game]
}
If I try to use them as they are I get No owner defined between domain classes. So I need to set the owner of the relationship. Adding static belongsTo = Game to User causes Domain classes cannot own each other in a many-to-many relationship.
The only other option I can think of is to add static belongsTo = User to the Game class but I already have a belongsTo there.
How do I model this?

Answer 1

class Game {
User owner
static hasMany = [players: User]
static belongsTo = User
}
class User {
static hasMany = [games: Game]
}
You will have to specify one side of the relationship, as the owner, by doing this you will make User domain class as the owner of the many to many relationship.
The belongsTo field controls where the dynamic addTo*() methods can be used
from. we’re able to call User.addToGames() because Game belongsTo
User. we can’t call Game.addToPlayers().

Answer 2

Try this:
class Game {
User owner
static hasMany = [players: User]
static belongsTo = User
}

Answer 3

maybe it would be better not to use "belongsTo" at all? I mean using simple field reference like
class Game {
User owner
static hasMany = [players: User]
}
FYI,
I would be careful with using "owner" field name, it might cause problems when used somehow in a closure which has its own "owner" reference (e.g. in criteria builder)
I know it caused problems back in grails 1.3.X, I don't know if it's still the case

Answer 4

try this:
class Game {
User owner
static hasMany = [players: User]
static belongsTo = User
}
class User {
static hasMany = [games: Game, owns: Game]
static mappedBy = [games:'players', owns: 'owner']
}
this settings work for me. And here is a good thread for mappedBy: GORM mappedBy and mapping difference