grails - 跟踪用户和游戏的域类

Question

我正在尝试做一些看起来很简单的事情。我有一个用户类，我有一个匹配两个用户的游戏类。就是这么简单：

class User {
    String username
    static hasMany = [games:Game]
}

class Game {
    User player1
    User player2
}

当我运行这个时，我得到了

Caused by GrailsDomainException: Property [games] in class [class User] is a bidirectional one-to-many with two possible properties on the inverse side. Either name one of the properties on other side of the relationship [user] or use the 'mappedBy' static to define the property that the relationship is mapped with. Example: static mappedBy = [games:'myprop']

所以我做了一些挖掘并找到了mappedBy并将我的代码更改为：

class User {
    String username
    static hasMany = [games:Game]
    static mappedBy = [games:'gid']
}

class Game {
    User player1
    User player2
    static mapping = {
        id generator:'identity', name:'gid'
    }
}

现在我明白了

Non-existent mapping property [gid] specified for property [games] in class [class User]

我究竟做错了什么？

Answer 1

所以这可能是你想要的：

class User {

    static mappedBy = [player1Games: 'player1', player2Games: 'player2']

    static hasMany = [player1Games: Game, player2Games: Game]

    static belongsTo = Game
}

class Game {
    User player1
    User player2
}

编辑新规则：

class User {
    static hasMany = [ games: Game ]
    static belongsTo = Game
}

class Game {
    static hasMany = [ players: User ]
    static constraints = {
        players(maxSize: 2)
    }
}