grails - 域使用addTo Map导致错误

Question

我的团队只有4位玩家。每个玩家的位置都很重要，因此我认为我可以为自己的玩家使用 map ，这是个不错的方法，其键为:pos1，pos2，pos3，pos4

class Team {

Map players = [pos1:null, pos2:null, pos3:null, pos4:null]
static hasMany = [players:Player]

League league

static belongsTo = [club:Club]

static constraints = {
    league nullable:true
    players nullable:true

}
}

和我的播放器:

class Player{

static belongsTo = [club:Club, team:Team]

String firstname
String lastname

Team team



static constraints = {
    team nullable:true
    firstname nullable:true
    lastname nullable:true

}

public String fullname() {
    return firstname + " " + lastname + " - " + team?.id ?: "R"
}
}

我使用addToPlayers()方法自动更新播放器，但是尝试以下操作时出现错误:

def player = new Player(firstname:"Peter", lastname:"Pan")
def team = new Team()
team.addToPlayers([pos1:player])

Stacktrace在说:

Groovy.lang.MissingMethodException: No signature of method:
org.hibernate.collection.PersistentMap.add() is applicable for argument types:
(at.panda.Player) values: [at.panda.Player : null]
Possible solutions: any(), any(groovy.lang.Closure), any(groovy.lang.Closure), wait(),
wait(long), get(java.lang.Object)

at at.panda.PlayerController$_closure4.doCall(PlayerController.groovy:39)

at at.panda.PlayerController$_closure4.doCall(PlayerController.groovy)

at java.lang.Thread.run(Thread.java:662)

那花了我很多时间，我希望有人能帮助我。如果您有更好的解决方案，则无需坚持使用“ map ”。

Answer 1

就个人而言，我会像这样为您的域建模:

class Team {

  //Map players = [pos1:null, pos2:null, pos3:null, pos4:null]
  static hasMany = [players:Player]

  // The reference to league is now specified below in belongsTo       
  //League league

  static belongsTo = [club:Club,league:League]

  static constraints = {
    league nullable:true

    // must have 4 players
    players(size: 4..4)
  }
}

class Player{

  // Remove the reference to club as this can be retrieved through the Team
  static belongsTo = [/*club:Club,*/ team:Team]

  String firstname
  String lastname
  Integer position

  // Remove this duplicate reference to team
  //Team team        

  static constraints = {
    team nullable:true
    firstname nullable:true
    lastname nullable:true 

    // This should ensure that you can't create 2 players with the same position
    // in the same team
    position(unique:'team')   
  }
}

该模型将使按位置排列所有玩家的过程变得更加容易，如果您决定更改玩家数量，只需更改约束players(size: 4..4)
我会考虑向Team添加addPlayer(Player player)方法，以正确设置position属性。

如果尚未测试以上任何代码，请小心处理。