Graphql null 指针异常即使不是 null

Question

I am trying to create a player using createPlayer mutation. I enter the parameters for playerDTO but I get a null pointer exception

Cannot invoke "com.example.basketballteam.dto.PlayerDTO.getName()" because "playerdto" is null

Here is my mutation:

input PlayerDTO{
    name:String!,
    lastName:String!,
    position:Position!
}
type Mutation{
    createPlayer(plyr: PlayerDTO):Player
    deletePlayer(id: ID):Boolean
    addPlayerToTeam(id:ID,tid:ID):Player
}

here is my controller

  @MutationMapping
    public Player createPlayer(@Argument PlayerDTO playerdto){
        return playerRepository.save(playerMapper.ToEntity(playerdto));
    }

and this is my mapper:

  public Player ToEntity(PlayerDTO playerdto){
        Player player = new Player();
        player.setName(playerdto.getName());
        player.setLastName(playerdto.getLastName());
        player.setPosition(playerdto.getPosition());

        return player;
    }

Answer 1

The name in the graphql schema (type Mutation) must be the same as your data transfer object parameter in your controller

input PlayerDTO{
    name:String!,
    lastName:String!,
    position:Position!
}

type Mutation{
    createPlayer(player: PlayerDTO):Player
    deletePlayer(id: ID):Boolean
    addPlayerToTeam(id:ID,tid:ID):Player
}

With this controller it should work

  @MutationMapping
  public Player createPlayer(@Argument PlayerDTO player){
    return playerRepository.save(playerMapper.ToEntity(player));
  }