如何为+ =：'DeferredAttribute'和'int'修复TypeError不支持的操作数类型

Question

i am trying to create a fantasy-like app, i want the user's starting 11 to increase each time they add a player, and the team budget decrease by the amount of the player price.

i am using the django web framework for python.

here is my model for the user team

class UserTeam(models.Model):
    name = models.CharField(max_length=50)
    user = models.OneToOneField(User, on_delete=models.CASCADE, default=None)
    players = models.ManyToManyField(Player)
    budget = models.IntegerField(default=100000000)
    FORMATION_CHOICES = (
        ('4-3-3', '4-DEF 3-MID 3-ATT'),
        ('4-4-2', '4-DEF 4-MID 2-ATT'),
        ('3-4-3', '3-DEF 4-MID 3-ATT'),
        ('5-3-2', '5-DEF 3-MID 2-ATT'),
    )
    formation = models.CharField(max_length=10, choices = FORMATION_CHOICES)
    starting_xi = models.IntegerField(default=0)
    bench_sub = models.IntegerField(default=0)
    total_score = models.IntegerField(default=0)
    round_score = models.IntegerField(default=0)
    Highest_team_score = models.IntegerField(default=0)


    @classmethod
    def transfer_player_in(cls, user, new_player):
        team, created = cls.objects.get_or_create(
            user=user
        )

        team.players.add(new_player)

    @classmethod
    def transfer_player_out(cls, user, new_player):
        team, created = cls.objects.get_or_create(
            user=user
        )

        team.players.remove(new_player)

my player model

class Player(models.Model):
    POSITION_CHOICES = (
        ('ATT', 'Attacker'),
        ('MID', 'Midfielder'),
        ('DEF', 'Defender'),
        ('GK', 'GoalKeeper'),
    )
    name = models.CharField(max_length=50)
    FirstName = models.CharField(max_length=20)
    LastName = models.CharField(max_length=20)
    position = models.CharField(max_length=3, choices = POSITION_CHOICES)
    country = models.ManyToManyField(Country)
    photo = models.ImageField(blank=True)
    price = models.IntegerField(default=0)
    total_score = models.IntegerField(default=0)

here is the view function to handle transfer of players in and out

def Transfer_Player(request, operation, pk):
    player= Player.objects.get(pk=pk)  #gets a particular player into the variable player
    if operation =='add':    #if user wants to buy player
        UserTeam.starting_xi += 1
        UserTeam.budget = UserTeam.budget - Player.price
        UserTeam.transfer_player_in(request.user, player)  #add player to team
        UserTeam.save

    elif operation =='sell':
        UserTeam.transfer_player_out(request.user, player)
    else:
        pass
    return redirect('/Fantasy')

i expect the user's starting 11 to increase by 1 each time they perform the add operation and the user budget to be decreased by the price of the player, but instead am getting a TypeError, unsupported operand type(s) for +=: 'DeferredAttribute' and 'int'.

Answer 1

You need to have a concrete instance of a UserTeam in order to do what you want. I suspect that your code should look like this:

if operation =='add':    #if user wants to buy player
    team = UerTeam.objects.get(user_id=request.user.id)
    team.starting_xi += 1
    team.budget -= player.price
    team.save()
    UserTeam.transfer_player_in(request.user, player)  #add player to team