django模型形式，根据ForeignKey模型中的值限制选择

Question

我有两个模型:League 和 Team。 Team 有一个指向 League 的外键链接。我希望能够根据 League 中存储的值设置可供 Team 使用的选项。具体来说:

class League(models.Model):
    number_of_teams = models.IntegerField()

class Team(models.Model):
    league = models.ForeignKey(League)
    draft_slot = models.IntegerField(choices=[(i+1,i+1) for i in range(?????????)])

我认识到我无法在 Team 模型中准确定义我的 draft_slot.choices。所以我希望像这样建立团队:

class Team(models.Model):
    league = models.ForeignKey(League)
    draft_slot = models.IntegerField()

我已经建立了Team的ModelForm:

class TeamModelForm(ModelForm):
    class Meta:
        model = Team

以及团队 ModelForm的 View :

def SetupTeam(request, fanatic_slug=None, league_slug=None):
    league = League.objects.get(slug=league_slug)
    form = TeamModelForm()
    return render_to_response('league/addteam.html', {
        'form': form
    }, context_instance = RequestContext(request))

我需要什么 foo 才能使用 league.id、league.number_of_teams 以便 TeamModelForm 的 View 预填充 team .league 并渲染一个字段来表示 team.draft_slot ，看起来像

draft_slot = models.IntegerField(choices=[(i+1,i+1) for i in range(league.number_of_teams+1)])

Answer 1

工作答案:

class TeamModelForm(ModelForm):
    def __init__(self, *args, **kwargs):
        super(TeamModelForm, self).__init__(*args, **kwargs)
        if self.instance:
            n = self.instance.number_of_teams
            self.fields['draft_position'].widget.choices = [(i+1,i+1) for i in range(n)]

    class Meta:
        model = Team
        widgets = {'draft_position': Select(choices=())}