我在使用Select输入的表单时遇到问题。此输入用于选择列表中的用户。列表应仅包含当前使用的组中的用户。
我找到了一个解决方案，但是我不完全确定我在表单定义中做了什么（我不完全理解def __init__部分是如何工作的）。当然，我的代码不起作用：我获得了正确的表单，并提供了所需的选项，但如果提交数据，则不会保存在数据库中。
我已经能够检查表格是否有效（它不是），错误如下：
类别-选择有效选项。该选项不是可用选项之一。
（我在用户字段中也有同样的错误）。我找不到我的方式在这一点上，所以如果你能帮助，将不胜感激！
我的模特：

class Group(models.Model):
    name = models.CharField(max_length=100)
    def __str__(self):
        return self.name   
    
class User(AbstractUser):
    groups = models.ManyToManyField(Group)
    current_group = models.ForeignKey(Group, on_delete=models.SET_NULL,blank = True , null = True, related_name="current_group")

class Category(models.Model):
    name = models.CharField(max_length=100)
    groups = models.ManyToManyField(Group)

    def __str__(self):
        return self.name

class Expanses(models.Model):
    date = models.DateTimeField()
    amount = models.DecimalField(decimal_places=2, max_digits=12)
    category = models.ForeignKey(Category, on_delete=models.CASCADE)
    user = models.ForeignKey(settings.AUTH_USER_MODEL, on_delete=models.CASCADE)
    group = models.ForeignKey(Group, on_delete=models.CASCADE)
    comment = models.CharField(max_length=500)
    
    def __str__(self):
        return self.amount

我的表格：

class CreateExpanseForm(forms.ModelForm):
    class Meta:
        model = Expanses
        fields = ['date', 'amount', 'category', 'user','comment']
        widgets={'date':DateInput(attrs={'placeholder':'Date', 'class':'form-input', 'type':'date'}),
                 'amount':TextInput(attrs={'placeholder':'Amount', 'class':'form-input', 'type':'text'}),
                 'category':Select(attrs={'placeholder':'Category', 'class':'form-select', 'type':'text'}),
                 'user':Select(attrs={'placeholder':'user', 'class':'form-select', 'type':'text'}),
                 'comment':TextInput(attrs={'placeholder':'comment', 'class':'form-input', 'type':'text'}),}
    
    def __init__(self, *args, **kwargs):
        user_choices = kwargs.pop('user_choices', None)
        category_choices = kwargs.pop('category_choices', None)
        
        super().__init__(*args, **kwargs)
        if user_choices:
            self.fields['user'].choices = user_choices
        if category_choices:
            self.fields['category'].choices = category_choices

我的看法：

def SummaryView(request):
    createExpanseForm = CreateExpanseForm(user_choices = [(user.username, user.username) for user in request.user.current_group.user_set.all()],
                                          category_choices = [(category.name, category.name) for category in request.user.current_group.category_set.all()])
    if request.method == "POST":
        if 'createExpanse' in request.POST:
            createExpanseForm = CreateExpanseForm(user_choices = [(user.username, user.username) for user in request.user.current_group.user_set.all()],
                                                  category_choices = [(category.name, category.name) for category in request.user.current_group.category_set.all()],
                                                  data=request.POST)
            if createExpanseForm.is_valid():
                expanse = createExpanseForm.save()
                if expanse is not None:
                    expanse.group = request.user.current_group
                    expanse.save()
                else:
                    messages.success(request, "Error!")
            
    context = {'createExpanseForm':createExpanseForm}
    return render(request, 'app/summary.html', context)