python - '>' not supported between instances of ' int' 和 'NoneType' 。表单.is_valid

Question

尝试创建或更新类别模型时出现错误。当我尝试使用调试器保存或编辑时，不会出现此错误并且模型已保存。

View .py

def create(request):
    model = Category()
    if request.method == 'POST':
        form = CategoryForm(request.POST, instance=model)
        if form.is_valid():
            form.save()
            return HttpResponseRedirect('/cabinet/category/')
    else:
        form = CategoryForm(instance=model)
    return render(request, 'cabinet/category/create.html', {'form': form})

表单.py

class CategoryForm(forms.ModelForm):
    name = forms.CharField(widget=TextInputCustom())

    class Meta:
        model = Category
        fields = ['name']

模型.py

class Category(models.Model):
    name = models.CharField(unique=True)

    def __str__(self):
        return self.name

Answer 1

哦，我找到错误原因了。只需将 max_length=255 添加到 models.py 中的 models.CharField(unique=True)