Django迭代多对多对象

我的主要问题是,我的代码从未进入for循环,尽管在调试器中我可以看到硬件存在。for循环被跳过了,我不明白为什么会这样。

型号:

class Hardware(models.Model):
    name = models.CharField(max_length=30)
    description = models.TextField()

class Bundle(models.Model):
    name = models.CharField(max_length=30)
    description = models.TextField()
    devices = models.ManyToManyField(Hardware)

class BundleForm(ModelForm):

    class Meta:
        model = Bundle
        fields = ('name', 'description', 'devices')
        labels = {
            'name': _('Bundlename'),
            'description': _('Beschreibung des Bundle'),
            'devices': _('Hardware im Bundle')
            }

视图:

elif request.method == 'POST' and 'newbundle' in request.POST:
    form = BundleForm(request.POST)
    if form.is_valid():
        bundle = form.save(commit=False)
        bundle.save()

        for hardware in bundle.devices.all():
            print(hardware)

        messages.success(request, 'Erfolg! Die Daten wurden erfolgreich gespeichert.')
        return redirect('/knowledgeeditor/bundle/', {'messages': messages})