Django 表格与 m2m 关系不保存

Question

I have a form where I want request.user to populate as little as possible and rely on the views to populate other fields automatically.

As a result, some of these fields are not rendered on the form.

The code in my view seems to work fine for the FK relationship , but some reason the m2m is failing.

It's probably the first time I am trying to save a form with m2m and I am probably missing something.

At the moment the error I get with the current code is 'VoucherForm' object has no attribute 'user' .

If I remove voucherform.user.add(userprofile) from the views the form will save, but will not add the user.

model

class UserProfile(models.Model):
    user = models.OneToOneField(User, null=True, on_delete=models.CASCADE)

class Voucher(models.Model):
    user = models.ManyToManyField(User, blank=True)
    venue = models.ForeignKey(Venue, blank=True, null=True, related_name="vouchervenues", on_delete=models.CASCADE)
    title = models.TextField('voucher title', blank=True)
    terms = models.TextField('terms & conditions', blank=True)

form

class VoucherForm(ModelForm):
    class Meta:
        model = Voucher
        fields = ('title','terms')
        labels ={

            'title': '',
            'terms': '',

        }
        widgets = {

                    'title': forms.TextInput(attrs={'class':'form-control', 'placeholder':'Enter title'}),
                    'terms': forms.TextInput(attrs={'class':'form-control', 'placeholder':'Enter terms'}),
                   
                }

views

def add_voucher(request, userprofile_id):
    url = request.META.get('HTTP_REFERER')
    venue = UserProfile.objects.filter(user=request.user).values('venue')
    userprofile = UserProfile.objects.get(id=userprofile_id)
    
    submitted = False
    if request.method =="POST":
        voucherform = VoucherForm(request.POST)
        if voucherform.is_valid():
            data = voucherform.save(commit=False)
            data.user_id = userprofile.id
            data.venue_id = venue
            data.save()
            voucherform.save_m2m()
            voucherform.user.add(userprofile)
            return HttpResponseRedirect(url)
    else:
        voucherform = VoucherForm
        if 'submitted' in request.GET:
            submitted=True
    return redirect('venue-loyalty-card',{'submitted':submitted,'userprofile':userprofile})

Answer 1

Basically, the problem is that you haven't mentioned user field in VoucherForm at fields so it says 'VoucherForm' object has no attribute 'user' , you can do the following:

from django.shortcuts import get_object_or_404

def add_voucher(request, userprofile_id):
    url = request.META.get('HTTP_REFERER')
    venue = UserProfile.objects.filter(user=request.user).values('venue')
    userprofile = UserProfile.objects.get(id=userprofile_id)
    
    submitted = False
    if request.method =="POST":
        voucherform = VoucherForm(request.POST)
        if voucherform.is_valid():
            data = voucherform.save(commit=False)
            data.user_id = userprofile.id
            data.venue_id = venue
            data.save()
            voucherform.save_m2m()
            current_voucher_instance= get_object_or_404(Voucher,id=data.id)
            current_voucher_instance.user.add(userprofile.id)
            return HttpResponseRedirect(url)
    else:
        voucherform = VoucherForm
        if 'submitted' in request.GET:
            submitted=True
    return redirect('venue-loyalty-card',{'submitted':submitted,'userprofile':userprofile})

Note: It is better to use get_object_or_404() thanget() as it calls get() on a given model manager, but it raises Http404 instead of the model's DoesNotExist exception.