How to get all fields of related object Django-CodePudding

I have two models:

class Checklist(models.Model):
    author = models.ForeignKey(User, null=True, on_delete=models.SET_NULL)
    client_name = models.ForeignKey(Client, on_delete=models.CASCADE,
                                     related_name='details')
    fieldA = models.CharField(max_length=25, blank=True, null=True)
    fieldA_Check= models.BooleanField(default=False)
    fieldB = models.CharField(max_length=25, blank=True, null=True)
    fieldB_Check= models.BooleanField(default=False)


class Client(models.Model):
    client_fieldA = models.CharField(max_length=25)
    client_fieldB = models.CharField(max_length=25)
    client_fieldC = models.CharField(max_length=25)

Now I trying to change Client instance fields values via Checklist using following code:

@login_required
def create_order(request, pk):
    instance = get_object_or_404(CheckList, id=pk)
    form = myForm(request.POST or None, instance=instance)
    if form.is_valid():
        form.save()
        messages.success(request, 'Test message')
        return get_PDF_order(request, pk)
    return render(request, 'templates/create_order.html', {'form': form})

here is my form:

class myForm(forms.ModelForm):
    class Meta:
        model = Client
        fields = ('client_fieldA', 'client_fieldB', 'client_fieldC')

        widgets = {
            'client_fieldA': forms.TextInput(attrs={'class': 'form-control'}),
            'client_fieldB': forms.TextInput(attrs={'class': 'form-control'}),
            'client_fieldC': forms.TextInput(attrs={'class': 'form-control'}),
        }

And it's works but only once. Data saved and I get a pdf file with this data, but subsequent attempts do not change anything. The field value still the same. I'm guessing that it is because I working with the Checklist instance but not Client. So, my questions are: 1) How I can get an access to all Client fields (a queryset of all Client fileds) via Checklist? 2) Although my code is incorrect - why does it work (once)? I mean why does it save first time?

Thank you all in advance!

CodePudding user response：

To formalize the answer, the instance is actually an instance of the model the form is based on. Thus, in your case, you cannot pass a CheckList instance to a form based on Client
Anyway, as far as you have the CheckList id, you can easily obtain the Client, and the code for your view will be:

@login_required
def create_order(request, pk):
    instance = get_object_or_404(CheckList, id=pk)
    form = myForm(request.POST or None, instance=instance.client_name)
    if form.is_valid():
        form.save()
        messages.success(request, 'Test message')
        return get_PDF_order(request, pk)
    return render(request, 'templates/create_order.html', {'form': form})

CodePudding user response：

You pass it always the same instance, so what happens is that you are probably overwriting the same record over and over. I would recommend you to split this using the django-provided generic class-based views CreateView and UpdateView.

Stop reinventing the wheel, use class-based views. It'll pay off big time in the long term.