Django get current id to compare two tables in queryset filter

I'm struggling to achieve a simple queryset filter because i can't find how to get the current id of my form.

view.py

def update_record(request, pk):
    if request.user.is_authenticated:
        current_record = Record.objects.get(id=pk)
        form = AddRecordForm(request.POST or None, instance=current_record)
        if form.is_valid():
            form.save()
            messages.success(request, "Record Has Been Updated!")
            return redirect('home')
        return render(request, 'update_record.html', {'form':form})
    else:
        messages.success(request, "You Must Be Logged In...")
        return redirect('home')

forms.py

class AddRecordForm(forms.ModelForm):
    testrever = forms.ModelMultipleChoiceField(widget=forms.widgets.SelectMultiple, queryset=BDC.objects.filter(ref = ???current.id.of.Record.model???).values_list('model'))

    class Meta:
        model = Record
        exclude = ("user",)



class BDCform(forms.ModelForm):
    ref = forms.CharField(required=False, widget=forms.widgets.TextInput(attrs={"placeholder":"First Name", "class":"form-control"}), label="")
    model = forms.CharField(required=False, widget=forms.widgets.TextInput(attrs={"placeholder":"Last Name", "class":"form-control"}), label="")

    class Meta:
        model = BDC
        exclude = ("user",)

models.py

    class Record(models.Model):
        id = models.CharField(primary_key=True, max_length=50)
        testrever = models.JSONField(max_length=500) 
    
        def __str__(self):
            return (f"{self.first_name} {self.last_name}")

    class BDC(models.Model):
        ref = models.CharField(max_length=50)
        model = models.CharField(max_length=50)

My problem is in this line in forms.py:

queryset=BDC.objects.filter(ref = ???current.id.of.Record.model??? ).values_list('model')

How can i get the current ID of the Record form to compare it with "ref" of BDC form so i can populate the widget with the results ?

Thanks

You can't put a queryset involving non-constant values in a class definition. classes get defined when the module is imported.

(Well, slight lie. You could define the class as an inner class inside the view, rather than with module scope. In fact I'm not even sure why it's a bad idea, apart from I've never seen it or tried it. There's forms.modelform_factory, after all).

Your best bet would be to pass the queryset when you instantiate the form. Subclass the form's __init__:

def __init__(self, *args, **kwargs):
    bdcqs = kwargs.pop('bdc_qs', None)         # get the passed queryset
    super().__init__(*args, **kwargs) 
    self.fields['testrever'].queryset = bdcqs  # apply it to the field

and in the view,

def update_record(request, pk):
    if request.user.is_authenticated:
        current_record = Record.objects.get(id=pk)
        form = AddRecordForm(request.POST or None, 
            instance=current_record,
            bdc_qs = BDC.objects.filter(
                ref = pk   # if I understand the question right
            ).values_list('model')
        )
        ...

this what i did to fix the probleme :

def __init__(self, *args, **kwargs):
    self.storage_pk = kwargs.pop('pk')
    super(AddRecordForm, self).__init__(*args, **kwargs)
    self.fields['testrever'].queryset = BDC.objects.filter(ref=self.storage_pk).values_list('model', flat=True)

and modified

testrever = forms.ModelMultipleChoiceField(widget=forms.widgets.SelectMultiple, queryset=None)