Updating a Record Creates a new Record

#django

I wish to update a record in Django using a form, but instead it creates a new record. I know it has to do with using get(), but I don't know how to fix it. Here is the relevant code:

my form:

class  AddRecordForm(forms.ModelForm):

    class Meta:
        model = Model2
        fields = ('field1', 'field2')

my Models:

class Model2(models.Model):

    id = models.CharField(primary_key=True, max_length=12)
    created_at = models.DateTimeField(auto_now_add=True)
    field3 = models.ForeignKey(Model3,  on_delete=models.PROTECT, related_name='master')
    field4 = models.PositiveSmallIntegerField()

    class Meta:
        ordering = ['id']

    def __str__(self):
        return(f"{self.field3} ")

class Model1(models.Model):

    field1 = models.ForeignKey(Model2,  on_delete=models.PROTECT, related_name='list')
    created_at = models.DateTimeField(auto_now_add=True)
    field2 =  models.PositiveSmallIntegerField(null=True, blank=True)

and my view:

def update_record(request, pk):


    record = Model2.objects.get(field2=pk)
    form = AddRecordForm(instance=record)
    if request.method == 'POST':
            form = AddRecordForm(request.POST, instance=record)
        if form.is_valid():
            form.save()
            messages.success(request, "Record updated successfully!")
        return render(request, 'home', {})
        context = {'form':form}
    return render(request, 'update_record.html', context)

Any help would be very much appreciated. Thanks.