执行保存后数据库会自己增加一条心的记录是咋回事呢？ ``` python @login_required def con_save(request): con = Contract.objects.get(pk=request.POST['conid']) con.orderno = request.POST['orderno'] con.contractno = request.POST['contractno'] con.factory = request.POST['factory'] con.factory_addr = request.POST['factory_addr'] con.factory_attn = request.POST['factory_attn'] con.goodsname = request.POST['goodsname'] con.qty = request.POST['qty'] con.pol = request.POST['pol'] con.pod = request.POST['pod'] con.op = request.POST['op'] con.pkg = request.POST['pkg'] con.cntr_type = request.POST['cntr_type'] con.save(update_fields=['orderno']) return HttpResponseRedirect(reverse('jask:con_detail', args=(con.id,))) ```