django - How to access the previous row from the database -

django - How to access the previous row from the database -

views.py

apptruepower = form.cleaned_data['truepower_reading'] appapparent = form.cleaned_data['apparentpower_reading'] appvoltage = form.cleaned_data['voltage_reading'] appdate = form.cleaned_data['date'] apptime = form.cleaned_data['time'] prevdate=kebreading.objects.latest("id") print prevdate.truepower_reading print id kebreading.objects.filter(id=id).update(truepower_reading=apptruepower,apparentpower_reading=appapparent, voltage_reading=appvoltage,datetime_reading=datetime.combine(appdate,apptime)) a=kebreading.objects.filter(id=id).values("truepower_reading") print b=kebreading.objects.filter(id=id).values("apparentpower_reading") print b print prevdate.truepower_reading

when editing row in django forms. need access previous row calculation. sumbody suggest me how can previous row. if utilize model.s.object.latest() lastly row entered,but in case need previous row i.e previuos row of current row im going edit.

i depends upon order mean rows. if want previous row id can do

curr_row = kebreading.objects.filter(id=current_id) #decrement id until find valid record, previous id might have deleted. prev_row = kebreading.objects.filter(id=current_id-1)

if want order other field then

rows = kebreading.objects.order_by('-some_field_to_order') # utilize - reverse ordering current_row = rows[0] prev_row = rows[1] #verify index errors though.

django