How to begin debugging POST and GET requests in Django and Python Shell - html

Question

I have written the following code.
The issue that I am having is that the database is not being updated and a new record is not being made. I am assuming that the way I am retrieving my POST are incorrect but that's why I am asking where do I begin to debug? I have created template variables for quantity,action,building, and test. When I try to call them in the html {{ test }} for example nothing ever shows up even the one that is hardcoded. I used firebug and the form is indeed posting the values that should be posted.
the form consists of two drop down menus one for action and one for building. A numerical input quantity, a text box and a submit button. If anyone can offer me some advice it would be appreciated. I really don't understand why the hardcoded one doesn't show up
If you need any more information please let me know.
def update(request,Type_slug, slug, id):
error = False
Slug = slug
ID = id
Type = Type_slug
test = 'test'
quantity = request.POST['Qty']
action = request.POST['Action']
building = request.POST['Building']
comments = request.POST['Comments']
if Type == 'Chemicals':
item = Chemicals.objects.filter(S_field=Slug, id= ID)
New_Record = ChemicalRecord(Name=item.Name,Barcode=item.Barcode,Cost=item.Cost,Action=action,Building=building)
if building == 'Marcus':
building_two = 'Pettit'
elif building =='Pettit':
building_two ='Marcus'
Record_one = ChemicalRecord.objects.filter(Barcode=New_Record.Barcode).filter(Building=New_Record.Building)
if Record_one:
Record_one = ChemicalRecord.objects.filter(Barcode=New_Record.Barcode).filter(Building=New_Record.Building).latest('id')
New_Record.On_hand = Record_one.On_hand
else:
New_Record.On_hand = 0
if action == 'Receiving':
New_Record.On_hand = New_Record.On_hand+quantity
elif action == 'Removing':
New_Record.On_hand = New_Record.On_hand-quantity
Record_two = ChemicalRecord.objects.filter(Barcode=New_Record.Barcode).filter(Building=building_two)
if Record_two:
Record_two = ChemicalRecord.objects.filter(Barcode=New_Record.Barcode).filter(Building=building_two).latest('id')
Record_two_qty = Record_two.On_hand
else:
Record_two_qty = 0
New_qty = New_Record.On_hand+Record_two_qty
Chemicals.objects.filter(Barcode=obj.Barcode).update(On_hand=New_qty)
New_Record.save()

Answer 1

You can use import pdb;pdb.set_trace() for debugging.