Question

I’m pretty new with Django and the whole web-developing concept. I’ve only taken Java and C++ , but I got a job working as a web-developer at my university. I’m currently trying to implement a form – (http://albedo.csrcdev.com/pages/submit). In my models, I have one more field that doesn’t show up on my form, which is called Albedo. Albedo is supposed to be calculated by sum( outgoing1, outgoing2, outgoing3 ) / sum( incoming1, incoming2, incoming3 ). So my question is, how and where do I take those variables from the database, and assign the new calculated value to Albedo.

My co-worker told me to use ModelForm for my form, and try doing it in views.py but now I’m sitting here stuck and clueless and he just left for vacation! 🙁

Thanks in advance,

David

views.py

@login_requried
def submit( request ):
if request.method =='POST':
     form = DataEntryForm( request.POST )
     model = DataEntry( )
     if form.is_valid():
        form.save()
        return HttpResponseRedirect('/map/rebuild/')                                            


else:                                                                                           
    form = DataEntryForm( )                                                                        

return render_to_response(
      'pages/submit.html', { 'form': form },
      context_instance=RequestContext(request) )

Answer 1

form = DataEntryForm(request.POST)
if form.is_valid():
    instance = form.save(commit=False)
    instance.albedo = do_calc(instance.whatever0, instance.whatever1)
    instance.save()
    return HttpResponseRedirect('/map/rebuild/')

Note that you don’t need to instantiate model = DataEntry() manually – if DataEntryForm is a ModelForm subclass, it’ll create the model when you call .save().

It would probably be a good idea to encapsulate the calculation in a DataEntry.update_albedo() method or something. You would call that before instance.save() instead doing the calculation in the view itself.