Question

I can’t see why in my application i am getting this error. As all primary keys are text fields are integers. Here is my code:

forms.py

 class EventAttendForm(forms.Form):
     talk = forms.ModelChoiceField(queryset=Talk.objects.all())
     membersAttended = forms.ModelMultipleChoiceField(queryset=Member.objects.all())

models.py

 class Talk(models.Model):
     title = models.CharField(max_length=200, primary_key=True)  
 class Member(models.Model):
     name = models.CharField(max_length=200)
     membership_number = models.CharField(max_length=200, primary_key=True)
     talks = models.ManyToManyField(Talk, through='Event_Attendance')
 class Event_Attendance(models.Model):
     talk = models.ForeignKey('Talk')
     membersAttended = models.ForeignKey('Member')

views.py

 def addAttendance(request):
     #eventAttendanceForm
     if request.method == 'POST':
          eventAttendForm = EventAttendForm(request.POST)
      for member in request.POST['membersAttended']:
            ea = Event_Attendance(request.POST['talk'], member)
            ea.save()
    return HttpResponseRedirect('../../../talks/')      
else:
    eventAttendForm = EventAttendForm()
    return render_to_response('attendance/addAttendance.html',{'eventAttendForm': eventAttendForm})

I cannot see why I am getting this error. The exact error is:

 Exception Type:    ValueError
 Exception Value:   invalid literal for int() with base 10: 'redirectTest'

RedirectTest is a Talk that I created with my form for the add talk to check that redirection was working correctly. The line of code that it is saying is causing the problem is ea.save().

Answer 1

Consider the line

ea = Event_Attendance(request.POST['talk'], member)

You are creating an instance of the model Event_Attendance. The constructor expects the first argument to be an instance of Talk. Instead you are supplying it with a string which is the title of the talk.

A quick fix would be to look up the Talk instance with the matching title and pass it as an argument to the constructor. Something like this:

talk = Talk.objects.get(title = request.POST['talk'])
ea = Event_Attendance(talk = talk, membersAttended = member)
ea.save()

This will work but is not the best way to go about it. For one, the first line can always raise a DoesNotExist if a Talk with the given title is not found. Second you are accessing the POST variables directly rather than using the Form to validate them.

A better answer would therefore be:

eventAttendForm = EventAttendForm(request.POST.copy())
if eventAttendForm.is_valid():
    talk = eventAttendForm.cleaned_data['talk']
    membersAttended = eventAttendForm.cleaned_data['membersAttended']

    for member in membersAttended:
        ea = Event_Attendance(talk = talk, membersAttended = member)
        ea.save()