More validation to the free-form price text box and allow for decimal places

common/djangoapps/course_modes/views.py

+import decimal
 from django.core.urlresolvers import reverse
 from django.http import (
     HttpResponse, HttpResponseBadRequest, HttpResponseForbidden, Http404
@@ -63,15 +64,22 @@ class ChooseModeView(View):
             amount = request.POST.get("contribution") or \
                 request.POST.get("contribution-other-amt") or 0
 
-            donation_for_course = request.session.get("donation_for_course", {})
-            donation_for_course[course_id] = amount
-            request.session["donation_for_course"] = donation_for_course
+            try:
+                # validate the amount passed in and force it into two digits
+                amount_value = decimal.Decimal(amount).quantize(decimal.Decimal('.01'), rounding=decimal.ROUND_DOWN)
+            except decimal.InvalidOperation:
+                error_msg = _("Invalid amount selected.")
+                return self.get(request, error=error_msg)
 
             # Check for minimum pricing
-            if int(amount) < mode_info.min_price:
+            if amount_value < mode_info.min_price:
                 error_msg = _("No selected price or selected price is too low.")
                 return self.get(request, error=error_msg)
 
+            donation_for_course = request.session.get("donation_for_course", {})
+            donation_for_course[course_id] = donation_for_course
+            request.session["donation_for_course"] = donation_for_course
+
             return redirect(
                 "{}?{}".format(
                     reverse('verify_student_show_requirements'),

lms/djangoapps/verify_student/views.py

@@ -4,6 +4,7 @@
 """
 import json
 import logging
+import decimal
 
 from mitxmako.shortcuts import render_to_response
 
@@ -68,19 +69,23 @@ def create_order(request):
 
     course_id = request.POST['course_id']
     contribution = request.POST.get("contribution", 0)
+    try:
+        amount = decimal.Decimal(contribution).quantize(decimal.Decimal('.01'), rounding=decimal.ROUND_DOWN)
+    except decimal.InvalidOperation:
+        return HttpResponseBadRequest(_("Selected price is not valid number."))
 
     verified_mode = CourseMode.modes_for_course_dict(course_id).get('verified', None)
     # make sure this course has a verified mode
     if not verified_mode:
         return HttpResponseBadRequest(_("This course doesn't support verified certificates"))
 
-    if int(contribution) < verified_mode.min_price:
+    if amount < verified_mode.min_price:
         return HttpResponseBadRequest(_("No selected price or selected price is below minimum."))
 
     # I know, we should check this is valid. All kinds of stuff missing here
     cart = Order.get_cart_for_user(request.user)
     cart.clear()
-    CertificateItem.add_to_order(cart, course_id, contribution, 'verified')
+    CertificateItem.add_to_order(cart, course_id, amount, 'verified')
 
     params = get_signed_purchase_params(cart)