Merge pull request #700 from MITx/kimth/H1P1-debug

Reset CapaProblem when state HTML is corrupt

common/lib/xmodule/xmodule/capa_module.py

+import cgi
 import datetime
 import dateutil
 import dateutil.parser
@@ -131,17 +132,17 @@ class CapaModule(XModule):
             self.weight = None
 
         if self.rerandomize == 'never':
-            seed = 1
+            self.seed = 1
         elif self.rerandomize == "per_student" and hasattr(self.system, 'id'):
-            seed = system.id
+            self.seed = system.id
         else:
-            seed = None
+            self.seed = None
 
         try:
             # TODO (vshnayder): move as much as possible of this work and error
             # checking to descriptor load time
             self.lcp = LoncapaProblem(self.definition['data'], self.location.html_id(),
-                                      instance_state, seed=seed, system=self.system)
+                                      instance_state, seed=self.seed, system=self.system)
         except Exception as err:
             msg = 'cannot create LoncapaProblem {loc}: {err}'.format(
                 loc=self.location.url(), err=err)
@@ -160,7 +161,7 @@ class CapaModule(XModule):
                                 (self.location.url(), msg))
                 self.lcp = LoncapaProblem(
                     problem_text, self.location.html_id(),
-                    instance_state, seed=seed, system=self.system)
+                    instance_state, seed=self.seed, system=self.system)
             else:
                 # add extra info and raise
                 raise Exception(msg), None, sys.exc_info()[2]
@@ -220,9 +221,10 @@ class CapaModule(XModule):
         try:
             html = self.lcp.get_html()
         except Exception, err:
+            log.exception(err)
+
             # TODO (vshnayder): another switch on DEBUG.
             if self.system.DEBUG:
-                log.exception(err)
                 msg = (
                     '[courseware.capa.capa_module] <font size="+1" color="red">'
                     'Failed to generate HTML for problem %s</font>' %
@@ -231,7 +233,47 @@ class CapaModule(XModule):
                 msg += '<p><pre>%s</pre></p>' % traceback.format_exc().replace('<', '&lt;')
                 html = msg
             else:
-                raise
+                # We're in non-debug mode, and possibly even in production. We want
+                #   to avoid bricking of problem as much as possible
+
+                # Presumably, student submission has corrupted LoncapaProblem HTML.
+                #   First, pull down all student answers
+                student_answers = self.lcp.student_answers
+                answer_ids = student_answers.keys()
+
+                # Some inputtypes, such as dynamath, have additional "hidden" state that
+                #   is not exposed to the student. Keep those hidden
+                # TODO: Use regex, e.g. 'dynamath' is suffix at end of answer_id
+                hidden_state_keywords = ['dynamath']
+                for answer_id in answer_ids:
+                    for hidden_state_keyword in hidden_state_keywords:
+                        if answer_id.find(hidden_state_keyword) >= 0:
+                            student_answers.pop(answer_id)
+
+                #   Next, generate a fresh LoncapaProblem
+                self.lcp = LoncapaProblem(self.definition['data'], self.location.html_id(),
+                               state=None, # Tabula rasa
+                               seed=self.seed, system=self.system)
+
+                # Prepend a scary warning to the student
+                warning  = '<div class="capa_reset">'\
+                           '<h2>Warning: The problem has been reset to its initial state!</h2>'\
+                           'The problem\'s state was corrupted by an invalid submission. ' \
+                           'The submission consisted of:'\
+                           '<ul>'
+                for student_answer in student_answers.values():
+                    if student_answer != '':
+                        warning += '<li>' + cgi.escape(student_answer) + '</li>'
+                warning += '</ul>'\
+                           'If this error persists, please contact the course staff.'\
+                           '</div>'
+
+                html = warning
+                try:
+                    html += self.lcp.get_html()
+                except Exception, err: # Couldn't do it. Give up
+                    log.exception(err)
+                    raise
 
         content = {'name': self.display_name,
                    'html': html,

common/lib/xmodule/xmodule/css/capa/display.scss

@@ -465,6 +465,22 @@ section.problem {
     margin-top: 10px;
   }
 
+  div.capa_reset {
+    padding: 25px;
+    border: 1px solid $error-red;
+    background-color: lighten($error-red, 25%);
+    border-radius: 3px;
+    font-size: 1em;
+    margin-top: 10px;
+    margin-bottom: 10px;
+  }
+  .capa_reset>h2 {
+    color: #AA0000;
+  }
+  .capa_reset li {
+    font-size: 0.9em;
+  }
+
   .hints {
     border: 1px solid #ccc;