Merge pull request #1065 from edx/aed/EDUCATOR-1817

EDUCATOR-1817 | be defensive about serializing training examples, log…

openassessment/xblock/xml.py

@@ -2,6 +2,7 @@
 Serialize and deserialize OpenAssessment XBlock content to/from XML.
 """
 from uuid import uuid4 as uuid
+import logging
 
 import dateutil.parser
 import defusedxml.ElementTree as safe_etree
@@ -11,6 +12,9 @@ import pytz
 from openassessment.xblock.data_conversion import update_assessments_format
 
 
+log = logging.getLogger(__name__)
+
+
 class UpdateFromXmlError(Exception):
     """
     Error occurred while deserializing the OpenAssessment XBlock content from XML.
@@ -606,9 +610,21 @@ def serialize_training_examples(examples, assessment_el):
 
         # Answer provided in the example (default to empty string)
         answer_el = etree.SubElement(example_el, 'answer')
-        for part in example_dict.get('answer', {}).get('parts', []):
-            part_el = etree.SubElement(answer_el, 'part')
-            part_el.text = unicode(part.get('text', u''))
+        try:
+            answer = example_dict.get('answer')
+            if answer is None:
+                parts = []
+            elif isinstance(answer, dict):
+                parts = answer.get('parts', [])
+            elif isinstance(answer, list):
+                parse = answer
+
+            for part in example_dict.get('answer', {}).get('parts', []):
+                part_el = etree.SubElement(answer_el, 'part')
+                part_el.text = unicode(part.get('text', u''))
+        except: # excuse the bare-except, looking for more information on EDUCATOR-1817
+            log.exception('Error parsing training exapmle: %s', example_dict)
+            raise
 
         # Options selected from the rubric
         options_selected = example_dict.get('options_selected', [])