give some debug message regarding why export might fail

Conflicts:

	common/lib/xmodule/xmodule/raw_module.py

cms/djangoapps/contentstore/views/assets.py

@@ -3,6 +3,7 @@ import json
 import os
 import tarfile
 import shutil
+import cgi
 from tempfile import mkdtemp
 from path import path
 
@@ -27,7 +28,7 @@ from xmodule.modulestore import Location
 from xmodule.contentstore.content import StaticContent
 from xmodule.util.date_utils import get_default_time_display
 from xmodule.modulestore import InvalidLocationError
-from xmodule.exceptions import NotFoundError
+from xmodule.exceptions import NotFoundError, SerializationError
 
 from ..utils import get_url_reverse
 from .access import get_location_and_verify_access
@@ -332,16 +333,34 @@ def generate_export_course(request, org, course, name):
     the course
     """
     location = get_location_and_verify_access(request, org, course, name)
-
+    course_module = modulestore().get_item(location)
     loc = Location(location)
     export_file = NamedTemporaryFile(prefix=name + '.', suffix=".tar.gz")
 
     root_dir = path(mkdtemp())
 
-    # export out to a tempdir
-    logging.debug('root = {0}'.format(root_dir))
-
+    try:
         export_to_xml(modulestore('direct'), contentstore(), loc, root_dir, name, modulestore())
+    except SerializationError, e:
+        failed_item = modulestore().get_item(e.location)
+        parent_locs = modulestore().get_parent_locations(failed_item.location, None)
+        if len(parent_locs) > 0:
+            parent = modulestore().get_item(parent_locs[0])
+            parent_info = "Parent Display Name: {0}<br />Parent Identifier: {1}".format(parent.display_name, parent.location.name)
+        else:
+            parent_info = ''
+        return render_to_response('export.html', {
+            'context_course': course_module,
+            'successful_import_redirect_url': '',
+            'err_msg': "A courseware module has failed to convert to XML. Details: <br />Module Type: {0}<br />Display Name: {1}<br />Identifier: {2}<br />{3}".
+            format(failed_item.location.category, failed_item.display_name, failed_item.location.name, parent_info)
+        })
+    except Exception, e:
+        return render_to_response('export.html', {
+            'context_course': course_module,
+            'successful_import_redirect_url': '',
+            'err_msg': str(e)
+        })
 
     logging.debug('tar file being generated at {0}'.format(export_file.name))
     tar_file = tarfile.open(name=export_file.name, mode='w:gz')

cms/templates/export.html

@@ -6,6 +6,24 @@
 <%block name="title">${_("Course Export")}</%block>
 <%block name="bodyclass">is-signedin course tools export</%block>
 
+<%block name="jsextra">
+  % if err_msg:
+  <script type='text/javascript'>
+    $(document).ready(function() {
+      var defaultTitle = gettext('There has been an error with your export.');
+      var msg = "${err_msg}";
+      dialog = new CMS.Views.Alert.Confirmation({
+          title: defaultTitle,
+          message: msg,
+          intent: "error",
+          closeIcon: false
+      });
+      dialog.show();
+    })
+  </script>
+  %endif
+</%block>
+
 <%block name="content">
 <div class="wrapper-mast wrapper">
   <header class="mast has-subtitle">
@@ -18,6 +36,7 @@
 
 <div class="main-wrapper">
   <div class="inner-wrapper">
+
     <article class="export-overview">
       <div class="description">
         <h2>${_("About Exporting Courses")}</h2>

common/lib/xmodule/xmodule/exceptions.py

@@ -13,6 +13,7 @@ class ProcessingError(Exception):
     '''
     pass
 
+
 class InvalidVersionError(Exception):
     """
     Tried to save an item with a location that a store cannot support (e.g., draft version
@@ -21,3 +22,12 @@ class InvalidVersionError(Exception):
     def __init__(self, location):
         super(InvalidVersionError, self).__init__()
         self.location = location
+
+
+class SerializationError(Exception):
+    """
+    Thrown when a module cannot be exported to XML
+    """
+    def __init__(self, location, msg):
+        super(SerializationError, self).__init__(msg)
+        self.location = location

common/lib/xmodule/xmodule/raw_module.py

@@ -4,6 +4,7 @@ from xmodule.xml_module import XmlDescriptor
 import logging
 import sys
 from xblock.core import String, Scope
+from exceptions import SerializationError
 
 log = logging.getLogger(__name__)
 
@@ -27,8 +28,27 @@ class RawDescriptor(XmlDescriptor, XMLEditingDescriptor):
             # re-raise
             lines = self.data.split('\n')
             line, offset = err.position
-            msg = ("Unable to create xml for problem {loc}. "
+            msg = ("Unable to create xml for module {loc}. "
                    "Context: '{context}'".format(
                    context=lines[line - 1][offset - 40:offset + 40],
                    loc=self.location))
-            raise Exception, msg, sys.exc_info()[2]
+            raise SerializationError(self.location, msg)
+
+
+class EmptyDataRawDescriptor(XmlDescriptor, XMLEditingDescriptor):
+    """
+    Version of RawDescriptor for modules which may have no XML data,
+    but use XMLEditingDescriptor for import/export handling.
+    """
+    data = String(default='', scope=Scope.content)
+
+    @classmethod
+    def definition_from_xml(cls, xml_object, system):
+        if len(xml_object) == 0 and len(xml_object.items()) == 0:
+            return {'data': ''}, []
+        return {'data': etree.tostring(xml_object, pretty_print=True, encoding='unicode')}, []
+
+    def definition_to_xml(self, resource_fs):
+        if self.data:
+            return etree.fromstring(self.data)
+        return etree.Element(self.category)