Display specific error messages when parts of the courseware break, rather than returning a 500 indicating that the whole site is down

djangoapps/courseware/views.py

@@ -1,5 +1,6 @@
 import logging
 import urllib
+import json
 
 from django.conf import settings
 from django.core.context_processors import csrf
@@ -16,6 +17,7 @@ from lxml import etree
 from module_render import render_module, make_track_function, I4xSystem
 from models import StudentModule
 from student.models import UserProfile
+from util.errors import record_exception
 
 import courseware.content_parser as content_parser
 import courseware.modules
@@ -98,12 +100,16 @@ def render_section(request, section):
     if not settings.COURSEWARE_ENABLED:
         return redirect('/')
 
-#    try: 
-    dom = content_parser.section_file(user, section)
-    #except:
-     #   raise Http404
+    try:
+        dom = content_parser.section_file(user, section)
+    except:
+        record_exception(log, "Unable to parse courseware xml")
+        return render_to_response('courseware-error.html', {})
 
-    accordion=render_accordion(request, '', '', '')
+    context = {
+        'csrf': csrf(request)['csrf_token'],
+        'accordion': render_accordion(request, '', '', '')
+    }
 
     module_ids = dom.xpath("//@id")
     
@@ -113,15 +119,20 @@ def render_section(request, section):
     else:
         module_object_preload = []
     
-    module=render_module(user, request, dom, module_object_preload)
+    try:
+        module = render_module(user, request, dom, module_object_preload)
+    except:
+        record_exception(log, "Unable to load module")
+        context.update({
+            'init': '',
+            'content': render_to_string("module-error.html", {}),
+        })
+        return render_to_response('courseware.html', context)
 
-    if 'init_js' not in module:
-        module['init_js']=''
-
-    context={'init':module['init_js'],
-             'accordion':accordion,
-             'content':module['content'],
-             'csrf':csrf(request)['csrf_token']}
+    context.update({
+        'init':module.get('init_js', ''),
+        'content':module['content'],
+    })
 
     result = render_to_response('courseware.html', context)
     return result
@@ -147,20 +158,20 @@ def index(request, course="6.002 Spring 2012", chapter="Using the System", secti
     if course!="6.002 Spring 2012":
         return redirect('/')
 
-    #import logging
-    #log = logging.getLogger("mitx")
-    #log.info(  "DEBUG: "+str(user) )
+    try:
+        dom = content_parser.course_file(user)
+    except:
+        record_exception(log, "Unable to parse courseware xml")
+        return render_to_response('courseware-error.html', {})
 
-    dom = content_parser.course_file(user)
     dom_module = dom.xpath("//course[@name=$course]/chapter[@name=$chapter]//section[@name=$section]/*[1]", 
                            course=course, chapter=chapter, section=section)
+
     if len(dom_module) == 0:
         module = None
     else:
         module = dom_module[0]
 
-    accordion=render_accordion(request, course, chapter, section)
-
     module_ids = dom.xpath("//course[@name=$course]/chapter[@name=$chapter]//section[@name=$section]//@id", 
                            course=course, chapter=chapter, section=section)
 
@@ -169,17 +180,26 @@ def index(request, course="6.002 Spring 2012", chapter="Using the System", secti
                                                                   module_id__in=module_ids))
     else:
         module_object_preload = []
-    
 
-    module=render_module(user, request, module, module_object_preload)
+    context = {
+        'csrf': csrf(request)['csrf_token'],
+        'accordion': render_accordion(request, course, chapter, section)
+    }
 
-    if 'init_js' not in module:
-        module['init_js']=''
+    try:
+        module = render_module(user, request, module, module_object_preload)
+    except:
+        record_exception(log, "Unable to load module")
+        context.update({
+            'init': '',
+            'content': render_to_string("module-error.html", {}),
+        })
+        return render_to_response('courseware.html', context)
 
-    context={'init':module['init_js'],
-             'accordion':accordion,
-             'content':module['content'],
-             'csrf':csrf(request)['csrf_token']}
+    context.update({
+        'init': module.get('init_js', ''),
+        'content': module['content'],
+    })
 
     result = render_to_response('courseware.html', context)
     return result
@@ -215,10 +235,17 @@ def modx_dispatch(request, module=None, dispatch=None, id=None):
                        ajax_url = ajax_url,
                        filestore = None
                        )
-    instance=courseware.modules.get_module_class(module)(system, 
-                                                         xml, 
-                                                         id, 
-                                                         state=oldstate)
+
+    try:
+        instance=courseware.modules.get_module_class(module)(system, 
+                                                             xml, 
+                                                             id, 
+                                                             state=oldstate)
+    except:
+        record_exception(log, "Unable to load module during ajax call")
+        response = HttpResponse(json.dumps({'success': "We're sorry, this module is temporarily unavailable. Our staff is working to fix it as soon as possible"}))
+        return response
+
     # Let the module handle the AJAX
     ajax_return=instance.handle_ajax(dispatch, request.POST)
     # Save the state back to the database

lib/util/errors.py

@@ -0,0 +1,7 @@
+import newrelic.agent
+import sys
+
+def record_exception(logger, msg, params={}, ignore_errors=[]):
+    logger.exception(msg)
+    newrelic.agent.record_exception(*sys.exc_info())
+

requirements.txt

@@ -18,3 +18,4 @@ fs
 django-jasmine
 beautifulsoup
 requests
+newrelic

templates/courseware-error.html

@@ -0,0 +1,44 @@
+<%inherit file="main.html" />
+<%block name="bodyclass">courseware</%block>
+<%block name="title"><title>Courseware – MITx 6.002x</title></%block>
+
+<%block name="headextra">
+<script type="text/javascript" src="/static/js/flot/jquery.flot.js"></script>
+</%block>
+
+<%block name="js_extra">
+##Is there a reason this isn't in header_extra? Is it important that the javascript is at the bottom of the generated document?
+<!-- TODO: http://docs.jquery.com/Plugins/Validation -->
+<script type="text/javascript">
+  $(function() {
+    ${init}
+
+    $(".sequence-nav li a").hover(function(){
+      $(this).siblings().toggleClass("shown");
+      });
+  });
+</script>
+</%block>
+
+<%include file="navigation.html" args="active_page='courseware'" />
+
+<section class="main-content">
+  <div class="course-wrapper">
+    <section class="course-index">
+      <header id="open_close_accordion">
+        <h2>Courseware Index</h2>
+        <a href="#">close</a>
+      </header>
+
+      <div id="accordion">
+        <nav>
+          ${accordion}
+        </nav>
+      </div>
+    </section>
+
+    <section class="course-content">
+      ${content}
+    </section>
+  </div>
+</section>

templates/module-error.html

@@ -0,0 +1,4 @@
+<section class="outside-app">
+  <h1>There has been an error on the <em>MITx</em> servers</h1>
+  <p>We're sorry, this module is temporarily unavailable. Our staff is working to fix it as soon as possible. Please email us at <a href="mailto:technical@mitx.mit.edu">technical@mitx.mit.edu</a> to report any problems or downtime.</p>
+</section>