Throw error if messaging queue is not available

lms/djangoapps/instructor/tests/test_api.py

@@ -52,7 +52,11 @@ from lms.djangoapps.instructor.views.api import (
     generate_unique_password,
     require_finance_admin
 )
-from lms.djangoapps.instructor_task.api_helper import AlreadyRunningError
+from lms.djangoapps.instructor_task.api_helper import (
+    AlreadyRunningError,
+    QueueConnectionError,
+    generate_already_running_error_message
+)
 from openedx.core.djangoapps.course_groups.cohorts import set_course_cohorted
 from openedx.core.djangoapps.site_configuration import helpers as configuration_helpers
 from openedx.core.djangoapps.site_configuration.tests.mixins import SiteMixin
@@ -143,6 +147,7 @@ REPORTS_DATA = (
 EXECUTIVE_SUMMARY_DATA = (
     {
         'report_type': 'executive summary',
+        'task_type': 'exec_summary_report',
         'instructor_api_endpoint': 'get_exec_summary_report',
         'task_api_endpoint': 'lms.djangoapps.instructor_task.api.submit_executive_summary_report',
         'extra_instructor_api_kwargs': {}
@@ -244,7 +249,16 @@ def view_alreadyrunningerror(request):  # pylint: disable=unused-argument
     raise AlreadyRunningError()
 
 
+@common_exceptions_400
+def view_queue_connection_error(request):  # pylint: disable=unused-argument
+    """
+    A dummy view that raises a QueueConnectionError exception.
+    """
+    raise QueueConnectionError()
+
+
 @attr(shard=1)
+@ddt.ddt
 class TestCommonExceptions400(TestCase):
     """
     Testing the common_exceptions_400 decorator.
@@ -269,21 +283,29 @@ class TestCommonExceptions400(TestCase):
         self.request.is_ajax.return_value = True
         resp = view_user_doesnotexist(self.request)  # pylint: disable=assignment-from-no-return
         self.assertEqual(resp.status_code, 400)
-        result = json.loads(resp.content)
-        self.assertIn("User does not exist", result["error"])
+        self.assertIn("User does not exist", resp.content)
 
     def test_alreadyrunningerror(self):
         self.request.is_ajax.return_value = False
         resp = view_alreadyrunningerror(self.request)  # pylint: disable=assignment-from-no-return
         self.assertEqual(resp.status_code, 400)
-        self.assertIn("Task is already running", resp.content)
+        self.assertIn("Requested task is already running", resp.content)
 
     def test_alreadyrunningerror_ajax(self):
         self.request.is_ajax.return_value = True
         resp = view_alreadyrunningerror(self.request)  # pylint: disable=assignment-from-no-return
         self.assertEqual(resp.status_code, 400)
-        result = json.loads(resp.content)
-        self.assertIn("Task is already running", result["error"])
+        self.assertIn("Requested task is already running", resp.content)
+
+    @ddt.data(True, False)
+    def test_queue_connection_error(self, is_ajax):
+        """
+        Tests that QueueConnectionError exception is handled in common_exception_400.
+        """
+        self.request.is_ajax.return_value = is_ajax
+        resp = view_queue_connection_error(self.request)  # pylint: disable=assignment-from-no-return
+        self.assertEqual(resp.status_code, 400)
+        self.assertIn('Error occured. Please try again later', resp.content)
 
 
 @attr(shard=1)
@@ -401,6 +423,7 @@ class TestInstructorAPIDenyLevels(SharedModuleStoreTestCase, LoginEnrollmentTest
             ('get_proctored_exam_results', {}),
             ('get_problem_responses', {}),
             ('export_ora2_data', {}),
+
         ]
         # Endpoints that only Instructors can access
         self.instructor_level_endpoints = [
@@ -2680,14 +2703,15 @@ class TestInstructorAPILevelsDataDump(SharedModuleStoreTestCase, LoginEnrollment
             'get_problem_responses',
             kwargs={'course_id': unicode(self.course.id)}
         )
-
+        task_type = 'problem_responses_csv'
+        already_running_status = generate_already_running_error_message(task_type)
         with patch('lms.djangoapps.instructor_task.api.submit_calculate_problem_responses_csv') as submit_task_function:
-            error = AlreadyRunningError()
+            error = AlreadyRunningError(already_running_status)
             submit_task_function.side_effect = error
             response = self.client.post(url, {})
-            res_json = json.loads(response.content)
-            self.assertIn('status', res_json)
-            self.assertIn('already in progress', res_json['status'])
+
+        self.assertEqual(response.status_code, 400)
+        self.assertIn(already_running_status, response.content)
 
     def test_get_students_features(self):
         """
@@ -2757,17 +2781,16 @@ class TestInstructorAPILevelsDataDump(SharedModuleStoreTestCase, LoginEnrollment
         )
         # Successful case:
         response = self.client.post(url, {})
-        res_json = json.loads(response.content)
-        self.assertIn('status', res_json)
-        self.assertNotIn('currently being created', res_json['status'])
+        self.assertEqual(response.status_code, 200)
         # CSV generation already in progress:
+        task_type = 'may_enroll_info_csv'
+        already_running_status = generate_already_running_error_message(task_type)
         with patch('lms.djangoapps.instructor_task.api.submit_calculate_may_enroll_csv') as submit_task_function:
-            error = AlreadyRunningError()
+            error = AlreadyRunningError(already_running_status)
             submit_task_function.side_effect = error
             response = self.client.post(url, {})
-            res_json = json.loads(response.content)
-            self.assertIn('status', res_json)
-            self.assertIn('currently being created', res_json['status'])
+        self.assertEqual(response.status_code, 400)
+        self.assertIn(already_running_status, response.content)
 
     def test_get_student_exam_results(self):
         """
@@ -2778,19 +2801,19 @@ class TestInstructorAPILevelsDataDump(SharedModuleStoreTestCase, LoginEnrollment
             'get_proctored_exam_results',
             kwargs={'course_id': unicode(self.course.id)}
         )
+
         # Successful case:
         response = self.client.post(url, {})
-        res_json = json.loads(response.content)
-        self.assertIn('status', res_json)
-        self.assertNotIn('currently being created', res_json['status'])
+        self.assertEqual(response.status_code, 200)
         # CSV generation already in progress:
+        task_type = 'proctored_exam_results_report'
+        already_running_status = generate_already_running_error_message(task_type)
         with patch('lms.djangoapps.instructor_task.api.submit_proctored_exam_results_report') as submit_task_function:
-            error = AlreadyRunningError()
+            error = AlreadyRunningError(already_running_status)
             submit_task_function.side_effect = error
             response = self.client.post(url, {})
-            res_json = json.loads(response.content)
-            self.assertIn('status', res_json)
-            self.assertIn('currently being created', res_json['status'])
+            self.assertEqual(response.status_code, 400)
+            self.assertIn(already_running_status, response.content)
 
     def test_access_course_finance_admin_with_invalid_course_key(self):
         """
@@ -3045,10 +3068,11 @@ class TestInstructorAPILevelsDataDump(SharedModuleStoreTestCase, LoginEnrollment
     def test_executive_summary_report_success(
             self,
             report_type,
+            task_type,
             instructor_api_endpoint,
             task_api_endpoint,
             extra_instructor_api_kwargs
-    ):
+    ):  # pylint: disable=unused-argument
         kwargs = {'course_id': unicode(self.course.id)}
         kwargs.update(extra_instructor_api_kwargs)
         url = reverse(instructor_api_endpoint, kwargs=kwargs)
@@ -3066,6 +3090,7 @@ class TestInstructorAPILevelsDataDump(SharedModuleStoreTestCase, LoginEnrollment
     def test_executive_summary_report_already_running(
             self,
             report_type,
+            task_type,
             instructor_api_endpoint,
             task_api_endpoint,
             extra_instructor_api_kwargs
@@ -3075,14 +3100,12 @@ class TestInstructorAPILevelsDataDump(SharedModuleStoreTestCase, LoginEnrollment
         url = reverse(instructor_api_endpoint, kwargs=kwargs)
 
         CourseFinanceAdminRole(self.course.id).add_users(self.instructor)
+        already_running_status = generate_already_running_error_message(task_type)
         with patch(task_api_endpoint) as mock:
-            mock.side_effect = AlreadyRunningError()
+            mock.side_effect = AlreadyRunningError(already_running_status)
             response = self.client.post(url, {})
-        already_running_status = "The {report_type} report is currently being created." \
-                                 " To view the status of the report, see Pending Tasks below." \
-                                 " You will be able to download the report" \
-                                 " when it is" \
-                                 " complete.".format(report_type=report_type)
+
+        self.assertEqual(response.status_code, 400)
         self.assertIn(already_running_status, response.content)
 
     def test_get_ora2_responses_success(self):
@@ -3091,16 +3114,19 @@ class TestInstructorAPILevelsDataDump(SharedModuleStoreTestCase, LoginEnrollment
         with patch('lms.djangoapps.instructor_task.api.submit_export_ora2_data') as mock_submit_ora2_task:
             mock_submit_ora2_task.return_value = True
             response = self.client.post(url, {})
-        success_status = "The ORA data report is being generated."
+        success_status = "The ORA data report is being created."
         self.assertIn(success_status, response.content)
 
     def test_get_ora2_responses_already_running(self):
         url = reverse('export_ora2_data', kwargs={'course_id': unicode(self.course.id)})
+        task_type = 'export_ora2_data'
+        already_running_status = generate_already_running_error_message(task_type)
 
         with patch('lms.djangoapps.instructor_task.api.submit_export_ora2_data') as mock_submit_ora2_task:
-            mock_submit_ora2_task.side_effect = AlreadyRunningError()
+            mock_submit_ora2_task.side_effect = AlreadyRunningError(already_running_status)
             response = self.client.post(url, {})
-        already_running_status = "An ORA data report generation task is already in progress."
+
+        self.assertEqual(response.status_code, 400)
         self.assertIn(already_running_status, response.content)
 
     def test_get_student_progress_url(self):

lms/djangoapps/instructor/views/api.py

@@ -71,7 +71,7 @@ from lms.djangoapps.instructor.enrollment import (
 from lms.djangoapps.instructor.views import INVOICE_KEY
 from lms.djangoapps.instructor.views.instructor_task_helpers import extract_email_features, extract_task_features
 from lms.djangoapps.instructor_task.api import submit_override_score
-from lms.djangoapps.instructor_task.api_helper import AlreadyRunningError
+from lms.djangoapps.instructor_task.api_helper import AlreadyRunningError, QueueConnectionError
 from lms.djangoapps.instructor_task.models import ReportStore
 from openedx.core.djangoapps.content.course_overviews.models import CourseOverview
 from openedx.core.djangoapps.course_groups.cohorts import is_course_cohorted
@@ -133,29 +133,31 @@ log = logging.getLogger(__name__)
 
 TASK_SUBMISSION_OK = 'created'
 
+SUCCESS_MESSAGE_TEMPLATE = _("The {report_type} report is being created. "
+                             "To view the status of the report, see Pending Tasks below.")
+
 
 def common_exceptions_400(func):
     """
     Catches common exceptions and renders matching 400 errors.
     (decorator without arguments)
     """
+
     def wrapped(request, *args, **kwargs):  # pylint: disable=missing-docstring
         use_json = (request.is_ajax() or
                     request.META.get("HTTP_ACCEPT", "").startswith("application/json"))
         try:
             return func(request, *args, **kwargs)
         except User.DoesNotExist:
-            message = _("User does not exist.")
-            if use_json:
-                return JsonResponse({"error": message}, 400)
-            else:
-                return HttpResponseBadRequest(message)
-        except AlreadyRunningError:
-            message = _("Task is already running.")
+            message = _('User does not exist.')
+        except (AlreadyRunningError, QueueConnectionError) as err:
+            message = str(err)
+
         if use_json:
-                return JsonResponse({"error": message}, 400)
+            return JsonResponseBadRequest(message)
         else:
             return HttpResponseBadRequest(message)
+
     return wrapped
 
 
@@ -829,12 +831,12 @@ def bulk_beta_modify_access(request, course_id):
 @ensure_csrf_cookie
 @cache_control(no_cache=True, no_store=True, must_revalidate=True)
 @require_level('instructor')
-@common_exceptions_400
 @require_post_params(
     unique_student_identifier="email or username of user to change access",
     rolename="'instructor', 'staff', 'beta', or 'ccx_coach'",
     action="'allow' or 'revoke'"
 )
+@common_exceptions_400
 def modify_access(request, course_id):
     """
     Modify staff/instructor access of other user.
@@ -964,6 +966,7 @@ def list_course_role_members(request, course_id):
 @ensure_csrf_cookie
 @cache_control(no_cache=True, no_store=True, must_revalidate=True)
 @require_level('staff')
+@common_exceptions_400
 def get_problem_responses(request, course_id):
     """
     Initiate generation of a CSV file containing all student answers
@@ -978,6 +981,7 @@ def get_problem_responses(request, course_id):
     """
     course_key = CourseKey.from_string(course_id)
     problem_location = request.POST.get('problem_location', '')
+    report_type = _('problem responses')
 
     try:
         problem_key = UsageKey.from_string(problem_location)
@@ -990,20 +994,10 @@ def get_problem_responses(request, course_id):
     except InvalidKeyError:
         return JsonResponseBadRequest(_("Could not find problem with this location."))
 
-    try:
     lms.djangoapps.instructor_task.api.submit_calculate_problem_responses_csv(request, course_key, problem_location)
-        success_status = _(
-            "The problem responses report is being created."
-            " To view the status of the report, see Pending Tasks below."
-        )
+    success_status = SUCCESS_MESSAGE_TEMPLATE.format(report_type=report_type)
+
     return JsonResponse({"status": success_status})
-    except AlreadyRunningError:
-        already_running_status = _(
-            "A problem responses report generation task is already in progress. "
-            "Check the 'Pending Tasks' table for the status of the task. "
-            "When completed, the report will be available for download in the table below."
-        )
-        return JsonResponse({"status": already_running_status})
 
 
 @require_POST
@@ -1209,6 +1203,7 @@ def get_issued_certificates(request, course_id):
 @ensure_csrf_cookie
 @cache_control(no_cache=True, no_store=True, must_revalidate=True)
 @require_level('staff')
+@common_exceptions_400
 def get_students_features(request, course_id, csv=False):  # pylint: disable=redefined-outer-name
     """
     Respond with json which contains a summary of all enrolled students profile information.
@@ -1220,7 +1215,7 @@ def get_students_features(request, course_id, csv=False):  # pylint: disable=red
     """
     course_key = CourseKey.from_string(course_id)
     course = get_course_by_id(course_key)
-
+    report_type = _('enrolled learner profile')
     available_features = instructor_analytics.basic.AVAILABLE_FEATURES
 
     # Allow for sites to be able to define additional columns.
@@ -1285,22 +1280,16 @@ def get_students_features(request, course_id, csv=False):  # pylint: disable=red
             'available_features': available_features,
         }
         return JsonResponse(response_payload)
+
     else:
-        try:
         lms.djangoapps.instructor_task.api.submit_calculate_students_features_csv(
             request,
             course_key,
             query_features
         )
-            success_status = _("The enrolled learner profile report is being created."
-                               " To view the status of the report, see Pending Tasks below.")
+        success_status = SUCCESS_MESSAGE_TEMPLATE.format(report_type=report_type)
+
         return JsonResponse({"status": success_status})
-        except AlreadyRunningError:
-            already_running_status = _(
-                "This enrollment report is currently being created."
-                " To view the status of the report, see Pending Tasks below."
-                " You will be able to download the report when it is complete.")
-            return JsonResponse({"status": already_running_status})
 
 
 @transaction.non_atomic_requests
@@ -1308,6 +1297,7 @@ def get_students_features(request, course_id, csv=False):  # pylint: disable=red
 @ensure_csrf_cookie
 @cache_control(no_cache=True, no_store=True, must_revalidate=True)
 @require_level('staff')
+@common_exceptions_400
 def get_students_who_may_enroll(request, course_id):
     """
     Initiate generation of a CSV file containing information about
@@ -1319,21 +1309,11 @@ def get_students_who_may_enroll(request, course_id):
     """
     course_key = CourseKey.from_string(course_id)
     query_features = ['email']
-    try:
+    report_type = _('enrollment')
     lms.djangoapps.instructor_task.api.submit_calculate_may_enroll_csv(request, course_key, query_features)
-        success_status = _(
-            "The enrollment report is being created. This report contains"
-            " information about learners who can enroll in the course."
-            " To view the status of the report, see Pending Tasks below."
-        )
+    success_status = SUCCESS_MESSAGE_TEMPLATE.format(report_type=report_type)
+
     return JsonResponse({"status": success_status})
-    except AlreadyRunningError:
-        already_running_status = _(
-            "This enrollment report is currently being created."
-            " To view the status of the report, see Pending Tasks below."
-            " You will be able to download the report when it is complete."
-        )
-        return JsonResponse({"status": already_running_status})
 
 
 @transaction.non_atomic_requests
@@ -1341,6 +1321,7 @@ def get_students_who_may_enroll(request, course_id):
 @cache_control(no_cache=True, no_store=True, must_revalidate=True)
 @require_POST
 @require_level('staff')
+@common_exceptions_400
 def add_users_to_cohorts(request, course_id):
     """
     View method that accepts an uploaded file (using key "uploaded-file")
@@ -1417,23 +1398,17 @@ def get_coupon_codes(request, course_id):  # pylint: disable=unused-argument
 @cache_control(no_cache=True, no_store=True, must_revalidate=True)
 @require_level('staff')
 @require_finance_admin
+@common_exceptions_400
 def get_enrollment_report(request, course_id):
     """
     get the enrollment report for the particular course.
     """
     course_key = SlashSeparatedCourseKey.from_deprecated_string(course_id)
-    try:
+    report_type = _('detailed enrollment')
     lms.djangoapps.instructor_task.api.submit_detailed_enrollment_features_csv(request, course_key)
-        success_status = _("The detailed enrollment report is being created."
-                           " To view the status of the report, see Pending Tasks below.")
+    success_status = SUCCESS_MESSAGE_TEMPLATE.format(report_type=report_type)
+
     return JsonResponse({"status": success_status})
-    except AlreadyRunningError:
-        already_running_status = _("The detailed enrollment report is being created."
-                                   " To view the status of the report, see Pending Tasks below."
-                                   " You will be able to download the report when it is complete.")
-        return JsonResponse({
-            "status": already_running_status
-        })
 
 
 @transaction.non_atomic_requests
@@ -1442,24 +1417,17 @@ def get_enrollment_report(request, course_id):
 @cache_control(no_cache=True, no_store=True, must_revalidate=True)
 @require_level('staff')
 @require_finance_admin
+@common_exceptions_400
 def get_exec_summary_report(request, course_id):
     """
     get the executive summary report for the particular course.
     """
     course_key = SlashSeparatedCourseKey.from_deprecated_string(course_id)
-    try:
+    report_type = _('executive summary')
     lms.djangoapps.instructor_task.api.submit_executive_summary_report(request, course_key)
-        status_response = _("The executive summary report is being created."
-                            " To view the status of the report, see Pending Tasks below.")
-    except AlreadyRunningError:
-        status_response = _(
-            "The executive summary report is currently being created."
-            " To view the status of the report, see Pending Tasks below."
-            " You will be able to download the report when it is complete."
-        )
-    return JsonResponse({
-        "status": status_response
-    })
+    success_status = SUCCESS_MESSAGE_TEMPLATE.format(report_type=report_type)
+
+    return JsonResponse({"status": success_status})
 
 
 @transaction.non_atomic_requests
@@ -1467,24 +1435,17 @@ def get_exec_summary_report(request, course_id):
 @ensure_csrf_cookie
 @cache_control(no_cache=True, no_store=True, must_revalidate=True)
 @require_level('staff')
+@common_exceptions_400
 def get_course_survey_results(request, course_id):
     """
     get the survey results report for the particular course.
     """
     course_key = SlashSeparatedCourseKey.from_deprecated_string(course_id)
-    try:
+    report_type = _('survey')
     lms.djangoapps.instructor_task.api.submit_course_survey_report(request, course_key)
-        status_response = _("The survey report is being created."
-                            " To view the status of the report, see Pending Tasks below.")
-    except AlreadyRunningError:
-        status_response = _(
-            "The survey report is currently being created."
-            " To view the status of the report, see Pending Tasks below."
-            " You will be able to download the report when it is complete."
-        )
-    return JsonResponse({
-        "status": status_response
-    })
+    success_status = SUCCESS_MESSAGE_TEMPLATE.format(report_type=report_type)
+
+    return JsonResponse({"status": success_status})
 
 
 @transaction.non_atomic_requests
@@ -1492,6 +1453,7 @@ def get_course_survey_results(request, course_id):
 @ensure_csrf_cookie
 @cache_control(no_cache=True, no_store=True, must_revalidate=True)
 @require_level('staff')
+@common_exceptions_400
 def get_proctored_exam_results(request, course_id):
     """
     get the proctored exam resultsreport for the particular course.
@@ -1508,19 +1470,11 @@ def get_proctored_exam_results(request, course_id):
     ]
 
     course_key = CourseKey.from_string(course_id)
-    try:
+    report_type = _('proctored exam results')
     lms.djangoapps.instructor_task.api.submit_proctored_exam_results_report(request, course_key, query_features)
-        status_response = _("The proctored exam results report is being created."
-                            " To view the status of the report, see Pending Tasks below.")
-    except AlreadyRunningError:
-        status_response = _(
-            "The proctored exam results report is currently being created."
-            " To view the status of the report, see Pending Tasks below."
-            " You will be able to download the report when it is complete."
-        )
-    return JsonResponse({
-        "status": status_response
-    })
+    success_status = SUCCESS_MESSAGE_TEMPLATE.format(report_type=report_type)
+
+    return JsonResponse({"status": success_status})
 
 
 def save_registration_code(user, course_id, mode_slug, invoice=None, order=None, invoice_item=None):
@@ -1901,11 +1855,11 @@ def get_anon_ids(request, course_id):  # pylint: disable=unused-argument
 @require_POST
 @ensure_csrf_cookie
 @cache_control(no_cache=True, no_store=True, must_revalidate=True)
-@common_exceptions_400
 @require_level('staff')
 @require_post_params(
     unique_student_identifier="email or username of student for whom to get progress url"
 )
+@common_exceptions_400
 def get_student_progress_url(request, course_id):
     """
     Get the progress url of a student.
@@ -2147,6 +2101,7 @@ def rescore_problem(request, course_id):
             )
         except NotImplementedError as exc:
             return HttpResponseBadRequest(exc.message)
+
     elif all_students:
         try:
             lms.djangoapps.instructor_task.api.submit_rescore_problem_for_all_students(
@@ -2453,25 +2408,17 @@ def list_financial_report_downloads(_request, course_id):
 @ensure_csrf_cookie
 @cache_control(no_cache=True, no_store=True, must_revalidate=True)
 @require_level('staff')
+@common_exceptions_400
 def export_ora2_data(request, course_id):
     """
     Pushes a Celery task which will aggregate ora2 responses for a course into a .csv
     """
     course_key = SlashSeparatedCourseKey.from_deprecated_string(course_id)
-    try:
+    report_type = _('ORA data')
     lms.djangoapps.instructor_task.api.submit_export_ora2_data(request, course_key)
-        success_status = _("The ORA data report is being generated.")
+    success_status = SUCCESS_MESSAGE_TEMPLATE.format(report_type=report_type)
 
     return JsonResponse({"status": success_status})
-    except AlreadyRunningError:
-        already_running_status = _(
-            "An ORA data report generation task is already in "
-            "progress. Check the 'Pending Tasks' table "
-            "for the status of the task. When completed, the report "
-            "will be available for download in the table below."
-        )
-
-        return JsonResponse({"status": already_running_status})
 
 
 @transaction.non_atomic_requests
@@ -2479,21 +2426,17 @@ def export_ora2_data(request, course_id):
 @ensure_csrf_cookie
 @cache_control(no_cache=True, no_store=True, must_revalidate=True)
 @require_level('staff')
+@common_exceptions_400
 def calculate_grades_csv(request, course_id):
     """
     AlreadyRunningError is raised if the course's grades are already being updated.
     """
+    report_type = _('grade')
     course_key = SlashSeparatedCourseKey.from_deprecated_string(course_id)
-    try:
     lms.djangoapps.instructor_task.api.submit_calculate_grades_csv(request, course_key)
-        success_status = _("The grade report is being created."
-                           " To view the status of the report, see Pending Tasks below.")
+    success_status = SUCCESS_MESSAGE_TEMPLATE.format(report_type=report_type)
+
     return JsonResponse({"status": success_status})
-    except AlreadyRunningError:
-        already_running_status = _("The grade report is currently being created."
-                                   " To view the status of the report, see Pending Tasks below."
-                                   " You will be able to download the report when it is complete.")
-        return JsonResponse({"status": already_running_status})
 
 
 @transaction.non_atomic_requests
@@ -2501,6 +2444,7 @@ def calculate_grades_csv(request, course_id):
 @ensure_csrf_cookie
 @cache_control(no_cache=True, no_store=True, must_revalidate=True)
 @require_level('staff')
+@common_exceptions_400
 def problem_grade_report(request, course_id):
     """
     Request a CSV showing students' grades for all problems in the
@@ -2510,18 +2454,11 @@ def problem_grade_report(request, course_id):
     updated.
     """
     course_key = SlashSeparatedCourseKey.from_deprecated_string(course_id)
-    try:
+    report_type = _('problem grade')
     lms.djangoapps.instructor_task.api.submit_problem_grade_report(request, course_key)
-        success_status = _("The problem grade report is being created."
-                           " To view the status of the report, see Pending Tasks below.")
+    success_status = SUCCESS_MESSAGE_TEMPLATE.format(report_type=report_type)
+
     return JsonResponse({"status": success_status})
-    except AlreadyRunningError:
-        already_running_status = _("A problem grade report is already being generated."
-                                   " To view the status of the report, see Pending Tasks below."
-                                   " You will be able to download the report when it is complete.")
-        return JsonResponse({
-            "status": already_running_status
-        })
 
 
 @require_POST
@@ -2601,6 +2538,7 @@ def list_forum_members(request, course_id):
 @cache_control(no_cache=True, no_store=True, must_revalidate=True)
 @require_level('staff')
 @require_post_params(send_to="sending to whom", subject="subject line", message="message text")
+@common_exceptions_400
 def send_email(request, course_id):
     """
     Send an email to self, staff, cohorts, or everyone involved in a course.
@@ -2667,6 +2605,7 @@ def send_email(request, course_id):
         'course_id': course_id.to_deprecated_string(),
         'success': True,
     }
+
     return JsonResponse(response_payload)
 
 
@@ -2944,6 +2883,7 @@ def mark_student_can_skip_entrance_exam(request, course_id):  # pylint: disable=
 @cache_control(no_cache=True, no_store=True, must_revalidate=True)
 @require_global_staff
 @require_POST
+@common_exceptions_400
 def start_certificate_generation(request, course_id):
     """
     Start generating certificates for all students enrolled in given course.
@@ -2956,6 +2896,7 @@ def start_certificate_generation(request, course_id):
         'message': message,
         'task_id': task.task_id
     }
+
     return JsonResponse(response_payload)
 
 
@@ -2964,6 +2905,7 @@ def start_certificate_generation(request, course_id):
 @cache_control(no_cache=True, no_store=True, must_revalidate=True)
 @require_global_staff
 @require_POST
+@common_exceptions_400
 def start_certificate_regeneration(request, course_id):
     """
     Start regenerating certificates for students whose certificate statuses lie with in 'certificate_statuses'
@@ -2990,11 +2932,8 @@ def start_certificate_regeneration(request, course_id):
             {'message': _('Please select certificate statuses from the list only.')},
             status=400
         )
-    try:
-        lms.djangoapps.instructor_task.api.regenerate_certificates(request, course_key, certificates_statuses)
-    except AlreadyRunningError as error:
-        return JsonResponse({'message': error.message}, status=400)
 
+    lms.djangoapps.instructor_task.api.regenerate_certificates(request, course_key, certificates_statuses)
     response_payload = {
         'message': _('Certificate regeneration task has been started. '
                      'You can view the status of the generation task in the "Pending Tasks" section.'),
@@ -3183,6 +3122,7 @@ def get_student(username_or_email, course_key):
 @cache_control(no_cache=True, no_store=True, must_revalidate=True)
 @require_global_staff
 @require_POST
+@common_exceptions_400
 def generate_certificate_exceptions(request, course_id, generate_for=None):
     """
     Generate Certificate for students in the Certificate White List.
@@ -3213,7 +3153,6 @@ def generate_certificate_exceptions(request, course_id, generate_for=None):
         )
 
     lms.djangoapps.instructor_task.api.generate_certificates_for_students(request, course_key, student_set=students)
-
     response_payload = {
         'success': True,
         'message': _('Certificate generation started for white listed students.'),
@@ -3401,6 +3340,7 @@ def invalidate_certificate(request, generated_certificate, certificate_invalidat
     }
 
 
+@common_exceptions_400
 def re_validate_certificate(request, course_key, generated_certificate):
     """
     Remove certificate invalidation from db and start certificate generation task for this student.
@@ -3421,6 +3361,7 @@ def re_validate_certificate(request, course_key, generated_certificate):
 
     # We need to generate certificate only for a single student here
     student = certificate_invalidation.generated_certificate.user
+
     lms.djangoapps.instructor_task.api.generate_certificates_for_students(
         request, course_key, student_set="specific_student", specific_student_id=student.id
     )

lms/djangoapps/instructor_task/api_helper.py

@@ -25,7 +25,26 @@ log = logging.getLogger(__name__)
 
 class AlreadyRunningError(Exception):
     """Exception indicating that a background task is already running"""
-    pass
+
+    message = _('Requested task is already running')
+
+    def __init__(self, message=None):
+
+        if not message:
+            message = self.message
+        super(AlreadyRunningError, self).__init__(message)
+
+
+class QueueConnectionError(Exception):
+    """
+    Exception indicating that celery task was not created successfully.
+    """
+    message = _('Error occured. Please try again later.')
+
+    def __init__(self, message=None):
+        if not message:
+            message = self.message
+        super(QueueConnectionError, self).__init__(message)
 
 
 def _task_is_running(course_id, task_type, task_key):
@@ -57,7 +76,8 @@ def _reserve_task(course_id, task_type, task_key, task_input, requester):
 
     if _task_is_running(course_id, task_type, task_key):
         log.warning("Duplicate task found for task_type %s and task_key %s", task_type, task_key)
-        raise AlreadyRunningError("requested task is already running")
+        error_message = generate_already_running_error_message(task_type)
+        raise AlreadyRunningError(error_message)
 
     try:
         most_recent_id = InstructorTask.objects.latest('id').id
@@ -75,6 +95,37 @@ def _reserve_task(course_id, task_type, task_key, task_input, requester):
     return InstructorTask.create(course_id, task_type, task_key, task_input, requester)
 
 
+def generate_already_running_error_message(task_type):
+    """
+    Returns already running error message for given task type.
+    """
+
+    message = ''
+    report_types = {
+        'grade_problems': _('problem grade'),
+        'problem_responses_csv': _('problem responses'),
+        'profile_info_csv': _('enrolled learner profile'),
+        'may_enroll_info_csv': _('enrollment'),
+        'detailed_enrollment_report': _('detailed enrollment'),
+        'exec_summary_report': _('executive summary'),
+        'course_survey_report': _('survey'),
+        'proctored_exam_results_report': _('proctored exam results'),
+        'export_ora2_data': _('ORA data'),
+        'grade_course': _('grade'),
+
+    }
+
+    if report_types.get(task_type):
+
+        message = _(
+            "The {report_type} report is being created. "
+            "To view the status of the report, see Pending Tasks below. "
+            "You will be able to download the report when it is complete."
+        ).format(report_type=report_types.get(task_type))
+
+    return message
+
+
 def _get_xmodule_instance_args(request, task_id):
     """
     Calculate parameters needed for instantiating xmodule instances.
@@ -190,6 +241,27 @@ def _update_instructor_task(instructor_task, task_result):
             instructor_task.save()
 
 
+def _update_instructor_task_state(instructor_task, task_state, message=None):
+    """
+    Update state and output of InstructorTask object.
+    """
+    instructor_task.task_state = task_state
+    if message:
+        instructor_task.task_output = message
+
+    instructor_task.save()
+
+
+def _handle_instructor_task_failure(instructor_task, error):
+    """
+    Do required operations if task creation was not complete.
+    """
+    log.info("instructor task (%s) failed, result: %s", instructor_task.task_id, error.message)
+    _update_instructor_task_state(instructor_task, FAILURE, error.message)
+
+    raise QueueConnectionError()
+
+
 def get_updated_instructor_task(task_id):
     """
     Returns InstructorTask object corresponding to a given `task_id`.
@@ -365,6 +437,10 @@ def submit_task(request, task_type, task_class, course_key, task_input, task_key
 
     task_id = instructor_task.task_id
     task_args = [instructor_task.id, _get_xmodule_instance_args(request, task_id)]
+    try:
         task_class.apply_async(task_args, task_id=task_id)
 
+    except Exception as error:
+        _handle_instructor_task_failure(instructor_task, error)
+
     return instructor_task

lms/djangoapps/instructor_task/tests/test_api.py

@@ -32,7 +32,7 @@ from lms.djangoapps.instructor_task.api import (
     submit_reset_problem_attempts_for_all_students,
     submit_reset_problem_attempts_in_entrance_exam
 )
-from lms.djangoapps.instructor_task.api_helper import AlreadyRunningError
+from lms.djangoapps.instructor_task.api_helper import AlreadyRunningError, QueueConnectionError
 from lms.djangoapps.instructor_task.models import PROGRESS, InstructorTask
 from lms.djangoapps.instructor_task.tasks import export_ora2_data
 from lms.djangoapps.instructor_task.tests.test_base import (
@@ -43,6 +43,7 @@ from lms.djangoapps.instructor_task.tests.test_base import (
     TestReportMixin
 )
 from xmodule.modulestore.exceptions import ItemNotFoundError
+from celery.states import FAILURE
 
 
 class InstructorTaskReportTest(InstructorTaskTestCase):
@@ -164,15 +165,31 @@ class InstructorTaskModuleSubmitTest(InstructorTaskModuleTestCase):
     )
     @ddt.unpack
     def test_submit_task(self, task_function, expected_task_type, params=None):
+        """
+        Tests submission of instructor task.
+        """
         if params is None:
             params = {}
         if params.get('student'):
             params['student'] = self.student
 
-        # tests submit, and then tests a second identical submission.
         problem_url_name = 'H1P1'
         self.define_option_problem(problem_url_name)
         location = InstructorTaskModuleTestCase.problem_location(problem_url_name)
+
+        # unsuccessful submission, exception raised while submitting.
+        with patch('lms.djangoapps.instructor_task.tasks_base.BaseInstructorTask.apply_async') as apply_async:
+
+            error = Exception()
+            apply_async.side_effect = error
+
+            with self.assertRaises(QueueConnectionError):
+                instructor_task = task_function(self.create_task_request(self.instructor), location, **params)
+
+            most_recent_task = InstructorTask.objects.latest('id')
+            self.assertEquals(most_recent_task.task_state, FAILURE)
+
+        # successful submission
         instructor_task = task_function(self.create_task_request(self.instructor), location, **params)
         self.assertEquals(instructor_task.task_type, expected_task_type)
 

lms/static/js/instructor_dashboard/data_download.js

@@ -122,16 +122,18 @@
             });
             this.$proctored_exam_csv_btn.click(function() {
                 var url = dataDownloadObj.$proctored_exam_csv_btn.data('endpoint');
+                var errorMessage = gettext('Error generating proctored exam results. Please try again.');
                 return $.ajax({
                     type: 'POST',
                     dataType: 'json',
                     url: url,
-                    error: function() {
+                    error: function(error) {
+                        if (error.responseText) {
+                            errorMessage = JSON.parse(error.responseText);
+                        }
                         dataDownloadObj.clear_display();
-                        dataDownloadObj.$reports_request_response_error.text(
-                            gettext('Error generating proctored exam results. Please try again.')
-                        );
-                        return $('.msg-error').css({
+                        dataDownloadObj.$reports_request_response_error.text(errorMessage);
+                        return dataDownloadObj.$reports_request_response_error.css({
                             display: 'block'
                         });
                     },
@@ -146,16 +148,18 @@
             });
             this.$survey_results_csv_btn.click(function() {
                 var url = dataDownloadObj.$survey_results_csv_btn.data('endpoint');
+                var errorMessage = gettext('Error generating survey results. Please try again.');
                 return $.ajax({
                     type: 'POST',
                     dataType: 'json',
                     url: url,
-                    error: function() {
+                    error: function(error) {
+                        if (error.responseText) {
+                            errorMessage = JSON.parse(error.responseText);
+                        }
                         dataDownloadObj.clear_display();
-                        dataDownloadObj.$reports_request_response_error.text(
-                            gettext('Error generating survey results. Please try again.')
-                        );
-                        return $('.msg-error').css({
+                        dataDownloadObj.$reports_request_response_error.text(errorMessage);
+                        return dataDownloadObj.$reports_request_response_error.css({
                             display: 'block'
                         });
                     },
@@ -170,16 +174,18 @@
             });
             this.$list_studs_csv_btn.click(function() {
                 var url = dataDownloadObj.$list_studs_csv_btn.data('endpoint') + '/csv';
+                var errorMessage = gettext('Error generating student profile information. Please try again.');
                 dataDownloadObj.clear_display();
                 return $.ajax({
                     type: 'POST',
                     dataType: 'json',
                     url: url,
-                    error: function() {
-                        dataDownloadObj.$reports_request_response_error.text(
-                            gettext('Error generating student profile information. Please try again.')
-                        );
-                        return $('.msg-error').css({
+                    error: function(error) {
+                        if (error.responseText) {
+                            errorMessage = JSON.parse(error.responseText);
+                        }
+                        dataDownloadObj.$reports_request_response_error.text(errorMessage);
+                        return dataDownloadObj.$reports_request_response_error.css({
                             display: 'block'
                         });
                     },
@@ -201,9 +207,13 @@
                     url: url,
                     error: function() {
                         dataDownloadObj.clear_display();
-                        return dataDownloadObj.$download_request_response_error.text(
+                        dataDownloadObj.$download_request_response_error.text(
                             gettext('Error getting student list.')
                         );
+                        return dataDownloadObj.$download_request_response_error.css({
+                            display: 'block'
+                        });
+
                     },
                     success: function(data) {
                         var $tablePlaceholder, columns, feature, gridData, options;
@@ -251,7 +261,7 @@
                         dataDownloadObj.$reports_request_response_error.text(
                             JSON.parse(error.responseText)
                         );
-                        return $('.msg-error').css({
+                        return dataDownloadObj.$reports_request_response_error.css({
                             display: 'block'
                         });
                     },
@@ -265,16 +275,18 @@
             });
             this.$list_may_enroll_csv_btn.click(function() {
                 var url = dataDownloadObj.$list_may_enroll_csv_btn.data('endpoint');
+                var errorMessage = gettext('Error generating list of students who may enroll. Please try again.');
                 dataDownloadObj.clear_display();
                 return $.ajax({
                     type: 'POST',
                     dataType: 'json',
                     url: url,
-                    error: function() {
-                        dataDownloadObj.$reports_request_response_error.text(
-                            gettext('Error generating list of students who may enroll. Please try again.')
-                        );
-                        return $('.msg-error').css({
+                    error: function(error) {
+                        if (error.responseText) {
+                            errorMessage = JSON.parse(error.responseText);
+                        }
+                        dataDownloadObj.$reports_request_response_error.text(errorMessage);
+                        return dataDownloadObj.$reports_request_response_error.css({
                             display: 'block'
                         });
                     },
@@ -294,9 +306,12 @@
                     url: url,
                     error: function() {
                         dataDownloadObj.clear_display();
-                        return dataDownloadObj.$download_request_response_error.text(
+                        dataDownloadObj.$download_request_response_error.text(
                             gettext('Error retrieving grading configuration.')
                         );
+                        return dataDownloadObj.$download_request_response_error.css({
+                            display: 'block'
+                        });
                     },
                     success: function(data) {
                         dataDownloadObj.clear_display();
@@ -307,29 +322,27 @@
             });
             this.$async_report_btn.click(function(e) {
                 var url = $(e.target).data('endpoint');
+                var errorMessage = '';
                 dataDownloadObj.clear_display();
                 return $.ajax({
                     type: 'POST',
                     dataType: 'json',
                     url: url,
-                    error: statusAjaxError(function() {
-                        if (e.target.name === 'calculate-grades-csv') {
-                            dataDownloadObj.$grades_request_response_error.text(
-                                gettext('Error generating grades. Please try again.')
-                            );
+                    error: function(error) {
+                        if (error.responseText) {
+                            errorMessage = JSON.parse(error.responseText);
+                        } else if (e.target.name === 'calculate-grades-csv') {
+                            errorMessage = gettext('Error generating grades. Please try again.');
                         } else if (e.target.name === 'problem-grade-report') {
-                            dataDownloadObj.$grades_request_response_error.text(
-                                gettext('Error generating problem grade report. Please try again.')
-                            );
+                            errorMessage = gettext('Error generating problem grade report. Please try again.');
                         } else if (e.target.name === 'export-ora2-data') {
-                            dataDownloadObj.$grades_request_response_error.text(
-                                gettext('Error generating ORA data report. Please try again.')
-                            );
+                            errorMessage = gettext('Error generating ORA data report. Please try again.');
                         }
-                        return $('.msg-error').css({
+                        dataDownloadObj.$reports_request_response_error.text(errorMessage);
+                        return dataDownloadObj.$reports_request_response_error.css({
                             display: 'block'
                         });
-                    }),
+                    },
                     success: function(data) {
                         dataDownloadObj.$reports_request_response.text(data.status);
                         return $('.msg-confirm').css({

lms/static/js/spec/staff_debug_actions_spec.js

@@ -96,7 +96,7 @@ define([
                         error_msg: 'Failed to reset attempts for user.'
                     };
                     StaffDebug.doInstructorDashAction(action);
-                    AjaxHelpers.respondWithError(requests);
+                    AjaxHelpers.respondWithTextError(requests);
                     expect($('#idash_msg').text()).toBe('Failed to reset attempts for user. ');
                     $('#result_' + locationName).remove();
                 });

lms/static/js/staff_debug_actions.js

@@ -54,12 +54,12 @@ var StaffDebug = (function() {
                 try {
                     responseJSON = $.parseJSON(request.responseText);
                 } catch (e) {
-                    responseJSON = {error: gettext('Unknown Error Occurred.')};
+                    responseJSON = 'Unknown Error Occurred.';
                 }
                 var text = _.template('{error_msg} {error}', {interpolate: /\{(.+?)\}/g})(
                     {
                         error_msg: action.error_msg,
-                        error: responseJSON.error
+                        error: gettext(responseJSON)
                     }
             );
                 var html = _.template('<p id="idash_msg" class="error">{text}</p>', {interpolate: /\{(.+?)\}/g})(