edx-platform/lms/djangoapps/open_ended_grading/staff_grading_service.py

"""
This module provides views that proxy to the staff grading backend service.
"""

import json
import logging

from django.conf import settings
from django.http import HttpResponse, Http404

from xmodule.course_module import CourseDescriptor
from xmodule.open_ended_grading_classes.grading_service_module import GradingService, GradingServiceError

from courseware.access import has_access
from lms.lib.xblock.runtime import LmsModuleSystem
from mitxmako.shortcuts import render_to_string
from student.models import unique_id_for_user
from util.json_request import expect_json

from open_ended_grading.utils import does_location_exist

log = logging.getLogger(__name__)

STAFF_ERROR_MESSAGE = 'Could not contact the external grading server.  Please contact the development team.  If you do not have a point of contact, you can contact Vik at vik@edx.org.'


class MockStaffGradingService(object):
    """
    A simple mockup of a staff grading service, testing.
    """

    def __init__(self):
        self.cnt = 0

    def get_next(self, course_id, location, grader_id):
        self.cnt += 1
        return json.dumps({'success': True,
                           'submission_id': self.cnt,
                           'submission': 'Test submission {cnt}'.format(cnt=self.cnt),
                           'num_graded': 3,
                           'min_for_ml': 5,
                           'num_pending': 4,
                           'prompt': 'This is a fake prompt',
                           'ml_error_info': 'ML info',
                           'max_score': 2 + self.cnt % 3,
                           'rubric': 'A rubric'})

    def get_problem_list(self, course_id, grader_id):
        self.cnt += 1
        return json.dumps({'success': True,
                           'problem_list': [
                               json.dumps({'location': 'i4x://MITx/3.091x/problem/open_ended_demo1',
                                           'problem_name': "Problem 1", 'num_graded': 3, 'num_pending': 5,
                                           'min_for_ml': 10}),
                               json.dumps({'location': 'i4x://MITx/3.091x/problem/open_ended_demo2',
                                           'problem_name': "Problem 2", 'num_graded': 1, 'num_pending': 5,
                                           'min_for_ml': 10})
                           ]})


    def save_grade(self, course_id, grader_id, submission_id, score, feedback, skipped, rubric_scores,
                   submission_flagged):
        return self.get_next(course_id, 'fake location', grader_id)


class StaffGradingService(GradingService):
    """
    Interface to staff grading backend.
    """

    def __init__(self, config):
        config['system'] = LmsModuleSystem(
            static_url='/static',
            track_function=None,
            get_module = None,
            render_template=render_to_string,
            replace_urls=None,
        )
        super(StaffGradingService, self).__init__(config)
        self.url = config['url'] + config['staff_grading']
        self.login_url = self.url + '/login/'
        self.get_next_url = self.url + '/get_next_submission/'
        self.save_grade_url = self.url + '/save_grade/'
        self.get_problem_list_url = self.url + '/get_problem_list/'
        self.get_notifications_url = self.url + "/get_notifications/"


    def get_problem_list(self, course_id, grader_id):
        """
        Get the list of problems for a given course.

        Args:
            course_id: course id that we want the problems of
            grader_id: who is grading this?  The anonymous user_id of the grader.

        Returns:
            json string with the response from the service.  (Deliberately not
            writing out the fields here--see the docs on the staff_grading view
            in the grading_controller repo)

        Raises:
            GradingServiceError: something went wrong with the connection.
        """
        params = {'course_id': course_id, 'grader_id': grader_id}
        return self.get(self.get_problem_list_url, params)


    def get_next(self, course_id, location, grader_id):
        """
        Get the next thing to grade.

        Args:
            course_id: the course that this problem belongs to
            location: location of the problem that we are grading and would like the
                next submission for
            grader_id: who is grading this?  The anonymous user_id of the grader.

        Returns:
            json string with the response from the service.  (Deliberately not
            writing out the fields here--see the docs on the staff_grading view
            in the grading_controller repo)

        Raises:
            GradingServiceError: something went wrong with the connection.
        """
        response = self.get(self.get_next_url,
                            params={'location': location,
                                    'grader_id': grader_id})
        return json.dumps(self._render_rubric(response))


    def save_grade(self, course_id, grader_id, submission_id, score, feedback, skipped, rubric_scores,
                   submission_flagged):
        """
        Save a score and feedback for a submission.

        Returns:
            json dict with keys
                'success': bool
                'error': error msg, if something went wrong.

        Raises:
            GradingServiceError if there's a problem connecting.
        """
        data = {'course_id': course_id,
                'submission_id': submission_id,
                'score': score,
                'feedback': feedback,
                'grader_id': grader_id,
                'skipped': skipped,
                'rubric_scores': rubric_scores,
                'rubric_scores_complete': True,
                'submission_flagged': submission_flagged}

        return self.post(self.save_grade_url, data=data)

    def get_notifications(self, course_id):
        params = {'course_id': course_id}
        response = self.get(self.get_notifications_url, params)
        return response


# don't initialize until staff_grading_service() is called--means that just
# importing this file doesn't create objects that may not have the right config
_service = None


def staff_grading_service():
    """
    Return a staff grading service instance--if settings.MOCK_STAFF_GRADING is True,
    returns a mock one, otherwise a real one.

    Caches the result, so changing the setting after the first call to this
    function will have no effect.
    """
    global _service
    if _service is not None:
        return _service

    if settings.MOCK_STAFF_GRADING:
        _service = MockStaffGradingService()
    else:
        _service = StaffGradingService(settings.OPEN_ENDED_GRADING_INTERFACE)

    return _service


def _err_response(msg):
    """
    Return a HttpResponse with a json dump with success=False, and the given error message.
    """
    return HttpResponse(json.dumps({'success': False, 'error': msg}),
                        mimetype="application/json")


def _check_access(user, course_id):
    """
    Raise 404 if user doesn't have staff access to course_id
    """
    course_location = CourseDescriptor.id_to_location(course_id)
    if not has_access(user, course_location, 'staff'):
        raise Http404

    return


def get_next(request, course_id):
    """
    Get the next thing to grade for course_id and with the location specified
    in the request.

    Returns a json dict with the following keys:

    'success': bool

    'submission_id': a unique identifier for the submission, to be passed back
                     with the grade.

    'submission': the submission, rendered as read-only html for grading

    'rubric': the rubric, also rendered as html.

    'message': if there was no submission available, but nothing went wrong,
            there will be a message field.

    'error': if success is False, will have an error message with more info.
    """
    _check_access(request.user, course_id)

    required = set(['location'])
    if request.method != 'POST':
        raise Http404
    actual = set(request.POST.keys())
    missing = required - actual
    if len(missing) > 0:
        return _err_response('Missing required keys {0}'.format(
            ', '.join(missing)))
    grader_id = unique_id_for_user(request.user)
    p = request.POST
    location = p['location']

    return HttpResponse(_get_next(course_id, grader_id, location),
                        mimetype="application/json")

def get_problem_list(request, course_id):
    """
    Get all the problems for the given course id

    Returns a json dict with the following keys:
        success: bool

        problem_list: a list containing json dicts with the following keys:
            each dict represents a different problem in the course

            location: the location of the problem

            problem_name: the name of the problem

            num_graded: the number of responses that have been graded

            num_pending: the number of responses that are sitting in the queue

            min_for_ml: the number of responses that need to be graded before
                the ml can be run

        'error': if success is False, will have an error message with more info.
    """
    _check_access(request.user, course_id)
    try:
        response = staff_grading_service().get_problem_list(course_id, unique_id_for_user(request.user))
        response = json.loads(response)

        # If 'problem_list' is in the response, then we got a list of problems from the ORA server.
        # If it is not, then ORA could not find any problems.
        if 'problem_list' in response:
            problem_list = response['problem_list']
        else:
            problem_list = []
            # Make an error messages to reflect that we could not find anything to grade.
            response['error'] = ("Cannot find any open response problems in this course.  "
                                 "Have you submitted answers to any open response assessment questions?  "
                                 "If not, please do so and return to this page.")
        valid_problem_list = []
        for i in xrange(0,len(problem_list)):
            # Needed to ensure that the 'location' key can be accessed.
            try:
                problem_list[i] = json.loads(problem_list[i])
            except Exception:
                pass
            if does_location_exist(course_id, problem_list[i]['location']):
                valid_problem_list.append(problem_list[i])
        response['problem_list'] = valid_problem_list
        response = json.dumps(response)

        return HttpResponse(response,
                            mimetype="application/json")
    except GradingServiceError:
        #This is a dev_facing_error
        log.exception(
            "Error from staff grading service in open "
            "ended grading.  server url: {0}".format(staff_grading_service().url)
        )
        #This is a staff_facing_error
        return HttpResponse(json.dumps({'success': False,
                                        'error': STAFF_ERROR_MESSAGE}))


def _get_next(course_id, grader_id, location):
    """
    Implementation of get_next (also called from save_grade) -- returns a json string
    """
    try:
        return staff_grading_service().get_next(course_id, location, grader_id)
    except GradingServiceError:
        #This is a dev facing error
        log.exception(
            "Error from staff grading service in open "
            "ended grading.  server url: {0}".format(staff_grading_service().url)
        )
        #This is a staff_facing_error
        return json.dumps({'success': False,
                           'error': STAFF_ERROR_MESSAGE})


def save_grade(request, course_id):
    """
    Save the grade and feedback for a submission, and, if all goes well, return
    the next thing to grade.

    Expects the following POST parameters:
    'score': int
    'feedback': string
    'submission_id': int

    Returns the same thing as get_next, except that additional error messages
    are possible if something goes wrong with saving the grade.
    """
    _check_access(request.user, course_id)

    if request.method != 'POST':
        raise Http404
    p = request.POST
    required = set(['score', 'feedback', 'submission_id', 'location', 'submission_flagged'])
    skipped = 'skipped' in p
    #If the instructor has skipped grading the submission, then there will not be any rubric scores.
    #Only add in the rubric scores if the instructor has not skipped.
    if not skipped:
        required|=set(['rubric_scores[]'])
    actual = set(p.keys())
    missing = required - actual
    if len(missing) > 0:
        return _err_response('Missing required keys {0}'.format(
            ', '.join(missing)))

    grader_id = unique_id_for_user(request.user)


    location = p['location']


    try:
        result_json = staff_grading_service().save_grade(course_id,
                                                         grader_id,
                                                         p['submission_id'],
                                                         p['score'],
                                                         p['feedback'],
                                                         skipped,
                                                         p.getlist('rubric_scores[]'),
                                                         p['submission_flagged'])
    except GradingServiceError:
        #This is a dev_facing_error
        log.exception(
            "Error saving grade in the staff grading interface in open ended grading.  Request: {0} Course ID: {1}".format(
                request, course_id))
        #This is a staff_facing_error
        return _err_response(STAFF_ERROR_MESSAGE)

    try:
        result = json.loads(result_json)
    except ValueError:
        #This is a dev_facing_error
        log.exception(
            "save_grade returned broken json in the staff grading interface in open ended grading: {0}".format(
                result_json))
        #This is a staff_facing_error
        return _err_response(STAFF_ERROR_MESSAGE)

    if not result.get('success', False):
        #This is a dev_facing_error
        log.warning(
            'Got success=False from staff grading service in open ended grading.  Response: {0}'.format(result_json))
        return _err_response(STAFF_ERROR_MESSAGE)

    # Ok, save_grade seemed to work.  Get the next submission to grade.
    return HttpResponse(_get_next(course_id, grader_id, location),
                        mimetype="application/json")