Helper functions for Open edX (to be run in an LMS Django shell)

edx_block_helpers.py

from urlparse import urlparse, parse_qs
from collections import namedtuple

from django.core.urlresolvers import resolve
from django.contrib.auth.models import User

from courseware.model_data import FieldDataCache, DjangoKeyValueStore
from courseware.module_render import get_module_for_descriptor_internal
from courseware.courses import get_course_with_access, get_course_by_id
from opaque_keys.edx.keys import CourseKey, UsageKey
from opaque_keys.edx.locations import SlashSeparatedCourseKey
from xblock.runtime import KvsFieldData
from xmodule.modulestore.django import modulestore


VERTICAL_ID_QS_KEY = 'activate_block_id'
ProblemUrl = namedtuple('ProblemUrl', ['course', 'chapter', 'section', 'vertical'])


def get_block_descriptors(user, block_ids):
    for block_id in block_ids:
        usage_key = UsageKey.from_string(block_id)
        simple_block_descriptor = modulestore().get_item(usage_key)
        field_data_cache = FieldDataCache.cache_for_descriptor_descendents(course_key, user, simple_block_descriptor)
        student_kvs = DjangoKeyValueStore(field_data_cache)
        student_data = KvsFieldData(student_kvs)
        yield get_module_for_descriptor_internal(
            user,
            descriptor=simple_block_descriptor,
            student_data=student_data,
            course_id=usage_key.course_key,
            track_function=lambda: None,
            xqueue_callback_url_prefix='',
            request_token=None
        )


def parse_problem_url(problem_url):
    parsed_url = urlparse(problem_url)
    qs_dict = parse_qs(parsed_url.query)
    parsed_url = urlparse(problem_url)
    relative_problem_url = parsed_url.path
    if not relative_problem_url.startswith("/"):
        relative_problem_url = "/{}".format(relative_problem_url)
    resolved_url = resolve(relative_problem_url)
    course_key = SlashSeparatedCourseKey.from_deprecated_string(resolved_url.kwargs['course_id'])
    course = get_course_by_id(course_key)
    chapter = next(c for c in course.get_children() if c.scope_ids.usage_id.block_id == resolved_url.kwargs['chapter'])
    section = next(s for s in chapter.get_children() if s.scope_ids.usage_id.block_id == resolved_url.kwargs['section'])
    vertical_usage_id_str = qs_dict['activate_block_id'][0]
    vertical = next(v for v in section.get_children() if str(v.scope_ids.usage_id) == vertical_usage_id_str)
    return ProblemUrl(
        course=course,
        chapter=chapter,
        section=section,
        vertical=vertical,
    )


def get_problem_display_names(user, block_ids):
    """
    Example usage:
      get_problem_display_names(
        User.objects.get(username='edx'),
        [
          'block-v1:ODL+CS101+F2018+type@problem+block@d1c9cec328c8480aa0bcb03493b46262',
          'block-v1:ODL+CS102+F2018+type@problem+block@d1c9cec328c8480aa0bcb03493b46263',
        ]
      )
    """
    return [
        block_descriptor.display_name
        for block_descriptor in get_block_descriptors(user, block_ids)
    ]


def get_problem_answer_ids(user, block_id):
    """
    Example usage:
      get_problem_answer_ids(
        User.objects.get(username='edx'),
        'block-v1:ODL+CS101+F2018+type@problem+block@d1c9cec328c8480aa0bcb03493b46262'
      )
    """
    block_descriptor = next(get_block_descriptors(user, [block_id]))
    tree = block_descriptor.lcp.tree
    choicegroup_id = tree.xpath('//choicegroup')[0].get("id")
    answer_ids = [choice.get("name") for choice in tree.xpath('//choicegroup/choice')]
    return {
        'choicegroup_id': choicegroup_id,
        'answer_ids': answer_ids
    }


def get_problem_block_id_from_url(problem_url, problem_display_name):
    """
    Example usage:
      get_problem_block_id_from_url(
        'http://localhost:18000/courses/<course_id>/courseware/<chapter_id>/<section_id>/1?activate_block_id=<vertical_id>',
        'Problem #3'
      )
    """
    parsed_problem_url = parse_problem_url(problem_url)
    try:
        problem = next(p for p in parsed_problem_url.vertical.get_children() if p.display_name == problem_display_name)
    except StopIteration:
        raise ValueError("No problem found with the given name ({})".format(problem_display_name))
    return str(problem.location)