Files
edx-platform/common/lib/xmodule/xmodule/course_module.py

757 lines
29 KiB
Python

import logging
from cStringIO import StringIO
from math import exp, erf
from lxml import etree
from path import path # NOTE (THK): Only used for detecting presence of syllabus
import requests
import time
from datetime import datetime
from xmodule.modulestore import Location
from xmodule.seq_module import SequenceDescriptor, SequenceModule
from xmodule.timeparse import parse_time
from xmodule.util.decorators import lazyproperty
from xmodule.graders import grader_from_conf
from datetime import datetime
import json
import logging
import requests
import time
import copy
from xblock.core import Scope, ModelType, List, String, Object, Boolean
from .fields import Date
log = logging.getLogger(__name__)
class StringOrDate(Date):
def from_json(self, value):
"""
Parse an optional metadata key containing a time: if present, complain
if it doesn't parse.
Return None if not present or invalid.
"""
if value is None:
return None
try:
return time.strptime(value, self.time_format)
except ValueError:
return value
def to_json(self, value):
"""
Convert a time struct to a string
"""
if value is None:
return None
try:
return time.strftime(self.time_format, value)
except (ValueError, TypeError):
return value
edx_xml_parser = etree.XMLParser(dtd_validation=False, load_dtd=False,
remove_comments=True, remove_blank_text=True)
_cached_toc = {}
class Textbook(object):
def __init__(self, title, book_url):
self.title = title
self.book_url = book_url
self.start_page = int(self.table_of_contents[0].attrib['page'])
# The last page should be the last element in the table of contents,
# but it may be nested. So recurse all the way down the last element
last_el = self.table_of_contents[-1]
while last_el.getchildren():
last_el = last_el[-1]
self.end_page = int(last_el.attrib['page'])
@lazyproperty
def table_of_contents(self):
"""
Accesses the textbook's table of contents (default name "toc.xml") at the URL self.book_url
Returns XML tree representation of the table of contents
"""
toc_url = self.book_url + 'toc.xml'
# cdodge: I've added this caching of TOC because in Mongo-backed instances (but not Filesystem stores)
# course modules have a very short lifespan and are constantly being created and torn down.
# Since this module in the __init__() method does a synchronous call to AWS to get the TOC
# this is causing a big performance problem. So let's be a bit smarter about this and cache
# each fetch and store in-mem for 10 minutes.
# NOTE: I have to get this onto sandbox ASAP as we're having runtime failures. I'd like to swing back and
# rewrite to use the traditional Django in-memory cache.
try:
# see if we already fetched this
if toc_url in _cached_toc:
(table_of_contents, timestamp) = _cached_toc[toc_url]
age = datetime.now() - timestamp
# expire every 10 minutes
if age.seconds < 600:
return table_of_contents
except Exception as err:
pass
# Get the table of contents from S3
log.info("Retrieving textbook table of contents from %s" % toc_url)
try:
r = requests.get(toc_url)
except Exception as err:
msg = 'Error %s: Unable to retrieve textbook table of contents at %s' % (err, toc_url)
log.error(msg)
raise Exception(msg)
# TOC is XML. Parse it
try:
table_of_contents = etree.fromstring(r.text)
except Exception as err:
msg = 'Error %s: Unable to parse XML for textbook table of contents at %s' % (err, toc_url)
log.error(msg)
raise Exception(msg)
return table_of_contents
class TextbookList(List):
def from_json(self, values):
textbooks = []
for title, book_url in values:
try:
textbooks.append(Textbook(title, book_url))
except:
# If we can't get to S3 (e.g. on a train with no internet), don't break
# the rest of the courseware.
log.exception("Couldn't load textbook ({0}, {1})".format(title, book_url))
continue
return textbooks
def to_json(self, values):
json_data = []
for val in values:
if isinstance(val, Textbook):
json_data.append((val.title, val.book_url))
elif isinstance(val, tuple):
json_data.append(val)
else:
continue
return json_data
class CourseFields(object):
textbooks = TextbookList(help="List of pairs of (title, url) for textbooks used in this course", scope=Scope.content)
wiki_slug = String(help="Slug that points to the wiki for this course", scope=Scope.content)
enrollment_start = Date(help="Date that enrollment for this class is opened", scope=Scope.settings)
enrollment_end = Date(help="Date that enrollment for this class is closed", scope=Scope.settings)
start = Date(help="Start time when this module is visible", scope=Scope.settings)
end = Date(help="Date that this class ends", scope=Scope.settings)
advertised_start = StringOrDate(help="Date that this course is advertised to start", scope=Scope.settings)
grading_policy = Object(help="Grading policy definition for this class", scope=Scope.content)
show_calculator = Boolean(help="Whether to show the calculator in this course", default=False, scope=Scope.settings)
display_name = String(help="Display name for this module", scope=Scope.settings)
tabs = List(help="List of tabs to enable in this course", scope=Scope.settings)
end_of_course_survey_url = String(help="Url for the end-of-course survey", scope=Scope.settings)
discussion_blackouts = List(help="List of pairs of start/end dates for discussion blackouts", scope=Scope.settings)
discussion_topics = Object(
help="Map of topics names to ids",
scope=Scope.settings,
computed_default=lambda c: {'General': {'id': c.location.html_id()}},
)
testcenter_info = Object(help="Dictionary of Test Center info", scope=Scope.settings)
announcement = Date(help="Date this course is announced", scope=Scope.settings)
cohort_config = Object(help="Dictionary defining cohort configuration", scope=Scope.settings)
is_new = Boolean(help="Whether this course should be flagged as new", scope=Scope.settings)
no_grade = Boolean(help="True if this course isn't graded", default=False, scope=Scope.settings)
disable_progress_graph = Boolean(help="True if this course shouldn't display the progress graph", default=False, scope=Scope.settings)
pdf_textbooks = List(help="List of dictionaries containing pdf_textbook configuration", scope=Scope.settings)
html_textbooks = List(help="List of dictionaries containing html_textbook configuration", scope=Scope.settings)
remote_gradebook = Object(scope=Scope.settings)
allow_anonymous = Boolean(scope=Scope.settings, default=True)
allow_anonymous_to_peers = Boolean(scope=Scope.settings, default=False)
advanced_modules = List(help="Beta modules used in your course", scope=Scope.settings)
has_children = True
info_sidebar_name = String(scope=Scope.settings, default='Course Handouts')
# An extra property is used rather than the wiki_slug/number because
# there are courses that change the number for different runs. This allows
# courses to share the same css_class across runs even if they have
# different numbers.
#
# TODO get rid of this as soon as possible or potentially build in a robust
# way to add in course-specific styling. There needs to be a discussion
# about the right way to do this, but arjun will address this ASAP. Also
# note that the courseware template needs to change when this is removed.
css_class = String(help="DO NOT USE THIS", scope=Scope.settings)
# TODO: This is a quick kludge to allow CS50 (and other courses) to
# specify their own discussion forums as external links by specifying a
# "discussion_link" in their policy JSON file. This should later get
# folded in with Syllabus, Course Info, and additional Custom tabs in a
# more sensible framework later.
discussion_link = String(help="DO NOT USE THIS", scope=Scope.settings)
# TODO: same as above, intended to let internal CS50 hide the progress tab
# until we get grade integration set up.
# Explicit comparison to True because we always want to return a bool.
hide_progress_tab = Boolean(help="DO NOT USE THIS", scope=Scope.settings)
class CourseDescriptor(CourseFields, SequenceDescriptor):
module_class = SequenceModule
template_dir_name = 'course'
def __init__(self, *args, **kwargs):
super(CourseDescriptor, self).__init__(*args, **kwargs)
if self.wiki_slug is None:
self.wiki_slug = self.location.course
msg = None
if self.start is None:
msg = "Course loaded without a valid start date. id = %s" % self.id
# hack it -- start in 1970
self.start = time.gmtime(0)
log.critical(msg)
self.system.error_tracker(msg)
# NOTE: relies on the modulestore to call set_grading_policy() right after
# init. (Modulestore is in charge of figuring out where to load the policy from)
# NOTE (THK): This is a last-minute addition for Fall 2012 launch to dynamically
# disable the syllabus content for courses that do not provide a syllabus
self.syllabus_present = self.system.resources_fs.exists(path('syllabus'))
self._grading_policy = {}
self.set_grading_policy(self.grading_policy)
self.test_center_exams = []
test_center_info = self.testcenter_info
if test_center_info is not None:
for exam_name in test_center_info:
try:
exam_info = test_center_info[exam_name]
self.test_center_exams.append(self.TestCenterExam(self.id, exam_name, exam_info))
except Exception as err:
# If we can't parse the test center exam info, don't break
# the rest of the courseware.
msg = 'Error %s: Unable to load test-center exam info for exam "%s" of course "%s"' % (err, exam_name, self.id)
log.error(msg)
continue
def default_grading_policy(self):
"""
Return a dict which is a copy of the default grading policy
"""
return {"GRADER": [
{
"type": "Homework",
"min_count": 12,
"drop_count": 2,
"short_label": "HW",
"weight": 0.15
},
{
"type": "Lab",
"min_count": 12,
"drop_count": 2,
"weight": 0.15
},
{
"type": "Midterm Exam",
"short_label": "Midterm",
"min_count": 1,
"drop_count": 0,
"weight": 0.3
},
{
"type": "Final Exam",
"short_label": "Final",
"min_count": 1,
"drop_count": 0,
"weight": 0.4
}
],
"GRADE_CUTOFFS": {
"Pass": 0.5
}}
def set_grading_policy(self, course_policy):
"""
The JSON object can have the keys GRADER and GRADE_CUTOFFS. If either is
missing, it reverts to the default.
"""
if course_policy is None:
course_policy = {}
# Load the global settings as a dictionary
grading_policy = self.default_grading_policy()
# Override any global settings with the course settings
grading_policy.update(course_policy)
# Here is where we should parse any configurations, so that we can fail early
# Use setters so that side effecting to .definitions works
self.raw_grader = grading_policy['GRADER'] # used for cms access
self.grade_cutoffs = grading_policy['GRADE_CUTOFFS']
@classmethod
def read_grading_policy(cls, paths, system):
"""Load a grading policy from the specified paths, in order, if it exists."""
# Default to a blank policy dict
policy_str = '{}'
for policy_path in paths:
if not system.resources_fs.exists(policy_path):
continue
log.debug("Loading grading policy from {0}".format(policy_path))
try:
with system.resources_fs.open(policy_path) as grading_policy_file:
policy_str = grading_policy_file.read()
# if we successfully read the file, stop looking at backups
break
except (IOError):
msg = "Unable to load course settings file from '{0}'".format(policy_path)
log.warning(msg)
return policy_str
@classmethod
def from_xml(cls, xml_data, system, org=None, course=None):
instance = super(CourseDescriptor, cls).from_xml(xml_data, system, org, course)
# bleh, have to parse the XML here to just pull out the url_name attribute
# I don't think it's stored anywhere in the instance.
course_file = StringIO(xml_data.encode('ascii', 'ignore'))
xml_obj = etree.parse(course_file, parser=edx_xml_parser).getroot()
policy_dir = None
url_name = xml_obj.get('url_name', xml_obj.get('slug'))
if url_name:
policy_dir = 'policies/' + url_name
# Try to load grading policy
paths = ['grading_policy.json']
if policy_dir:
paths = [policy_dir + '/grading_policy.json'] + paths
try:
policy = json.loads(cls.read_grading_policy(paths, system))
except ValueError:
system.error_tracker("Unable to decode grading policy as json")
policy = {}
# cdodge: import the grading policy information that is on disk and put into the
# descriptor 'definition' bucket as a dictionary so that it is persisted in the DB
instance.grading_policy = policy
# now set the current instance. set_grading_policy() will apply some inheritance rules
instance.set_grading_policy(policy)
return instance
@classmethod
def definition_from_xml(cls, xml_object, system):
textbooks = []
for textbook in xml_object.findall("textbook"):
textbooks.append((textbook.get('title'), textbook.get('book_url')))
xml_object.remove(textbook)
#Load the wiki tag if it exists
wiki_slug = None
wiki_tag = xml_object.find("wiki")
if wiki_tag is not None:
wiki_slug = wiki_tag.attrib.get("slug", default=None)
xml_object.remove(wiki_tag)
definition, children = super(CourseDescriptor, cls).definition_from_xml(xml_object, system)
definition['textbooks'] = textbooks
definition['wiki_slug'] = wiki_slug
return definition, children
def has_ended(self):
"""
Returns True if the current time is after the specified course end date.
Returns False if there is no end date specified.
"""
if self.end is None:
return False
return time.gmtime() > self.end
def has_started(self):
return time.gmtime() > self.start
@property
def grader(self):
return grader_from_conf(self.raw_grader)
@property
def raw_grader(self):
return self._grading_policy['RAW_GRADER']
@raw_grader.setter
def raw_grader(self, value):
# NOTE WELL: this change will not update the processed graders. If we need that, this needs to call grader_from_conf
self._grading_policy['RAW_GRADER'] = value
self.grading_policy['GRADER'] = value
@property
def grade_cutoffs(self):
return self._grading_policy['GRADE_CUTOFFS']
@grade_cutoffs.setter
def grade_cutoffs(self, value):
self._grading_policy['GRADE_CUTOFFS'] = value
# XBlock fields don't update after mutation
policy = self.grading_policy
policy['GRADE_CUTOFFS'] = value
self.grading_policy = policy
@property
def lowest_passing_grade(self):
return min(self._grading_policy['GRADE_CUTOFFS'].values())
@property
def is_cohorted(self):
"""
Return whether the course is cohorted.
"""
config = self.cohort_config
if config is None:
return False
return bool(config.get("cohorted"))
@property
def auto_cohort(self):
"""
Return whether the course is auto-cohorted.
"""
if not self.is_cohorted:
return False
return bool(self.cohort_config.get(
"auto_cohort", False))
@property
def auto_cohort_groups(self):
"""
Return the list of groups to put students into. Returns [] if not
specified. Returns specified list even if is_cohorted and/or auto_cohort are
false.
"""
if self.cohort_config is None:
return []
else:
return self.cohort_config.get("auto_cohort_groups", [])
@property
def top_level_discussion_topic_ids(self):
"""
Return list of topic ids defined in course policy.
"""
topics = self.discussion_topics
return [d["id"] for d in topics.values()]
@property
def cohorted_discussions(self):
"""
Return the set of discussions that is explicitly cohorted. It may be
the empty set. Note that all inline discussions are automatically
cohorted based on the course's is_cohorted setting.
"""
config = self.cohort_config
if config is None:
return set()
return set(config.get("cohorted_discussions", []))
@property
def is_newish(self):
"""
Returns if the course has been flagged as new. If
there is no flag, return a heuristic value considering the
announcement and the start dates.
"""
flag = self.is_new
if flag is None:
# Use a heuristic if the course has not been flagged
announcement, start, now = self._sorting_dates()
if announcement and (now - announcement).days < 30:
# The course has been announced for less that month
return True
elif (now - start).days < 1:
# The course has not started yet
return True
else:
return False
elif isinstance(flag, basestring):
return flag.lower() in ['true', 'yes', 'y']
else:
return bool(flag)
@property
def sorting_score(self):
"""
Returns a tuple that can be used to sort the courses according
the how "new" they are. The "newness" score is computed using a
heuristic that takes into account the announcement and
(advertized) start dates of the course if available.
The lower the number the "newer" the course.
"""
# Make courses that have an announcement date shave a lower
# score than courses than don't, older courses should have a
# higher score.
announcement, start, now = self._sorting_dates()
scale = 300.0 # about a year
if announcement:
days = (now - announcement).days
score = -exp(-days / scale)
else:
days = (now - start).days
score = exp(days / scale)
return score
def _sorting_dates(self):
# utility function to get datetime objects for dates used to
# compute the is_new flag and the sorting_score
def to_datetime(timestamp):
return datetime(*timestamp[:6])
announcement = self.announcement
if announcement is not None:
announcement = to_datetime(announcement)
if self.advertised_start is None or isinstance(self.advertised_start, basestring):
start = to_datetime(self.start)
else:
start = to_datetime(self.advertised_start)
now = to_datetime(time.gmtime())
return announcement, start, now
@lazyproperty
def grading_context(self):
"""
This returns a dictionary with keys necessary for quickly grading
a student. They are used by grades.grade()
The grading context has two keys:
graded_sections - This contains the sections that are graded, as
well as all possible children modules that can affect the
grading. This allows some sections to be skipped if the student
hasn't seen any part of it.
The format is a dictionary keyed by section-type. The values are
arrays of dictionaries containing
"section_descriptor" : The section descriptor
"xmoduledescriptors" : An array of xmoduledescriptors that
could possibly be in the section, for any student
all_descriptors - This contains a list of all xmodules that can
effect grading a student. This is used to efficiently fetch
all the xmodule state for a ModelDataCache without walking
the descriptor tree again.
"""
all_descriptors = []
graded_sections = {}
def yield_descriptor_descendents(module_descriptor):
for child in module_descriptor.get_children():
yield child
for module_descriptor in yield_descriptor_descendents(child):
yield module_descriptor
for c in self.get_children():
sections = []
for s in c.get_children():
if s.lms.graded:
xmoduledescriptors = list(yield_descriptor_descendents(s))
xmoduledescriptors.append(s)
# The xmoduledescriptors included here are only the ones that have scores.
section_description = {'section_descriptor': s, 'xmoduledescriptors': filter(lambda child: child.has_score, xmoduledescriptors)}
section_format = s.lms.format if s.lms.format is not None else ''
graded_sections[section_format] = graded_sections.get(section_format, []) + [section_description]
all_descriptors.extend(xmoduledescriptors)
all_descriptors.append(s)
return {'graded_sections': graded_sections,
'all_descriptors': all_descriptors, }
@staticmethod
def make_id(org, course, url_name):
return '/'.join([org, course, url_name])
@staticmethod
def id_to_location(course_id):
'''Convert the given course_id (org/course/name) to a location object.
Throws ValueError if course_id is of the wrong format.
'''
org, course, name = course_id.split('/')
return Location('i4x', org, course, 'course', name)
@staticmethod
def location_to_id(location):
'''Convert a location of a course to a course_id. If location category
is not "course", raise a ValueError.
location: something that can be passed to Location
'''
loc = Location(location)
if loc.category != "course":
raise ValueError("{0} is not a course location".format(loc))
return "/".join([loc.org, loc.course, loc.name])
@property
def id(self):
"""Return the course_id for this course"""
return self.location_to_id(self.location)
@property
def start_date_text(self):
if isinstance(self.advertised_start, basestring):
return self.advertised_start
elif self.advertised_start is None and self.start is None:
return 'TBD'
else:
return time.strftime("%b %d, %Y", self.advertised_start or self.start)
@property
def end_date_text(self):
return time.strftime("%b %d, %Y", self.end)
@property
def forum_posts_allowed(self):
try:
blackout_periods = [(parse_time(start), parse_time(end))
for start, end
in self.discussion_blackouts]
now = time.gmtime()
for start, end in blackout_periods:
if start <= now <= end:
return False
except:
log.exception("Error parsing discussion_blackouts for course {0}".format(self.id))
return True
class TestCenterExam(object):
def __init__(self, course_id, exam_name, exam_info):
self.course_id = course_id
self.exam_name = exam_name
self.exam_info = exam_info
self.exam_series_code = exam_info.get('Exam_Series_Code') or exam_name
self.display_name = exam_info.get('Exam_Display_Name') or self.exam_series_code
self.first_eligible_appointment_date = self._try_parse_time('First_Eligible_Appointment_Date')
if self.first_eligible_appointment_date is None:
raise ValueError("First appointment date must be specified")
# TODO: If defaulting the last appointment date, it should be the
# *end* of the same day, not the same time. It's going to be used as the
# end of the exam overall, so we don't want the exam to disappear too soon.
# It's also used optionally as the registration end date, so time matters there too.
self.last_eligible_appointment_date = self._try_parse_time('Last_Eligible_Appointment_Date') # or self.first_eligible_appointment_date
if self.last_eligible_appointment_date is None:
raise ValueError("Last appointment date must be specified")
self.registration_start_date = self._try_parse_time('Registration_Start_Date') or time.gmtime(0)
self.registration_end_date = self._try_parse_time('Registration_End_Date') or self.last_eligible_appointment_date
# do validation within the exam info:
if self.registration_start_date > self.registration_end_date:
raise ValueError("Registration start date must be before registration end date")
if self.first_eligible_appointment_date > self.last_eligible_appointment_date:
raise ValueError("First appointment date must be before last appointment date")
if self.registration_end_date > self.last_eligible_appointment_date:
raise ValueError("Registration end date must be before last appointment date")
self.exam_url = exam_info.get('Exam_URL')
def _try_parse_time(self, key):
"""
Parse an optional metadata key containing a time: if present, complain
if it doesn't parse.
Return None if not present or invalid.
"""
if key in self.exam_info:
try:
return parse_time(self.exam_info[key])
except ValueError as e:
msg = "Exam {0} in course {1} loaded with a bad exam_info key '{2}': '{3}'".format(self.exam_name, self.course_id, self.exam_info[key], e)
log.warning(msg)
return None
def has_started(self):
return time.gmtime() > self.first_eligible_appointment_date
def has_ended(self):
return time.gmtime() > self.last_eligible_appointment_date
def has_started_registration(self):
return time.gmtime() > self.registration_start_date
def has_ended_registration(self):
return time.gmtime() > self.registration_end_date
def is_registering(self):
now = time.gmtime()
return now >= self.registration_start_date and now <= self.registration_end_date
@property
def first_eligible_appointment_date_text(self):
return time.strftime("%b %d, %Y", self.first_eligible_appointment_date)
@property
def last_eligible_appointment_date_text(self):
return time.strftime("%b %d, %Y", self.last_eligible_appointment_date)
@property
def registration_end_date_text(self):
return time.strftime("%b %d, %Y at %H:%M UTC", self.registration_end_date)
@property
def current_test_center_exam(self):
exams = [exam for exam in self.test_center_exams if exam.has_started_registration() and not exam.has_ended()]
if len(exams) > 1:
# TODO: output some kind of warning. This should already be
# caught if we decide to do validation at load time.
return exams[0]
elif len(exams) == 1:
return exams[0]
else:
return None
def get_test_center_exam(self, exam_series_code):
exams = [exam for exam in self.test_center_exams if exam.exam_series_code == exam_series_code]
return exams[0] if len(exams) == 1 else None
@property
def number(self):
return self.location.course
@property
def org(self):
return self.location.org