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"""
This file contains the logic for cohort groups, as exposed internally to the
forums, and to the cohort admin views.
"""
from courseware import courses
from student.models import get_user_by_username_or_email
from .models import CourseUserGroup
log = logging.getLogger(__name__)
# tl;dr: global state is bad. capa reseeds random every time a problem is loaded. Even
# if and when that's fixed, it's a good idea to have a local generator to avoid any other
# code that messes with the global random module.
_local_random = None
def local_random():
"""
Get the local random number generator. In a function so that we don't run
random.Random() at import time.
"""
# ironic, isn't it?
global _local_random
if _local_random is None:
_local_random = random.Random()
return _local_random
def is_course_cohorted(course_id):
"""
Given a course id, return a boolean for whether or not the course is
cohorted.
Raises:
Http404 if the course doesn't exist.
"""
return courses.get_course_by_id(course_id).is_cohorted
def get_cohort_id(user, course_id):
"""
Given a course id and a user, return the id of the cohort that user is
assigned to in that course. If they don't have a cohort, return None.
"""
cohort = get_cohort(user, course_id)
return None if cohort is None else cohort.id
def is_commentable_cohorted(course_id, commentable_id):
"""
Args:
course_id: string
commentable_id: string
Returns:
Bool: is this commentable cohorted?
Raises:
Http404 if the course doesn't exist.
"""
course = courses.get_course_by_id(course_id)
if not course.is_cohorted:
# this is the easy case :)
ans = False
elif commentable_id in course.top_level_discussion_topic_ids:
# top level discussions have to be manually configured as cohorted
# (default is not)
ans = commentable_id in course.cohorted_discussions
else:
# inline discussions are cohorted by default
ans = True
log.debug("is_commentable_cohorted({0}, {1}) = {2}".format(course_id,
commentable_id,
ans))
return ans
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def get_cohorted_commentables(course_id):
"""
Given a course_id return a list of strings representing cohorted commentables
"""
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course = courses.get_course_by_id(course_id)
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if not course.is_cohorted:
# this is the easy case :)
ans = []
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ans = course.cohorted_discussions
return ans
def get_cohort(user, course_id):
"""
Given a django User and a course_id, return the user's cohort in that
cohort.
Arguments:
user: a Django User object.
course_id: string in the format 'org/course/run'
Returns:
A CourseUserGroup object if the course is cohorted and the User has a
cohort, else None.
Raises:
ValueError if the course_id doesn't exist.
# First check whether the course is cohorted (users shouldn't be in a cohort
# in non-cohorted courses, but settings can change after course starts)
try:
course = courses.get_course_by_id(course_id)
except Http404:
raise ValueError("Invalid course_id")
if not course.is_cohorted:
return None
return CourseUserGroup.objects.get(course_id=course_id,
group_type=CourseUserGroup.COHORT,
users__id=user.id)
except CourseUserGroup.DoesNotExist:
# Didn't find the group. We'll go on to create one if needed.
pass
if not course.auto_cohort:
return None
choices = course.auto_cohort_groups
n = len(choices)
if n == 0:
# Nowhere to put user
log.warning("Course %s is auto-cohorted, but there are no"
" auto_cohort_groups specified",
course_id)
return None
# Put user in a random group, creating it if needed
group_name = local_random().choice(choices)
group, created = CourseUserGroup.objects.get_or_create(
course_id=course_id,
group_type=CourseUserGroup.COHORT,
name=group_name)
user.course_groups.add(group)
return group
def get_course_cohorts(course_id):
"""
Get a list of all the cohorts in the given course.
Arguments:
course_id: string in the format 'org/course/run'
Returns:
A list of CourseUserGroup objects. Empty if there are no cohorts. Does
not check whether the course is cohorted.
"""
return list(CourseUserGroup.objects.filter(course_id=course_id,
group_type=CourseUserGroup.COHORT))
### Helpers for cohort management views
def get_cohort_by_name(course_id, name):
"""
Return the CourseUserGroup object for the given cohort. Raises DoesNotExist
it isn't present.
"""
return CourseUserGroup.objects.get(course_id=course_id,
group_type=CourseUserGroup.COHORT,
name=name)
def get_cohort_by_id(course_id, cohort_id):
"""
Return the CourseUserGroup object for the given cohort. Raises DoesNotExist
it isn't present. Uses the course_id for extra validation...
"""
return CourseUserGroup.objects.get(course_id=course_id,
group_type=CourseUserGroup.COHORT,
id=cohort_id)
def add_cohort(course_id, name):
"""
Add a cohort to a course. Raises ValueError if a cohort of the same name already
exists.
"""
log.debug("Adding cohort %s to %s", name, course_id)
if CourseUserGroup.objects.filter(course_id=course_id,
group_type=CourseUserGroup.COHORT,
name=name).exists():
raise ValueError("Can't create two cohorts with the same name")
return CourseUserGroup.objects.create(course_id=course_id,
group_type=CourseUserGroup.COHORT,
name=name)
class CohortConflict(Exception):
"""
Raised when user to be added is already in another cohort in same course.
"""
pass
def add_user_to_cohort(cohort, username_or_email):
"""
Look up the given user, and if successful, add them to the specified cohort.
Arguments:
cohort: CourseUserGroup
username_or_email: string. Treated as email if has '@'
Returns:
User object.
Raises:
User.DoesNotExist if can't find user.
ValueError if user already present in this cohort.
CohortConflict if user already in another cohort.
user = get_user_by_username_or_email(username_or_email)
# If user in any cohorts in this course already, complain
course_cohorts = CourseUserGroup.objects.filter(
course_id=cohort.course_id,
users__id=user.id,
group_type=CourseUserGroup.COHORT)
if course_cohorts.exists():
if course_cohorts[0] == cohort:
raise ValueError("User {0} already present in cohort {1}".format(
user.username,
cohort.name))
else:
raise CohortConflict("User {0} is in another cohort {1} in course"
.format(user.username,
course_cohorts[0].name))
cohort.users.add(user)
return user
def get_course_cohort_names(course_id):
"""
Return a list of the cohort names in a course.
"""
return [c.name for c in get_course_cohorts(course_id)]
def delete_empty_cohort(course_id, name):
"""
Remove an empty cohort. Raise ValueError if cohort is not empty.
"""
cohort = get_cohort_by_name(course_id, name)
if cohort.users.exists():
raise ValueError(
"Can't delete non-empty cohort {0} in course {1}".format(
name, course_id))
cohort.delete()