154 lines
5.2 KiB
Python
154 lines
5.2 KiB
Python
import logging
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from django.contrib.auth.models import User
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from django.db import models
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log = logging.getLogger(__name__)
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class CourseUserGroup(models.Model):
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"""
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This model represents groups of users in a course. Groups may have different types,
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which may be treated specially. For example, a user can be in at most one cohort per
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course, and cohorts are used to split up the forums by group.
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"""
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class Meta:
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unique_together = (('name', 'course_id'), )
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name = models.CharField(max_length=255,
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help_text=("What is the name of this group? "
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"Must be unique within a course."))
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users = models.ManyToManyField(User, db_index=True, related_name='course_groups',
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help_text="Who is in this group?")
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# Note: groups associated with particular runs of a course. E.g. Fall 2012 and Spring
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# 2013 versions of 6.00x will have separate groups.
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course_id = models.CharField(max_length=255, db_index=True,
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help_text="Which course is this group associated with?")
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# For now, only have group type 'cohort', but adding a type field to support
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# things like 'question_discussion', 'friends', 'off-line-class', etc
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COHORT = 'cohort'
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GROUP_TYPE_CHOICES = ((COHORT, 'Cohort'),)
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group_type = models.CharField(max_length=20, choices=GROUP_TYPE_CHOICES)
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def get_cohort(user, course_id):
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"""
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Given a django User and a course_id, return the user's cohort. In classes with
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auto-cohorting, put the user in a cohort if they aren't in one already.
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Arguments:
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user: a Django User object.
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course_id: string in the format 'org/course/run'
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Returns:
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A CourseUserGroup object if the User has a cohort, or None.
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"""
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try:
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group = CourseUserGroup.objects.get(course_id=course_id,
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group_type=CourseUserGroup.COHORT,
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users__id=user.id)
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except CourseUserGroup.DoesNotExist:
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group = None
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if group:
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return group
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# TODO: add auto-cohorting logic here
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return None
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def get_course_cohorts(course_id):
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"""
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Get a list of all the cohorts in the given course.
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Arguments:
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course_id: string in the format 'org/course/run'
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Returns:
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A list of CourseUserGroup objects. Empty if there are no cohorts.
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"""
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return list(CourseUserGroup.objects.filter(course_id=course_id,
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group_type=CourseUserGroup.COHORT))
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### Helpers for cohor management views
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def get_cohort_by_name(course_id, name):
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"""
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Return the CourseUserGroup object for the given cohort. Raises DoesNotExist
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it isn't present.
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"""
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return CourseUserGroup.objects.get(course_id=course_id,
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group_type=CourseUserGroup.COHORT,
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name=name)
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def get_cohort_by_id(course_id, cohort_id):
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"""
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Return the CourseUserGroup object for the given cohort. Raises DoesNotExist
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it isn't present. Uses the course_id for extra validation...
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"""
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return CourseUserGroup.objects.get(course_id=course_id,
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group_type=CourseUserGroup.COHORT,
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id=cohort_id)
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def add_cohort(course_id, name):
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"""
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Add a cohort to a course. Raises ValueError if a cohort of the same name already
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exists.
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"""
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log.debug("Adding cohort %s to %s", name, course_id)
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if CourseUserGroup.objects.filter(course_id=course_id,
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group_type=CourseUserGroup.COHORT,
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name=name).exists():
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raise ValueError("Can't create two cohorts with the same name")
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return CourseUserGroup.objects.create(course_id=course_id,
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group_type=CourseUserGroup.COHORT,
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name=name)
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def add_user_to_cohort(cohort, username_or_email):
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"""
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Look up the given user, and if successful, add them to the specified cohort.
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Arguments:
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cohort: CourseUserGroup
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username_or_email: string. Treated as email if has '@'
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Returns:
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User object.
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Raises:
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User.DoesNotExist if can't find user.
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ValueError if user already present.
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"""
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if '@' in username_or_email:
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user = User.objects.get(email=username_or_email)
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else:
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user = User.objects.get(username=username_or_email)
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if cohort.users.filter(id=user.id).exists():
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raise ValueError("User {0} already present".format(user.username))
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cohort.users.add(user)
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return user
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def get_course_cohort_names(course_id):
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"""
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Return a list of the cohort names in a course.
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"""
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return [c.name for c in get_course_cohorts(course_id)]
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def delete_empty_cohort(course_id, name):
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"""
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Remove an empty cohort. Raise ValueError if cohort is not empty.
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"""
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cohort = get_cohort_by_name(course_id, name)
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if cohort.users.exists():
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raise ValueError(
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"Can't delete non-empty cohort {0} in course {1}".format(
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name, course_id))
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cohort.delete()
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