Files
edx-platform/lms/djangoapps/course_blocks/api.py
2015-11-05 14:41:40 -05:00

98 lines
3.7 KiB
Python

"""
API entry point to the course_blocks app with top-level
get_course_blocks and clear_course_from_cache functions.
"""
from django.core.cache import cache
from openedx.core.lib.block_cache.block_cache import get_blocks, clear_block_cache
from xmodule.modulestore.django import modulestore
from .transformers import (
library_content,
start_date,
user_partitions,
visibility,
)
from .usage_info import CourseUsageInfo
# Default list of transformers for manipulating course block structures
# based on the user's access to the course blocks.
COURSE_BLOCK_ACCESS_TRANSFORMERS = [
library_content.ContentLibraryTransformer(),
start_date.StartDateTransformer(),
user_partitions.UserPartitionTransformer(),
visibility.VisibilityTransformer(),
]
def get_course_blocks(
user,
root_block_usage_key,
transformers=None
):
"""
A higher order function implemented on top of the
block_cache.get_blocks function returning a transformed block
structure for the given user starting at root_block_usage_key.
Note: The current implementation requires the root_block_usage_key
to be the root block of its corresponding course. However, this
is a short-term limitation, which will be addressed in a coming
ticket (https://openedx.atlassian.net/browse/MA-1604). Once that
ticket is implemented, callers will be able to get course blocks
starting at any arbitrary location within a block structure.
Arguments:
user (django.contrib.auth.models.User) - User object for
which the block structure is to be transformed.
root_block_usage_key (UsageKey) - The usage_key for the root
of the block structure that is being accessed.
transformers ([BlockStructureTransformer]) - The list of
transformers whose transform methods are to be called.
If None, COURSE_BLOCK_ACCESS_TRANSFORMERS is used.
Returns:
BlockStructureBlockData - A transformed block structure,
starting at root_block_usage_key, that has undergone the
transform methods for the given user and the course
associated with the block structure. If using the default
transformers, the transformed block structure will be
exactly equivalent to the blocks that the given user has
access.
"""
store = modulestore()
if root_block_usage_key != store.make_course_usage_key(root_block_usage_key.course_key):
# Enforce this check for now until MA-1604 is implemented.
# Otherwise, callers will get incorrect block data after a
# new version of the course is published, since
# clear_course_from_cache only clears the cached block
# structures starting at the root block of the course.
raise NotImplementedError
return get_blocks(
cache,
store,
CourseUsageInfo(root_block_usage_key.course_key, user),
root_block_usage_key,
COURSE_BLOCK_ACCESS_TRANSFORMERS if transformers is None else transformers,
)
def clear_course_from_cache(course_key):
"""
A higher order function implemented on top of the
block_cache.clear_block_cache function that clears the block
structure from the cache for the block structure starting at the
root block of the course for the given course_key.
Note: See Note in get_course_blocks. Even after MA-1604 is
implemented, this implementation should still be valid since the
entire block structure of the course is cached, even though
arbitrary access to an intermediate block will be supported.
"""
course_usage_key = modulestore().make_course_usage_key(course_key)
return clear_block_cache(cache, course_usage_key)