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Fix the order randomization behaviour of Randomized Content Block

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The Randomized Content Block XBlock only randomizes the selection of
the children blocks and has unpredictable randomization of
the order of the selected child blocks due to the usage of sets, which
are unordered, for storing the selected blocks. This becomes apparent
when all the available child blocks in a library are chosen for a
Randomized Content Block, to randomize just the order of the child
blocks and not just the selection of the blocks. The order of the
selected blocks ends up being similar for multiple learners.

This change modifies the XBlock to store the selected child blocks in
a list, instead of a set, after randomly shuffling them.

A new block structure transformer, ContentLibraryOrderTransformer has
been added to transform the order of the selected children XBlocks to
match the order of the selections made in the
ContentLibraryTransformer. This ensures that same correct randomized order
of blocks is also returned by the course blocks API.
This commit is contained in:
Guruprasad Lakshmi Narayanan
2020-08-06 12:58:19 +05:30
committed by Kyle McCormick
parent 8795bb8c82
commit 149ebfec58
6 changed files with 278 additions and 39 deletions
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45
common/lib/xmodule/xmodule/library_content_module.py
View File

@@ -160,37 +160,41 @@ class LibraryContentModule(LibraryContentFields, XModule, StudioEditableModule):
"""
rand = random.Random()
selected = set(tuple(k) for k in selected) # set of (block_type, block_id) tuples assigned to this student
selected_keys = set(tuple(k) for k in selected) # set of (block_type, block_id) tuples assigned to this student
# Determine which of our children we will show:
valid_block_keys = set([(c.block_type, c.block_id) for c in children])
valid_block_keys = set((c.block_type, c.block_id) for c in children)
# Remove any selected blocks that are no longer valid:
invalid_block_keys = (selected - valid_block_keys)
invalid_block_keys = (selected_keys - valid_block_keys)
if invalid_block_keys:
selected -= invalid_block_keys
selected_keys -= invalid_block_keys
# If max_count has been decreased, we may have to drop some previously selected blocks:
overlimit_block_keys = set()
if len(selected) > max_count:
num_to_remove = len(selected) - max_count
overlimit_block_keys = set(rand.sample(selected, num_to_remove))
selected -= overlimit_block_keys
if len(selected_keys) > max_count:
num_to_remove = len(selected_keys) - max_count
overlimit_block_keys = set(rand.sample(selected_keys, num_to_remove))
selected_keys -= overlimit_block_keys
# Do we have enough blocks now?
num_to_add = max_count - len(selected)
num_to_add = max_count - len(selected_keys)
added_block_keys = None
if num_to_add > 0:
# We need to select [more] blocks to display to this user:
pool = valid_block_keys - selected
pool = valid_block_keys - selected_keys
if mode == "random":
num_to_add = min(len(pool), num_to_add)
added_block_keys = set(rand.sample(pool, num_to_add))
# We now have the correct n random children to show for this user.
else:
raise NotImplementedError("Unsupported mode.")
selected |= added_block_keys
selected_keys |= added_block_keys
if any([invalid_block_keys, overlimit_block_keys, added_block_keys]):
selected = list(selected_keys)
random.shuffle(selected)
return {
'selected': selected,
@@ -270,19 +274,15 @@ class LibraryContentModule(LibraryContentFields, XModule, StudioEditableModule):
def selected_children(self):
"""
Returns a set() of block_ids indicating which of the possible children
Returns a list() of block_ids indicating which of the possible children
have been selected to display to the current user.
This reads and updates the "selected" field, which has user_state scope.
Note: self.selected and the return value contain block_ids. To get
Note: the return value (self.selected) contains block_ids. To get
actual BlockUsageLocators, it is necessary to use self.children,
because the block_ids alone do not specify the block type.
"""
if hasattr(self, "_selected_set"):
# Already done:
return self._selected_set # pylint: disable=access-member-before-definition
block_keys = self.make_selection(self.selected, self.children, self.max_count, "random") # pylint: disable=no-member
# Publish events for analytics purposes:
@@ -294,13 +294,12 @@ class LibraryContentModule(LibraryContentFields, XModule, StudioEditableModule):
self._publish_event,
)
# Save our selections to the user state, to ensure consistency:
selected = block_keys['selected']
self.selected = list(selected) # TODO: this doesn't save from the LMS "Progress" page.
# Cache the results
self._selected_set = selected # pylint: disable=attribute-defined-outside-init
if any(block_keys[changed] for changed in ('invalid', 'overlimit', 'added')):
# Save our selections to the user state, to ensure consistency:
selected = block_keys['selected']
self.selected = selected # TODO: this doesn't save from the LMS "Progress" page.
return selected
return self.selected
def _get_selected_child_blocks(self):
"""

19
common/lib/xmodule/xmodule/tests/test_library_content.py
View File

@@ -272,9 +272,8 @@ class LibraryContentModuleTestMixin(object):
Helper method that changes the max_count of self.lc_block, refreshes
children, and asserts that the number of selected children equals the count provided.
"""
# Clear the cache (only needed because we skip saving/re-loading the block) pylint: disable=protected-access
if hasattr(self.lc_block._xmodule, '_selected_set'):
del self.lc_block._xmodule._selected_set
# Construct the XModule for the descriptor, if not present already.
self.lc_block._xmodule # pylint: disable=pointless-statement,protected-access
self.lc_block.max_count = count
selected = self.lc_block.get_child_descriptors()
self.assertEqual(len(selected), count)
@@ -287,7 +286,7 @@ class TestLibraryContentModuleNoSearchIndex(LibraryContentModuleTestMixin, Libra
Tests for library container when no search index is available.
Tests fallback low-level CAPA problem introspection
"""
pass
pass # pylint:disable=unnecessary-pass
search_index_mock = Mock(spec=SearchEngine) # pylint: disable=invalid-name
@@ -365,8 +364,8 @@ class TestLibraryContentAnalytics(LibraryContentTest):
Check that a LibraryContentModule analytics event was published by self.lc_block.
"""
self.assertTrue(self.publisher.called)
self.assertTrue(len(self.publisher.call_args[0]), 3)
_, event_name, event_data = self.publisher.call_args[0]
self.assertTrue(len(self.publisher.call_args[0]), 3) # pylint:disable=unsubscriptable-object
_, event_name, event_data = self.publisher.call_args[0] # pylint:disable=unsubscriptable-object
self.assertEqual(event_name, "edx.librarycontentblock.content.{}".format(event_type))
self.assertEqual(event_data["location"], six.text_type(self.lc_block.location))
return event_data
@@ -397,8 +396,6 @@ class TestLibraryContentAnalytics(LibraryContentTest):
# Now increase max_count so that one more child will be added:
self.lc_block.max_count = 2
# Clear the cache (only needed because we skip saving/re-loading the block) pylint: disable=protected-access
del self.lc_block._xmodule._selected_set
children = self.lc_block.get_child_descriptors()
self.assertEqual(len(children), 2)
child, new_child = children if children[0].location == child.location else reversed(children)
@@ -478,8 +475,6 @@ class TestLibraryContentAnalytics(LibraryContentTest):
self.lc_block.get_child_descriptors() # This line is needed in the test environment or the change has no effect
self.publisher.reset_mock() # Clear the "assigned" event that was just published.
self.lc_block.max_count = 0
# Clear the cache (only needed because we skip saving/re-loading the block) pylint: disable=protected-access
del self.lc_block._xmodule._selected_set
# Check that the event says that one block was removed, leaving no blocks left:
children = self.lc_block.get_child_descriptors()
@@ -497,8 +492,6 @@ class TestLibraryContentAnalytics(LibraryContentTest):
# Start by assigning two blocks to the student:
self.lc_block.get_child_descriptors() # This line is needed in the test environment or the change has no effect
self.lc_block.max_count = 2
# Clear the cache (only needed because we skip saving/re-loading the block) pylint: disable=protected-access
del self.lc_block._xmodule._selected_set
initial_blocks_assigned = self.lc_block.get_child_descriptors()
self.assertEqual(len(initial_blocks_assigned), 2)
self.publisher.reset_mock() # Clear the "assigned" event that was just published.
@@ -512,8 +505,6 @@ class TestLibraryContentAnalytics(LibraryContentTest):
self.library.children = [keep_block_lib_usage_key]
self.store.update_item(self.library, self.user_id)
self.lc_block.refresh_children()
# Clear the cache (only needed because we skip saving/re-loading the block) pylint: disable=protected-access
del self.lc_block._xmodule._selected_set
# Check that the event says that one block was removed, leaving one block left:
children = self.lc_block.get_child_descriptors()

1
lms/djangoapps/course_blocks/api.py
View File

@@ -40,6 +40,7 @@ def get_course_block_access_transformers(user):
"""
course_block_access_transformers = [
library_content.ContentLibraryTransformer(),
library_content.ContentLibraryOrderTransformer(),
start_date.StartDateTransformer(),
ContentTypeGateTransformer(),
user_partitions.UserPartitionTransformer(),

68
lms/djangoapps/course_blocks/transformers/library_content.py
View File

@@ -4,6 +4,7 @@ Content Library Transformer.
import json
import logging
import six
from eventtracking import tracker
@@ -19,6 +20,8 @@ from xmodule.modulestore.django import modulestore
from ..utils import get_student_module_as_dict
logger = logging.getLogger(__name__)
class ContentLibraryTransformer(FilteringTransformerMixin, BlockStructureTransformer):
"""
@@ -101,7 +104,7 @@ class ContentLibraryTransformer(FilteringTransformerMixin, BlockStructureTransfo
# Save back any changes
if any(block_keys[changed] for changed in ('invalid', 'overlimit', 'added')):
state_dict['selected'] = list(selected)
state_dict['selected'] = selected
StudentModule.save_state(
student=usage_info.user,
course_id=usage_info.course_key,
@@ -177,3 +180,66 @@ class ContentLibraryTransformer(FilteringTransformerMixin, BlockStructureTransfo
format_block_keys,
publish_event,
)
class ContentLibraryOrderTransformer(BlockStructureTransformer):
"""
A transformer that manipulates the block structure by modifying the order of the
selected blocks within a library_content module to match the order of the selections
made by the ContentLibraryTransformer or the corresponding XBlock. So this transformer
requires the selections for the randomized content block to be already
made either by the ContentLibraryTransformer or the XBlock.
Staff users are *not* exempted from library content pathways.
"""
WRITE_VERSION = 1
READ_VERSION = 1
@classmethod
def name(cls):
"""
Unique identifier for the transformer's class;
same identifier used in setup.py
"""
return "library_content_randomize"
@classmethod
def collect(cls, block_structure):
"""
Collects any information that's necessary to execute this
transformer's transform method.
"""
# There is nothing to collect
pass # pylint:disable=unnecessary-pass
def transform(self, usage_info, block_structure):
"""
Transforms the order of the children of the randomized content block
to match the order of the selections made and stored in the XBlock 'selected' field.
"""
for block_key in block_structure:
if block_key.block_type != 'library_content':
continue
library_children = block_structure.get_children(block_key)
if library_children:
state_dict = get_student_module_as_dict(usage_info.user, usage_info.course_key, block_key)
current_children_blocks = set(block.block_id for block in library_children)
current_selected_blocks = set(item[1] for item in state_dict['selected'])
# As the selections should have already been made by the ContentLibraryTransformer,
# the current children of the library_content block should be the same as the stored
# selections. If they aren't, some other transformer that ran before this transformer
# has modified those blocks (for example, content gating may have affected this). So do not
# transform the order in that case.
if current_children_blocks != current_selected_blocks:
logger.info(
u'Mismatch between the children of %s in the stored state and the actual children for user %s. '
'Continuing without order transformation.',
str(block_key),
usage_info.user.username
)
else:
ordering_data = {block[1]: position for position, block in enumerate(state_dict['selected'])}
library_children.sort(key=lambda block, data=ordering_data: data[block.block_id])

183
lms/djangoapps/course_blocks/transformers/tests/test_library_content.py
View File

@@ -4,13 +4,14 @@ Tests for ContentLibraryTransformer.
from six.moves import range
import mock
from openedx.core.djangoapps.content.block_structure.api import clear_course_from_cache
from openedx.core.djangoapps.content.block_structure.transformers import BlockStructureTransformers
from student.tests.factories import CourseEnrollmentFactory
from ...api import get_course_blocks
from ..library_content import ContentLibraryTransformer
from ..library_content import ContentLibraryTransformer, ContentLibraryOrderTransformer
from .helpers import CourseStructureTestCase
@@ -167,3 +168,183 @@ class ContentLibraryTransformerTestCase(CourseStructureTestCase):
),
u"Expected 'selected' equality failed in iteration {}.".format(i)
)
class ContentLibraryOrderTransformerTestCase(CourseStructureTestCase):
"""
ContentLibraryOrderTransformer Test
"""
TRANSFORMER_CLASS_TO_TEST = ContentLibraryOrderTransformer
def setUp(self):
"""
Setup course structure and create user for content library order transformer test.
"""
super(ContentLibraryOrderTransformerTestCase, self).setUp()
self.course_hierarchy = self.get_course_hierarchy()
self.blocks = self.build_course(self.course_hierarchy)
self.course = self.blocks['course']
clear_course_from_cache(self.course.id)
# Enroll user in course.
CourseEnrollmentFactory.create(user=self.user, course_id=self.course.id, is_active=True)
def get_course_hierarchy(self):
"""
Get a course hierarchy to test with.
"""
return [{
'org': 'ContentLibraryTransformer',
'course': 'CL101F',
'run': 'test_run',
'#type': 'course',
'#ref': 'course',
'#children': [
{
'#type': 'chapter',
'#ref': 'chapter1',
'#children': [
{
'#type': 'sequential',
'#ref': 'lesson1',
'#children': [
{
'#type': 'vertical',
'#ref': 'vertical1',
'#children': [
{
'metadata': {'category': 'library_content'},
'#type': 'library_content',
'#ref': 'library_content1',
'#children': [
{
'metadata': {'display_name': "CL Vertical 2"},
'#type': 'vertical',
'#ref': 'vertical2',
'#children': [
{
'metadata': {'display_name': "HTML1"},
'#type': 'html',
'#ref': 'html1',
}
]
},
{
'metadata': {'display_name': "CL Vertical 3"},
'#type': 'vertical',
'#ref': 'vertical3',
'#children': [
{
'metadata': {'display_name': "HTML2"},
'#type': 'html',
'#ref': 'html2',
}
]
},
{
'metadata': {'display_name': "CL Vertical 4"},
'#type': 'vertical',
'#ref': 'vertical4',
'#children': [
{
'metadata': {'display_name': "HTML3"},
'#type': 'html',
'#ref': 'html3',
}
]
}
]
}
],
}
],
}
],
}
]
}]
@mock.patch('lms.djangoapps.course_blocks.transformers.library_content.get_student_module_as_dict')
def test_content_library_randomize(self, mocked):
"""
Test whether the order of the children blocks matches the order of the selected blocks when
course has content library section
"""
mocked.return_value = {
'selected': [
['vertical', 'vertical_vertical3'],
['vertical', 'vertical_vertical2'],
['vertical', 'vertical_vertical4'],
]
}
for i in range(5):
trans_block_structure = get_course_blocks(
self.user,
self.course.location,
self.transformers,
)
children = []
for block_key in trans_block_structure.topological_traversal():
if block_key.block_type == 'library_content':
children = trans_block_structure.get_children(block_key)
break
expected_children = ['vertical_vertical3', 'vertical_vertical2', 'vertical_vertical4']
self.assertEqual(
expected_children,
[child.block_id for child in children],
u"Expected 'selected' equality failed in iteration {}.".format(i)
)
@mock.patch('lms.djangoapps.course_blocks.transformers.library_content.get_student_module_as_dict')
def test_content_library_randomize_selected_blocks_mismatch(self, mocked):
"""
Test and verify that the ContentLibraryOrderTransformer's order transformation doesn't
happen when the current children blocks no longer match the selections made in the ContentLibraryTransformer
and stored in the database.
There are two types of block structure transformers - filtering and non-filtering. The filtering transformers
can only filter blocks from the block structure but cannot perform any other transformations. The
non-filtering transformers can transform the blocks in the block structure.
The ContentLibraryTransformer is a filtering transformer that selects the children blocks of the randomized
content blocks, saves the selection in the database and filters the blocks that are not selected.
The ContentLibraryOrderTransformer is a non-filtering transformer which transforms the order of the children
blocks of the randomized content block based on the order of the stored selection made by the
ContentLibraryTransformer.
The 'transform()' methods of all the filtering transformers are combined into a single transformation function
and run in a single block structure traversal. The non-filtering block structure transformers are run
after this.
When some filtering transformers like those for content visibility, gating etc. run after the
ContentLibraryTransformer and remove some/all of the selected children blocks before the
ContentLibraryTransformer runs, there will be a mismatch between the stored selected children blocks and
the current children blocks. When this happens, the ContentLibraryOrderTransformer shouldn't
transform the order.
"""
mocked.return_value = {
'selected': [
['vertical', 'vertical_vertical3'],
]
}
expected_children_without_hiding_or_gating = ['vertical_vertical3', ]
for _ in range(5):
trans_block_structure = get_course_blocks(
self.user,
self.course.location,
self.transformers,
)
children = []
for block_key in trans_block_structure.topological_traversal():
if block_key.block_type == 'library_content':
children = trans_block_structure.get_children(block_key)
break
self.assertNotEqual(
expected_children_without_hiding_or_gating,
[child.block_id for child in children],
)

1
setup.py
View File

@@ -53,6 +53,7 @@ setup(
],
"openedx.block_structure_transformer": [
"library_content = lms.djangoapps.course_blocks.transformers.library_content:ContentLibraryTransformer",
"library_content_randomize = lms.djangoapps.course_blocks.transformers.library_content:ContentLibraryOrderTransformer",
"split_test = lms.djangoapps.course_blocks.transformers.split_test:SplitTestTransformer",
"start_date = lms.djangoapps.course_blocks.transformers.start_date:StartDateTransformer",
"user_partitions = lms.djangoapps.course_blocks.transformers.user_partitions:UserPartitionTransformer",