From 149ebfec586c8f5041ef385bb9b188c7e00feddb Mon Sep 17 00:00:00 2001 From: Guruprasad Lakshmi Narayanan Date: Thu, 6 Aug 2020 12:58:19 +0530 Subject: [PATCH] Fix the order randomization behaviour of Randomized Content Block 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. --- .../xmodule/xmodule/library_content_module.py | 45 +++-- .../xmodule/tests/test_library_content.py | 19 +- lms/djangoapps/course_blocks/api.py | 1 + .../transformers/library_content.py | 68 ++++++- .../tests/test_library_content.py | 183 +++++++++++++++++- setup.py | 1 + 6 files changed, 278 insertions(+), 39 deletions(-) diff --git a/common/lib/xmodule/xmodule/library_content_module.py b/common/lib/xmodule/xmodule/library_content_module.py index 9c204a0c9b..fd58beaeea 100644 --- a/common/lib/xmodule/xmodule/library_content_module.py +++ b/common/lib/xmodule/xmodule/library_content_module.py @@ -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children]) + valid_block_keys = set((c.block_type, c.block_id) for c in children) # Remove any selected blocks that are no longer valid: - invalid_block_keys = (selected - valid_block_keys) + invalid_block_keys = (selected_keys - valid_block_keys) if invalid_block_keys: - selected -=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): """ diff --git a/common/lib/xmodule/xmodule/tests/test_library_content.py b/common/lib/xmodule/xmodule/tests/test_library_content.py index d885d9129f..888dd4cfad 100644 --- a/common/lib/xmodule/xmodule/tests/test_library_content.py +++ b/common/lib/xmodule/xmodule/tests/test_library_content.py @@ -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() diff --git a/lms/djangoapps/course_blocks/api.py b/lms/djangoapps/course_blocks/api.py index 569eeb947e..a8eb5bf0e5 100644 --- a/lms/djangoapps/course_blocks/api.py +++ b/lms/djangoapps/course_blocks/api.py @@ -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(), diff --git a/lms/djangoapps/course_blocks/transformers/library_content.py b/lms/djangoapps/course_blocks/transformers/library_content.py index 004177d602..59e0d5f640 100644 --- a/lms/djangoapps/course_blocks/transformers/library_content.py +++ b/lms/djangoapps/course_blocks/transformers/library_content.py @@ -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]) diff --git a/lms/djangoapps/course_blocks/transformers/tests/test_library_content.py b/lms/djangoapps/course_blocks/transformers/tests/test_library_content.py index ecf6eac39a..bb3cbad872 100644 --- a/lms/djangoapps/course_blocks/transformers/tests/test_library_content.py +++ b/lms/djangoapps/course_blocks/transformers/tests/test_library_content.py @@ -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], + ) diff --git a/setup.py b/setup.py index ada332a49d..f21177e1b0 100644 --- a/setup.py +++ b/setup.py @@ -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",