78 lines
2.8 KiB
Python
78 lines
2.8 KiB
Python
"""
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Start Date Transformer implementation.
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"""
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from openedx.core.lib.block_structure.transformer import BlockStructureTransformer, FilteringTransformerMixin
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from lms.djangoapps.courseware.access_utils import check_start_date
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from xmodule.course_metadata_utils import DEFAULT_START_DATE
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from .utils import collect_merged_date_field
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class StartDateTransformer(FilteringTransformerMixin, BlockStructureTransformer):
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"""
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A transformer that enforces the 'start' and 'days_early_for_beta'
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fields on blocks by removing blocks from the block structure for
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which the user does not have access. The 'start' field on a
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block is percolated down to its descendants, so that all blocks
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enforce the 'start' field from their ancestors. The assumed
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'start' value for a block is then the maximum of its parent and its
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own.
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For a block with multiple parents, the assumed parent start date
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value is a computed minimum of the start dates of all its parents.
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So as long as one parent chain allows access, the block has access.
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Staff users are exempted from visibility rules.
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"""
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VERSION = 1
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MERGED_START_DATE = 'merged_start_date'
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@classmethod
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def name(cls):
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"""
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Unique identifier for the transformer's class;
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same identifier used in setup.py.
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"""
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return "start_date"
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@classmethod
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def _get_merged_start_date(cls, block_structure, block_key):
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"""
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Returns the merged value for the start date for the block with
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the given block_key in the given block_structure.
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"""
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return block_structure.get_transformer_block_field(
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block_key, cls, cls.MERGED_START_DATE, False
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)
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@classmethod
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def collect(cls, block_structure):
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"""
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Collects any information that's necessary to execute this
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transformer's transform method.
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"""
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block_structure.request_xblock_fields('days_early_for_beta')
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collect_merged_date_field(
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block_structure,
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transformer=cls,
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xblock_field_name='start',
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merged_field_name=cls.MERGED_START_DATE,
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default_date=DEFAULT_START_DATE,
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func_merge_parents=min,
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func_merge_ancestors=max,
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)
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def transform_block_filters(self, usage_info, block_structure):
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# Users with staff access bypass the Start Date check.
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if usage_info.has_staff_access:
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return [block_structure.create_universal_filter()]
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removal_condition = lambda block_key: not check_start_date(
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usage_info.user,
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block_structure.get_xblock_field(block_key, 'days_early_for_beta'),
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self._get_merged_start_date(block_structure, block_key),
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usage_info.course_key,
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)
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return [block_structure.create_removal_filter(removal_condition)]
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