ff0c1d57da
When a student submits a problem answer, the state is stored in a StudentModule record containing answer, score, correctness, etc. The record, though, is updated in multiple steps within the single request (first the grade is updated, then the state is updated separately). Each partial save would trigger a separate StudentModuleHistory record to be stored resulting in duplicate and inaccurate historical records. This solution uses the RequestCache to track within a request thread which StudentModules are updated and a single corresponding StudentModuleHistory id. If multiple update actions occur within the request cycle, then modify the history record that was already generated to ensure that each submission only results in one StudentModuleHistory record. This issue and its solution were discussed in: https://discuss.openedx.org/t/extra-history-record-stored-on-each-problem-submission/8081
65 lines
2.5 KiB
Python
65 lines
2.5 KiB
Python
"""
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WE'RE USING MIGRATIONS!
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If you make changes to this model, be sure to create an appropriate migration
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file and check it in at the same time as your model changes. To do that,
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1. Go to the edx-platform dir
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2. ./manage.py schemamigration courseware --auto description_of_your_change
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3. Add the migration file created in edx-platform/lms/djangoapps/coursewarehistoryextended/migrations/
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ASSUMPTIONS: modules have unique IDs, even across different module_types
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"""
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from django.db import models
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from django.db.models.signals import post_delete, post_save
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from django.dispatch import receiver
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from lms.djangoapps.courseware.models import BaseStudentModuleHistory, StudentModule
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from lms.djangoapps.courseware.fields import UnsignedBigIntAutoField
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class StudentModuleHistoryExtended(BaseStudentModuleHistory):
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"""Keeps a complete history of state changes for a given XModule for a given
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Student. Right now, we restrict this to problems so that the table doesn't
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explode in size.
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This new extended CSMH has a larger primary key that won't run out of space
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so quickly."""
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class Meta:
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app_label = 'coursewarehistoryextended'
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get_latest_by = "created"
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index_together = ['student_module']
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id = UnsignedBigIntAutoField(primary_key=True) # pylint: disable=invalid-name
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student_module = models.ForeignKey(StudentModule, db_index=True, db_constraint=False, on_delete=models.DO_NOTHING)
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@receiver(post_save, sender=StudentModule)
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def save_history(sender, instance, **kwargs): # pylint: disable=no-self-argument, unused-argument
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"""
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Checks the instance's module_type, and creates & saves a
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StudentModuleHistoryExtended entry if the module_type is one that
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we save.
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"""
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BaseStudentModuleHistory.save_history_entry(
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instance,
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StudentModuleHistoryExtended,
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"lms.djangoapps.coursewarehistoryextended.models.student_module_history_extended_map"
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)
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@receiver(post_delete, sender=StudentModule)
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def delete_history(sender, instance, **kwargs): # pylint: disable=no-self-argument, unused-argument
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"""
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Django can't cascade delete across databases, so we tell it at the model level to
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on_delete=DO_NOTHING and then listen for post_delete so we can clean up the CSMHE rows.
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"""
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StudentModuleHistoryExtended.objects.filter(student_module=instance).all().delete()
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def __str__(self):
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return str(repr(self))
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