Add migration to generate probleminstances

Author: matijapretnar

web/courses/migrations/0005_generate_probleminstances.py

@@ -0,0 +1,38 @@
+# Generated by Django 4.1.2 on 2023-02-19 11:02
+
+from django.db import migrations
+from django.db import models
+
+
+def generate_probleminstances(apps, schema_editor):
+    # We can't import the Person model directly as it may be a newer
+    # version than this migration expects. We use the historical version.
+    Problem = apps.get_model('problems', 'Problem')
+    ProblemInstance = apps.get_model('courses', 'ProblemInstance')
+    problems = Problem.objects.values_list('id', 'problem_set_id', 'visible', '_order')
+    instances = [ProblemInstance(
+            problem_id=id,
+            problem_set_id=problem_set_id,
+            visible=visible,
+            _order=_order
+        ) for id, problem_set_id, visible, _order in problems
+    ]
+    instances = ProblemInstance.objects.bulk_create(instances, batch_size=1000)
+    problem_id_to_instance_id = {instance.problem_id: instance.id for instance in instances}
+    for class_name in ["Attempt", "HistoricalAttempt"]:
+        Attempt = apps.get_model('attempts', class_name)
+        attempts = Attempt.objects.annotate(problem_id=models.F('part__problem_id'))
+        for attempt in attempts:
+            attempt.problem_instance_id = problem_id_to_instance_id[attempt.problem_id]
+        Attempt.objects.bulk_update(attempts, ['problem_instance_id'], batch_size=1000)
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ("courses", "0004_probleminstance"),
+        ("attempts", "0004_attempt_problem_instance_and_more"),
+    ]
+
+    operations = [
+        migrations.RunPython(generate_probleminstances),
+    ]