create data migration to populate FBEEnrollmentExclusion table

common/djangoapps/student/migrations/0025_auto_20191101_1846.py

+# -*- coding: utf-8 -*-
+# Generated by Django 1.11.25 on 2019-11-01 18:46
+from __future__ import unicode_literals
+
+from django.db import migrations
+
+from experiments.models import ExperimentData
+from openedx.features.course_duration_limits.config import EXPERIMENT_DATA_HOLDBACK_KEY, EXPERIMENT_ID
+from student.models import CourseEnrollment, FBEEnrollmentExclusion
+
+
+def populate_fbeenrollmentexclusion(apps, schema_editor):
+    holdback_entries = ExperimentData.objects.filter(
+        experiment_id=EXPERIMENT_ID,
+        key=EXPERIMENT_DATA_HOLDBACK_KEY,
+        value='True'
+    )
+    for holdback_entry in holdback_entries:
+        enrollments = [FBEEnrollmentExclusion(enrollment=enrollment)
+                       for enrollment in CourseEnrollment.objects.filter(user=holdback_entry.user)]
+        if enrollments:
+            FBEEnrollmentExclusion.objects.bulk_create(enrollments)
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('student', '0024_fbeenrollmentexclusion'),
+    ]
+
+    operations = [
+        migrations.RunPython(populate_fbeenrollmentexclusion, reverse_code=migrations.RunPython.noop),
+    ]