Add migration to populate site_values in SiteConfigurationHistory

[pwnage101]

Right now the ORM is very unhappy about the JSONField site_values
in SiteConfigurationHistory containing non-JSON (empty strings). We
cannot even write a data migration using the ORM to populate the field
because that causes a JSONDeserializationError. Therefore, we must
bypass the ORM and populate the values with raw SQL.

DENG-18

---

Testing in devstack:

DB state before migration:

mysql> select site_values from site_configuration_siteconfigurationhistory;
+-------------+
| site_values |
+-------------+
|             |
|             |
+-------------+
2 rows in set (0.00 sec)

Running the migration:

root@lms:/edx/app/edxapp/edx-platform# python manage.py cms migrate
...
Operations to perform:
  Apply all migrations: admin, announcements, api_admin, assessment, auth, block_structure, bookmarks, catalog, celery_utils, completion, consent, content_libraries, content_type_gating, contentserver, contentstore, contenttypes, cornerstone, course_action_state, course_creators, course_date_signals, course_duration_limits, course_groups, course_modes, course_overviews, courseware, coursewarehistoryextended, crawlers, credit, dark_lang, database_fixups, degreed, discounts, django_comment_common, django_notify, djcelery, edx_oauth2_provider, edx_proctoring, edx_when, edx_zoom, edxval, embargo, enterprise, entitlements, experiments, integrated_channel, lx_pathway_plugin, milestones, oauth2, oauth2_provider, oauth_dispatch, organizations, problem_builder, redirects, sap_success_factors, schedules, self_paced, sessions, site_configuration, sites, static_replace, student, submissions, survey, system_wide_roles, tagging, theming, track, user_api, user_authn, user_tasks, verified_track_content, verify_student, video_config, video_pipeline, waffle, waffle_utils, wiki, workflow, xapi, xblock_config, xblock_django
Running migrations:
  Applying site_configuration.0005_populate_siteconfig_history_site_values... OK

DB state after migration:

mysql> select site_values from site_configuration_siteconfigurationhistory;
+-------------+
| site_values |
+-------------+
| {}          |
| {}          |
+-------------+
2 rows in set (0.00 sec)

Running the reverse migration:

root@lms:/edx/app/edxapp/edx-platform# python manage.py cms migrate site_configuration 0004_add_site_values_field
...
Operations to perform:
  Target specific migration: 0004_add_site_values_field, from site_configuration
Running migrations:
  Rendering model states... DONE
  Unapplying site_configuration.0005_populate_siteconfig_history_site_values... OK

DB state after reverse migration:

mysql> select site_values from site_configuration_siteconfigurationhistory;
+-------------+
| site_values |
+-------------+
|             |
|             |
+-------------+
2 rows in set (0.00 sec)

[pwnage101]

I also just checked the PostgreSQL syntax and it should be valid, but I did not test: https://www.postgresql.org/docs/9.1/sql-update.html

[doctoryes]

I also just checked the PostgreSQL syntax and it should be valid, but I did not test: https://www.postgresql.org/docs/9.1/sql-update.html

Hmmm - I'm curious why the raw SQL needs to be PostgreSQL-complaint. Are there installations which use it? Does edx.org use it?

[doctoryes]

It's simple - 💟

[doctoryes]

Nit: Maybe use your Github handle? Or edX email address here? Or just remove this line? Because git knows all...

[pwnage101]

Hmmm - I'm curious why the raw SQL needs to be PostgreSQL-complaint. Are there installations which use it? Does edx.org use it?

edx.org does not, but I just figured since one reason we're doing this PR is for the open source community and who knows what they might be trying out.

[pwnage101]

jenkins run js

[pwnage101]

jenkins run bokchoy

[edx-status-bot]

Your PR has finished running tests. There were no failures.

[edx-pipeline-bot]

EdX Release Notice: This PR has been deployed to the staging environment in preparation for a release to production.

[edx-pipeline-bot]

EdX Release Notice: This PR may have caused e2e tests to fail on Stage. If you're a member of the edX org, please visit #e2e-troubleshooting on Slack to help diagnose the cause of these failures. Otherwise, it is the reviewer's responsibility. E2E tests have failed. https://gocd.tools.edx.org/go/tab/pipeline/history/deploy_to_stage

[edx-pipeline-bot]

EdX Release Notice: This PR has been deployed to the production environment.