This will make django automatically remove them when we run
squashmigrations. There are still some RunSQL statements which
we will have to take care of manually.
Previously, alert words were case-insensitive in practice, by which I
mean the Markdown logic had always been case-insensitive; but the data
model was not, so you could create "duplicate" alert words with the
same words in different cases. We fix this inconsistency by making
the database model case-insensitive.
I'd prefer to be using the Postgres `citext` extension to have
postgres take care of case-insensitive logic for us, but that requires
installing a postgres extension as root on the postgres server, which
is a pain and perhaps not worth the effort to arrange given that we
can achieve our goals with transaction when adding alert words.
We take advantage of the migrate_alert_words migration we're already
doing for all users to effect this transition.
Fixes#12563.
Previously, alert words were a JSON list of strings stored in a
TextField on user_profile. That hacky model reflected the fact that
they were an early prototype feature.
This commit migrates from that to a separate table, 'AlertWord'. The
new AlertWord has user_profile, word, id and realm(denormalization so
we can provide a nice index for fetching all the alert words in a
realm).
This transition requires moving the logic for flushing the Alert Words
caches to their own independent feature.
Note that this commit should not be cherry-picked without the
following commit, which fixes case-sensitivity issues with Alert Words.
Anders Kaseorg
Aman Agrawal
Tim Abbott
Abhishek-Balaji