[youdie006]

Check constraints get their DDL from QueryString.__str__ (via get_condition_str), which puts a string argument between single quotes without doubling the quotes inside it, and leaves a datetime.time unquoted because only datetime and date are handled:

class Band(Table):
    genre = Varchar()
    check_genre = Check(genre != "rock'n'roll")


class Shop(Table):
    opens = Time()
    check_opens = Check(opens >= datetime.time(9, 0))

ALTER TABLE "band" ADD CONSTRAINT check_genre CHECK ("genre" != 'rock'n'roll')
ALTER TABLE "shop" ADD CONSTRAINT check_opens CHECK ("opens" >= 09:00:00)

PostgreSQL's parser (checked with pglast / libpg_query) rejects both, so create_table() and the migration fail. With this change they become 'rock''n''roll' and '09:00:00', which parse. Strings without a quote and other types print as before; the only other visible change is that print(query) now shows '' for a quote inside a string.

Two tests are added to tests/query/test_querystring.py; they fail on master. The non-integration tests (sqlite) and scripts/lint.sh pass; the Postgres jobs need a server I didn't run.

Written with AI assistance (Claude); I have reviewed the change.

[dantownsend]

I've tested this locally, and it works well. Thanks for the fix 👍

I realised we might also have problems with timedelta too, and we could do with more test coverage for check constraints. That can be in a future PR though.