piccolo

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Ran into an issue where I was doing an incorrect and clause, as follows:

 def following(self, user: "User") -> bool:
        """
        Return whether the user is following the queue
        """
        t = TQueueFollow\
            .exists()\
            .where(
                TQueueFollow.queue == self.id
                and TQueueFollow.user == user.id
            ).run_sync()
        assert isinstance(t, bool)
        return t

The mistake I made is that I used and instead of & to build the clause. If possible, some additional type constraints should be added so that tools such as mypy will detect this error.

Yeah, interesting.

We have a check here:

https://github.com/piccolo-orm/piccolo/blob/248c209cb3de26181aac907a68552f525dc182f2/piccolo/query/mixins.py#L171-L179

But the intention was to catch errors like MyTable.select().where(MyTable.some_column is 1).

In that example, MyTable.some_column is 1 returns a boolean, so we catch that.

But in your example, it uses and. So:

TQueueFollow.queue == self.id and TQueueFollow.user == user.id

Is evaluated to:

TQueueFollow.user == user.id

Which is a valid statement for where.

So it's actually really tricky! We can't override and in Python either (to my knowledge).