#96 "where x in %s" failes with single-element tuple

[Larry Hastings]

This:
db.execute("delete from table where index in %s", ((1, 2, 3),) )
works fine.

But this:
db.execute("delete from table where index in %s", ((1,),) )
fails with a syntax error.

It's because PyPgSQL renders the arguments into the command, so the command fed into PostgreSQL becomes
delete from table where index in (1,);
and PostgreSQL's parser doesn't like a one-element tuple like that.

I suspect the fix is: notice when rendering a one-element tuple, and somehow remove or prevent the comma.

[Andrew McNamara]

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You might want to check that you're using an up-to-date version of pyPgSQL - I seem to remember this being fixed in 2.4. I use IN queries extensively in my apps, and I haven't had a complaint about this problem for some time.

[Larry Hastings]

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I'm using 2.5.1, and I definitely saw the problem. Where in the code does it handle this case?

[Andrew McNamara]

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In PgSQL.py, the function _quote() is responsible for this. For example:

>>> from pyPgSQL import PgSQL
>>> PgSQL._quote((1,))
'(1)'