Error when recording SQL queries that are byte-strings

[ahardjasa]

When a byte-string SQL query is run, e.g. those produced by psycopg2.execute_values, I get the error TypeError: startswith first arg must be bytes or a tuple of bytes, not str.

This seems to be a result of line 142 in django-debug-toolbar/debug_toolbar/panels/sql/tracking.py: 'is_select': sql.lower().strip().startswith('select')
since 'select' is unicode.

Flask-debugtoolbar addressed this with prefix = b'select' if isinstance(statement, bytes) else 'select' - would that work in this case?

[matthiask]

The DB API 2.0 PEP (https://www.python.org/dev/peps/pep-0249/) does not mandate a type for the SQL operation -- whether it's bytes or str isn't defined (which isn't surprising at all since the PEP was added at least 17 years ago).

Still, I'm a bit reluctant because I fear breakage throughout; is this really all that's required to support byte string queries? Should we even support byte string queries at all?

[aaugustin]

I'm OK with that change.

[matthiask]

Great. @ahardjasa do you want to submit a pull request?

[thaxy]

Same problem for Django raw SQL queries such as:

with connection.cursor() as cursor:
            cursor.execute(
                sql.SQL(
                    '''
                    SELECT json_build_object(
                        'data', array_agg(r)
                    )
                    FROM (
                        SELECT
                        a,
                        {}
                        FROM b
                        WHERE c=%s
                        ORDER BY a DESC
                        LIMIT %s
                    ) r
                    '''
                ).format(var),
                [x, 5]
            )
            result = cursor.fetchall()

[bschollnick]

This appears to be a problem for me as well. I'm not sure if this should be broken off into a different issue ticket?

I'm storing binary image thumbnails, and it works fine when I am not running django debug toolbar, but as soon as I enable DDT, a bit of chaos occurs.

With it enabled, Django can not store, read, or manipulate the binary fields. Everything else works fine, but the binary fields do not work.

[Caiofcas]

Is this still a problem? Looking around I found this test (in tests/panels/test_sql.py) and it seems to catch this use case:

def test_non_ascii_query(self):
        ...
        # non-ASCII bytes parameters
        list(Binary.objects.filter(field__in=["café".encode()]))
        self.assertEqual(len(self.panel._queries), 3)
        ...

[matthiask]

@Caiofcas Thank you! If I'm reading this issue correctly it is about the whole SQL string being bytes which is different from the test where (only) a parameter is bytes.

[Lucidiot]

I just got this with the latest version, 4.1.0. This line in psycopg2.extras.execute_values causes it to execute a query of type bytes.

utting this in a view alone will raise the issue when the toolbar is active:

from django.db import connection

with connection.cursor() as cursor:
    cursor.execute(b'SELECT 1')

[matthiask]

@Lucidiot It seems nobody is actively working on this right now. Does the proposed fix in the initial report make everything work as it should? It would be very helpful if you could check this and maybe submit a pull request with a small test case. Thanks in advance!

[living180]

@Lucidiot I could also potentially take a look in the next couple of days if you don't have time to get a PR together.

[Lucidiot]

I found that I was hitting an error in another place, before the code originally mentioned in this issue could even be called, so I fixed that instead and now the query seems to always be a string by the time it reaches the is_select of the initial report.