On 4/20/15 8:09 AM, Guido Winkelmann wrote:
Hi,
Have there been any non-backwards-compatible changes in SQLAlchemy 1.0
compared to 0.9.9?
We are seeing a lot of sudden breakage in our unit tests when
switching to SQLAlchemy 1.0 from 0.9.9. Tests that worked fine before
suddenly fail across the board.
Here's a an example of a test build that suddenly failed on 1.0:
https://travis-ci.org/pyfarm/pyfarm-master/builds/58860924
If you compare the builds on sqlite with those MySQL/PostgreSQL, you
will see there are two different, seemingly unrelated things going wrong:
On sqlite, drop_all() seems to fail to get the order of table drops
right, and consequently runs into a referential integrity error.
On MySQL/PostgreSQL, this line fails:
association = TaskTaskLogAssociation.query.filter_by(task=task,
log=task_log, attempt=attempt).first()
In this context, "log" is a relationship in the
model TaskTaskLogAssociation to model TaskLog. "task_log" is an object
of type TaskLog, but one that has never been written to the database
and has no set id. That leads to this error message in the logs:
nose.proxy.ProgrammingError: (psycopg2.ProgrammingError) function
symbol(unknown) does not exist
LINE 3: ...72015052936_task_log_associations.attempt = 1 AND symbol('NE...
^
HINT: No function matches the given name and argument types. You
might need to add explicit type casts.
[SQL: 'SELECT test29172015052936_task_log_associations.task_log_id AS
test29172015052936_task_log_associations_task_log_id,
test29172015052936_task_log_associations.task_id AS
test29172015052936_task_log_associations_task_id,
test29172015052936_task_log_associations.attempt AS
test29172015052936_task_log_associations_attempt,
test29172015052936_task_log_associations.state AS
test29172015052936_task_log_associations_state \nFROM
test29172015052936_task_log_associations \nWHERE
test29172015052936_task_log_associations.attempt = %(attempt_1)s AND
%(param_1)s = test29172015052936_task_log_associations.task_log_id AND
%(param_2)s = test29172015052936_task_log_associations.task_id \n
LIMIT %(param_3)s'] [parameters: {'param_1': symbol('NEVER_SET'),
'attempt_1': 1, 'param_2': 1, 'param_3': 1}]
Apparently, sqlalchemy will use "symbol('NEVER_SET')" where the id of
the model used for filtering should be.
It may be a bit questionable to filter by a model that doesn't even
exist in the database, but, again, this used to work fine in 0.9.9.
This is odd. What was "working fine" in 0.9.9 doing exactly? Was it
coming out with "NULL =
test29172015052936_task_log_associations.task_log_id" ? Looking in
0.9, there is no logic in this case to convert the "=" to "IS" in this
case as the parameter from the object is not evaluated til after the
query is generated. This query will *always* return False, because
NULL cannot be compared with "=".
I guess that's whats desired here, that the query returns nothing, but
this is a lot like the idea of "x IN ()", e.g. it's useless to emit this
query, and it relies upon kind of a weird quirk of SQL. I almost wonder
if this should emit a warning. Because if we do eventually make it so
that IS NULL comes out, the results can change for more complex
relationships that explicitly want to compare some columns to NULL.
Regards,
Guido W.
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