Consider using enable_callback_tracebacks(True)

[simonw]

From https://docs.python.org/3/library/sqlite3.html#sqlite3.enable_callback_tracebacks

sqlite3.``enable_callback_tracebacks(flag)¶

By default you will not get any tracebacks in user-defined functions, aggregates, converters, authorizer callbacks etc. If you want to debug them, you can call this function with flag set to True. Afterwards, you will get tracebacks from callbacks on sys.stderr. Use False to disable the feature again.

Maybe turn this on for all of Datasette? Are there any disadvantages to doing that?

[simonw]

peter-wangxu/persist-queue#74 warns that this might not work with PyPy.

I could solve that with:

if hasattr(sqlite3, "enable_callback_tracebacks"):
    sqlite3.enable_callback_tracebacks(True)

[simonw]

I've been trying to figure out why this is an optional setting that defaults to off.

I think it's because it writes directly to stderr, so the maintainers of sqlite3 reasonably decided that people should be able to opt in to that rather than having weird stuff show up on stderr that they weren't expecting.

[simonw]

Here's the commit (from 15 years ago) where enable_callback_tracebacks was first added: ghaering/pysqlite@1e8bd36

• Exceptions in callbacks lead to the query being aborted now instead of silently leading to generating values.
• Exceptions in callbacks can be echoed to stderr if you call the module level function enable_callback_tracebacks: enable_callback_tracebacks(1).

[simonw]

I'm going to turn this on. If people complain about it I can turn it off again (or make it a configuration setting).

[simonw]

Here's what that looks like:

Traceback (most recent call last):
  File "/Users/simon/Dropbox/Development/datasette/plugins/sql_error.py", line 5, in oh_no_error
    return 100 / 0
ZeroDivisionError: division by zero
ERROR: conn=<sqlite3.Connection object at 0x10bce0030>, sql = 'select oh_no_error()', params = {}: user-defined function raised exception
INFO:     127.0.0.1:54066 - "GET /data?sql=select+oh_no_error%28%29 HTTP/1.1" 400 Bad Request