On Thu, Oct 22, 2020 at 08:31:34PM +1100, Steven D'Aprano wrote:
cursor.execute(f"INSERT INTO {table} VALUES (1, '{}');")
SyntaxError: f-string: empty expression not allowed
Escape the braces by doubling them:
f"INSERT INTO {table} VALUES (1, '{{}}');"
Thank you for (ugly) workaorund.
The problem here is with the f-string, not the call to cursor.execute.
We can simplify the example to this:
f'{}'
and avoid the distraction of JSON, SQL, databases, etc.
Technically we can, but the context give us a useful example.
Strings like f"Use braces ({}) for {something}."
are also a useful example.
Empty expression in f-string should
* (silently) expand as '{}' (opening and closing braces),
* generate a (compile time) warning if requested, e.g. with -W.
We could do that, but this is more likely to just hide bugs in the
f-string than be useful.
Thank you, that would be great and useful.
Users will be warned before potentially bug two times:
1) They will see the {} in output (which should be tested).
2) By the compiler when they ask for (-W), which is a better behaviour than
forced carefulness.
--
BR, H.
_______________________________________________
Python-ideas mailing list -- python-ideas@python.org
To unsubscribe send an email to python-ideas-le...@python.org
https://mail.python.org/mailman3/lists/python-ideas.python.org/
Message archived at
https://mail.python.org/archives/list/python-ideas@python.org/message/2B5KEM34SUO3TXDMMZE6A332L3SKVLEF/
Code of Conduct: http://python.org/psf/codeofconduct/
