6 ms·

I'm not familiar with this library, how does `text("(now())")` evaluate and why there are extra parentheses? And should that be a lambda expression as well, so

I'm not familiar with this library, how does `text("(now())")` evaluate and why there are extra parentheses? And should that be a lambda expression as well, so that `create_date` isn't just the timestamp when the python process was started?

yeputons 2y ago
I suspect it's either just an SQL expression sent to the DB, or it's `eval`ed in Python.
openmajestic 2y ago
IIRC, the difference is server_default vs default. One is generated DB-side, the other in the Python code. Might be wrong on that, but that's my recollection
oxidant 2y ago
My guess is that "now()" is the DB function that returns the current timestamp.
jhardy54 2y ago
I’ll note that the bug is in the `id` column, but the `created_date` is likely passing the string “now()” to invoke SQL’s NOW(), deferring the timestamp creation to the database.
crote 2y ago
I'm not familiar with the library either, but that seems to be a SQL expression executed on the database server. It's basically a copy-paste from the official documentation[0]. So no, not a lambda expression, because it's not computed in Python. As to the extra parentheses: I bet that's a force-of-habit thing to prevent potential issues. For example, it seems Sqlite requires them for exactly this kind of default definition[1]. It could also read to nasty bugs when the lack of parentheses in the resulting SQL could result in a different parse than expected[2]. Adding them just-to-be-safe isn't the worst thing to do. [0]: https://docs.sqlalchemy.org/en/13/core/metadata.html https://docs.sqlalchemy.org/en/13/core/metadata.html [1]: https://github.com/sqlalchemy/sqlalchemy/issues/4474 https://github.com/sqlalchemy/sqlalchemy/issues/4474 [2]: https://github.com/sqlalchemy/sqlalchemy/issues/5344 https://github.com/sqlalchemy/sqlalchemy/issues/5344
- nikonyrh 2y ago
  Aah that makes sense, thanks!

yeputons 2y ago

I suspect it's either just an SQL expression sent to the DB, or it's `eval`ed in Python.

openmajestic 2y ago

IIRC, the difference is server_default vs default. One is generated DB-side, the other in the Python code. Might be wrong on that, but that's my recollection

oxidant 2y ago

My guess is that "now()" is the DB function that returns the current timestamp.

jhardy54 2y ago

I’ll note that the bug is in the `id` column, but the `created_date` is likely passing the string “now()” to invoke SQL’s NOW(), deferring the timestamp creation to the database.

crote 2y ago

I'm not familiar with the library either, but that seems to be a SQL expression executed on the database server. It's basically a copy-paste from the official documentation[0]. So no, not a lambda expression, because it's not computed in Python. As to the extra parentheses: I bet that's a force-of-habit thing to prevent potential issues. For example, it seems Sqlite requires them for exactly this kind of default definition[1]. It could also read to nasty bugs when the lack of parentheses in the resulting SQL could result in a different parse than expected[2]. Adding them just-to-be-safe isn't the worst thing to do. [0]: https://docs.sqlalchemy.org/en/13/core/metadata.html https://docs.sqlalchemy.org/en/13/core/metadata.html [1]: https://github.com/sqlalchemy/sqlalchemy/issues/4474 https://github.com/sqlalchemy/sqlalchemy/issues/4474 [2]: https://github.com/sqlalchemy/sqlalchemy/issues/5344 https://github.com/sqlalchemy/sqlalchemy/issues/5344

nikonyrh 2y ago
Aah that makes sense, thanks!