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sqlite3: Support 'size' keyword argument in Cursor::fetchmany #6118

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coolreader18 merged 2 commits into from
Sep 1, 2025
Merged

sqlite3: Support 'size' keyword argument in Cursor::fetchmany #6118

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a2b194a
sqlite3: Support 'size' keyword argument in `Cursor::fetchmany`
ever0de Sep 1, 2025
2e16f51
use `FromArgs`
ever0de Sep 1, 2025
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2 changes: 0 additions & 2 deletions Lib/test/test_sqlite3/test_dbapi.py
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Original file line number Diff line number Diff line change
Expand Up @@ -1069,8 +1069,6 @@ def test_fetchmany(self):
res = self.cu.fetchmany(100)
self.assertEqual(res, [])

# TODO: RUSTPYTHON
@unittest.expectedFailure
def test_fetchmany_kw_arg(self):
"""Checks if fetchmany works with keyword arguments"""
self.cu.execute("select name from test")
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32 changes: 29 additions & 3 deletions stdlib/src/sqlite.rs
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Expand Up @@ -1684,14 +1684,40 @@ mod _sqlite {
#[pymethod]
fn fetchmany(
zelf: &Py<Self>,
max_rows: OptionalArg<c_int>,
mut args: FuncArgs,
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@youknowone youknowone Sep 1, 2025

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Can #[derive(FromArgs)] be applicable? Or is there any blocker not allowing to do it?

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@ever0de ever0de Sep 1, 2025

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We can change it. However, I believe we can't use the FromArgs derive macro because the error messages would be different.

2e16f51 (#6118)

 --- Testing with too many positional arguments ---
-fetchmany() takes from 0 to 1 positional arguments but 2 were given  (cpython)
+expected at most 2 arguments, got 3 (FromArgs)
 
 --- Testing with an unexpected keyword argument ---
-fetchmany() got an unexpected keyword argument 'unexpected_kw' (cpython)
+Unexpected keyword argument unexpected_kw (FromArgs)
 
 --- Testing with both positional and keyword for the same argument ---
-fetchmany() got multiple values for argument 'size' (cpython)
+Unexpected keyword argument size (FromArgs)

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@ever0de ever0de Sep 1, 2025

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If you think the current error messages are acceptable, I believe we can apply this version as is.

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@coolreader18 coolreader18 Sep 1, 2025

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Yeah, those error messages are fine - there's discrepancy in so many places, that if we wanted to make the error messages line up we'd just change FromArgs all at once.

vm: &VirtualMachine,
) -> PyResult<Vec<PyObjectRef>> {
let max_rows = max_rows.unwrap_or_else(|| zelf.arraysize.load(Ordering::Relaxed));
let size_posarg = args.take_positional();
let size_kwarg = args.take_keyword("size");

if !args.args.is_empty() {
return Err(vm.new_type_error(format!(
"fetchmany() takes from 0 to 1 positional arguments but {} were given",
args.args.len() + 1
)));
}

if let Some((name_str, _)) = args.kwargs.into_iter().next() {
return Err(vm.new_type_error(format!(
"fetchmany() got an unexpected keyword argument {name_str}",
)));
}

let max_rows: c_int = match (size_posarg, size_kwarg) {
(Some(pos), None) => pos.try_into_value(vm)?,
(None, Some(kw)) => kw.try_into_value(vm)?,
(None, None) => zelf.arraysize.load(Ordering::Relaxed),
(Some(_), Some(_)) => {
return Err(vm.new_type_error(
"fetchmany() got multiple values for argument 'size'".to_owned(),
));
}
};

let mut list = vec![];
while let PyIterReturn::Return(row) = Self::next(zelf, vm)? {
list.push(row);
if list.len() as c_int >= max_rows {
if max_rows > 0 && list.len() as c_int >= max_rows {
break;
}
}
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