@wellwelwel I see you added the needs documentation tag. Is this what you had in mind?

I see you added the needs documentation tag. Is this what you had in mind?

Yes, thanks @uPaymeiFixit! I don't know how these types perform in general with variations such as placeholders, nested arrays, and complex parameter combinations, especially in the case of query, which allows for more flexible values. That's why I put the needs investigation label on it.

For TypeScript, there are compilation tests (which do not execute code, but only check types usage), for example:

node-mysql2/test/tsc-build/strict-checks/query.test.ts

Lines 125 to 132 in b78e928

	conn.query<mysqlp.ProcedureCallPacket>(sql).then(([_r, _f]) => {
	const result:
	| [mysqlp.RowDataPacket[], mysqlp.ResultSetHeader]
	| mysqlp.ResultSetHeader = _r;
	const fields: mysqlp.FieldPacket[] = _f;
	console.log(result, fields);
	});

You can run them with test:tsc-build 🙋🏻‍♂️

Awesome! I ran the test:tsc-build script and it looks like it succeeded (exited with 0).
As far as investigation goes, I initially did a lot of playing around with the type to make sure it was accurate. I think it should reflect what types are actually possible. Here's a tsplayground that shows what's possible and what's not.

@uPaymeiFixit, my main concern was how these types would behave with named-placeholders. By migrating the entire ESM test suite to TypeScript in #4086, the types you created are now tested. You can check it with npm run typecheck 🙋🏻‍♂️

Good catch, I completely forgot about named placeholders. In case it's helpful, I also updated my tsplayground test.

Thanks again, @uPaymeiFixit!

Just to be sure, I tried a random case with nested arrays:

query('INSERT ...', ['john', 30, [[[{a: true}], 6]]]); // ✅