查询承诺的问题

Question

在这个函数中，我应该从我的数据库（mariaDB）中获取一些数据，然后对该结果执行另一个查询。这一切都应该发送回前端

pool.getConnection()
        .then(conn => {
            conn.query(query)
                .then((rows) => {
                    console.log(`=== Request from: ${req.query.hostname} (${req.query.ip}) at ${new Date().toISOString().replace("T", " ")} => (CORRECT)`);

                    rows = rows.map((item) => {
                        switch (expectedReturnType) {
                            case "multiple":
                                conn.query(`
                                    SELECT utente.nome, utente.cognome
                                    FROM creatore_compito
                                             JOIN utente ON utente.id = creatore_compito.id_creatore
                                    WHERE creatore_compito.id_compito = ${item.id}
                                `).then(rows => {
                                    return Object.assign(item, {
                                        "verifica": item["verifica"] === 0 ? "compito" : "verifica",
                                        "creatori": rows
                                    });
                                }).catch(err => {
                                    return err;
                                });
                                break;
                            case "single":
                                return item["verifica"] === 0 ? "compito" : "verifica"
                            default:
                                throw new TypeError(`"${expectedReturnType}" is not a valid type for "expectedReturnType"`)
                        }
                    });

                    res.send(rows);
                })
                .catch(err => {
                    console.log(`=!= Request from: ${req.query.hostname} (${req.query.ip}) at ${new Date()} => (ERROR) ${err}`);
                    res.status(500).send(err);
                })
                .finally(() => {
                    conn.end();
                })
        })
        .catch(err => {
            console.log(`=!= Request from: ${req.query.hostname} (${req.query.ip}) at ${new Date()} => (ERROR) ${err}`);
            res.status(500).send("connection error");
        });

然而，我注意到

res.send()

是在

.map()

执行结束之前执行的。我试过以不同的方式使用 await

Promise.All()

但我找不到解决方案，因为结果总是

null