How to use the sqlstring.format function in sqlstring

authController.createUser = (req, res, next) => {
  // Hash password using the salt;
  const hashedPassword = bcrypt.hashSync(req.body.password, SALT_WORK_FACTOR);
  db.query(
    sqlstring.format(
      'INSERT INTO user (username, email, password, firstname, lastname) VALUES (?,?,?,?,?)', [req.body.username, req.body.email, hashedPassword, req.body.firstname, req.body.lastname]), 
    (err, results, fields) => {
      if (err) return res.status(400).send(err);
      else {
        const user_id = results.insertId;
        console.log(user_id);
        const token = jwt.sign(user_id, jwtSecret);
        res.locals.jwt = token;
        return next();
      }
    }
  );
}

format(sql, values) {
    if (typeof this.config.queryFormat === 'function') {
      return this.config.queryFormat.call(
        this,
        sql,
        values,
        this.config.timezone
      );
    }
    const opts = {
      sql: sql,
      values: values
    };
    this._resolveNamedPlaceholders(opts);
    return SqlString.format(
      opts.sql,
      opts.values,
      this.config.stringifyObjects,
      this.config.timezone
    );
  }

toSqlString() {
    const { sql, values } = this.format()
    return SqlString.format(sql, values)
  }

historyController.savePath = (req, res, next) => {
  db.query(
    sqlstring.format(
      'INSERT INTO history (user_id, path) VALUES (?,?)', [res.locals.user_id, JSON.stringify(req.body)]),
    (err, results, fields) => {
      if (err) return res.status(400).send(err);
      else {
        const path_id = results.insertId;
        res.locals.path_id = path_id;
        return next();
      }
    }
  );
}

historyController.checkForPath = (req, res, next) => {
  db.query(
    sqlstring.format(
    'SELECT path_id FROM history WHERE path = ? AND user_id = ?', [JSON.stringify(req.body), res.locals.user_id]),
    (err, results, fields) => {
      if (err) return res.status(400).send(err);
      else {
        if (results.length) {return res.status(400).json({error: 'path already in db'})}
        return next();
      }
    }
  );
}

dbName: string,
  tableName?: string
): Promise {
  let sql = `
  SELECT
    TABLE_NAME, TABLE_TYPE, CREATE_TIME, TABLE_COLLATION, TABLE_COMMENT
  FROM
    INFORMATION_SCHEMA.TABLES
  WHERE UPPER(TABLE_SCHEMA) = ?
`
  let params = [dbName.toUpperCase()]
  if ((tableName?.length ?? 0) > 0) {
    sql += ` AND UPPER(TABLE_NAME) = ?`
    params.push(tableName!.toUpperCase())
  }
  const data = await evalSqlObj(SqlString.format(sql, params))

  return {
    tables: data.map((row) => ({
      name: row.TABLE_NAME,
      type: row.TABLE_TYPE,
      createTime: row.CREATE_TIME,
      collation: row.TABLE_COLLATION,
      comment: row.TABLE_COMMENT,
    })),
  }
}

authController.getUserData = (req, res, next) => {
  db.query(
    sqlstring.format(
      'SELECT firstname, lastname, username, user_id FROM user WHERE user_id = ?', [res.locals.user_id]
    ),
    (err, results, fields) => {
      if (err) return res.status(500).send(err);
      return res.send(results[0]);
    }
  );
}