javascript - “发送到客户端后无法设置 header ” - 我正在设置 header ，但找不到位置

Question

当我在使用身份验证中间件时尝试POST时，收到错误在将 header 发送到客户端后无法设置 header 。我进行了研究，发现我正在向客户发送数据，而我并不认为是这样。但我无法弄清楚这是在哪里发生的。我认为它在实际的中间件代码中，因为当我在没有中间件的情况下运行代码时，它可以完美地工作。 请原谅我打字不好。这是一项正在进行的工作。我仍在计算我将收到哪些元素。

路线
app.post("/users/post-item",authenticate, itemController.postItem);

身份验证中间件

export const authenticate = async (
  req: Request,
  res: Response,
  next: NextFunction
) => {
  const token: any = req.headers["token"];
  if (!token) {
    console.log("No token");
    return res.status(400).send({ message: "Token is not provided" });
  }

  try {
    const decoded: any = await jwt.verify(token, "abc123");
    const user = await db("user").where({ id: decoded.id.id });

    req.body.user = { user };
    next();
  } catch (error) {
    return res.status(400).send(error);
  }
  next();
};

Controller

export const postItem = (req: Request, res: Response) => {
  const { itemName, price, description, user, location, species } = req.body;

  try {
    items
      .postItem({
        itemName: itemName,
        price: price,
        description: description,
        userId: user.user[0].id,
        location: location,
        species: species
      })
      .then((data: any) => {
        // Header is sent somewhere before here
        res.sendStatus(200);
      });
  } catch (error) {
    throw new Error(`Something went wrong: ${error}`);
  }
};

PostItem函数

export const postItem = ({
  itemName,
  price,
  description,
  userId,
  location,
  species
}: {
  itemName: string;
  price: string;
  description: string;
  userId: string;
  location: string;
  species: string;
}): any => {
  return db("item_for_sale").insert({
    name: itemName,
    price,
    description,
    user_id: userId,
    location,
    species
  });
};```

Answer 1

您也在 try..catch 之后调用 next()。因此 next 函数被调用两次。

  try {
    const decoded: any = await jwt.verify(token, "abc123");
    const user = await db("user").where({ id: decoded.id.id });

    req.body.user = { user };
    next();
  } catch (error) {
    return res.status(400).send(error);
  }
  next();//<<<<====this next