錯誤：發送后無法設置標頭。 發布數據

Question

我正在使用此 API 發布公寓數據，正在注冊數據，但我總是收到錯誤消息：“發送后無法設置標題。”

我該如何解決這個實現以避免這種情況？ 我用所有堆棧補充了代碼以訪問這個 API。

app.use(cors());
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: true }));

app.get('/apartment', (req, res) => {
  Apartment.findAll({
    attributes: [
      'apartment_id',
      'apartment_floor',
      'apartment_size',
      'apartment_block_id',
      'apartment_block_name',
      'apartment_parking_id',
    ],
  })
    .then((apartments) => {
      //      console.log(documents);
      res.sendStatus(200).send(apartments);
    })
    .catch((err) => console.log('erro: ', err));
});

app.get('/apartment/:apartment', (req, res) => {
  Apartment.findByPk(
    {
      attributes: [
        'apartment_id',
        'apartment_block_id',
        'apartment_floor',
        'apartment_size',
        'apartment_block_name',
        'apartment_parking_id',
      ],
      where: {
        apartment_id: req.params.apartment_id,
        apartment_block_id: req.params.apartment_block_id,
      },
    },
  )
    .then((documents) => {
      res.sendStatus(200).send(documents);
    })
    .catch((err) => console.log("erro - API GET '/document: ", err));
});
app.post('/apartment', (req, res) => {
  if (!req.body) {
    return res.sendStatus(400).send({
      message: 'Content can not be empty!',
    });
  } else {
    Apartment.create({
      apartment_id: req.body.apartment_id,
      apartment_block_id: req.body.apartment_block_id,
      apartment_block_name: req.body.apartment_block_name,
      apartment_floor: req.body.apartment_floor,
      apartment_size: req.body.apartment_size,
      apartment_parking_id: req.body.apartment_parking_id,
    });
  }
  return res
    .sendStatus(200)
    .send({ message: ' [CREATED REGISTER] API POST:  /apartment' });
});
app.listen(config.port, () =>
  console.log(`Server listening on port ${config.port}!`),
);

Answer 1

嘗試在 res.... 之前添加return

return res.sendStatus(400).send({
      message: 'Content can not be empty!',
    });

Answer 2

你的代碼：

res.sendStatus(200).send(apartments);

相當於：

res.status(200).send('OK').send(apartments)

這意味着您嘗試發送兩次響應：

res
  .status(200) // Set status code of response
  .send('OK') // Send the response!
  .send(apartments) // Error: Can't set headers after they are sent

嘗試設置status並使用send ：

res
  .status(200) // Set status code of response
  .send(apartments) // Send the response

還要在所有res.status().send()中添加return以避免每個請求多次嘗試。