javascript - Firebase 'Unhandled Rejection' 和 'Can' t 在设置 header 后设置“JavaScript 错误

Question

首先，请注意，我对 JS 和编码非常陌生:)

期望的行为:我编写了以下 JS HTTPS Firebase 函数，该函数接受查询参数 locationId，执行 GET API 调用并将响应保存回 Firebase。该代码根据需要正确地将数据保存到 Firebase。我遇到过类似的问题，但我正在努力使这些解决方案适应我下面的具体问题。据我所知，我只发送一次响应。

具体错误:以下是控制台输出

Cannot set headers after they are sent to the client

Unhandled rejection

我的功能:

exports.doshiiGetMenuForOnboardedVenue = functions.https.onRequest((req, res) => {

  // Forbidding PUT requests.
  if (req.method === 'PUT') {
    return res.status(403).send('Forbidden!');
  }

  cors(req, res, () => {

    const locationId = req.query.locationId;

    console.log('locationId', locationId);

    if (locationId){

      console.log('locationId', locationId);

      var token = jwttoken();

      const options = {
          headers: {
            'content-type': 'application/json',
            'authorization': 'Bearer ' + token}
        };

        const uri = 'https://sandbox.doshii.co/partner/v3/locations/' + locationId + '/menu?lastVersion=:lastVersion&filtered=true'

        axios.get(uri, options)
          .then(response => {

             return admin.database().ref(`/venue-menus/${locationId}/`).set(response.data)
             .then(response => {
               return res.status(200).send(locationId)
             })
             .catch(err => {
               return res.status(500).send({error: err})
             })

          })
          .then(response => {
                    return res.status(200).send(locationId)
            })
          .catch(err => {
            return res.status(500).send({error: err})
          })//end axios

    } else {

      return res.status(500).send({error: 'locationId missing'})

    }//end if-else (!locationId)

  })//end cors

});

Answer 1

通过展平嵌套的 Promise，您可以看到代码正在执行以下指令(当 axios 调用不抛出错误时):

admin.database().ref(`/venue-menus/${locationId}/`).set(response.data))
  .then(response => res.status(200).send(locationId))
  .catch(err => res.status(500).send({error: err})
  .then(response => res.status(200).send(locationId)) // this line is always called after either of the above.
  .catch(err => res.status(500).send({error: err})

作为一般实践，除非需要，否则您不应将 Promise 嵌套在它们自己的 then() 和 catch() 处理程序中，因为这会导致像这样的奇怪效果。

此外，如果您的代码要求使用 //end axios 或 //end cors 消息，您应该展平您的代码，以便在没有这些消息的情况下也有意义。

调整您的代码以“快速失败”，更正您的 API 响应并适当隐藏错误堆栈跟踪可以提供:

const cors = require('cors')({
  origin: true,
  methods: ["GET"]
});


exports.doshiiGetMenuForOnboardedVenue = functions.https.onRequest((req, res) => {
  cors(req, res, (err) => { // note: cors will handle OPTIONS method

    if (err) {
      // note: log full error at ERROR message level
      console.error('Internal CORS error:', err);
      // note: return only generic status message to client
      return res.status(500).json({error: 'Internal Server Error'});
    }

    // Forbidding anything but GET requests.
    if (req.method !== 'GET') {
      // 405 METHOD_NOT_ALLOWED
      return res.status(405)
        .set('Allow', 'GET')
        .json({error: 'Not Allowed!'});
    }

    const locationId = req.query.locationId;

    console.log('locationId', locationId);

    if (!locationId) {
      // 400 BAD_REQUEST
      return res.status(400).json({error: 'locationId missing'})
    }

    var token = jwttoken();

    const options = {
        headers: {
          'content-type': 'application/json',
          'authorization': 'Bearer ' + token
        }
      };

    // note: Don't forget to enable billing for third-party APIs!
    const uri = 'https://sandbox.doshii.co/partner/v3/locations/' + locationId + '/menu?lastVersion=:lastVersion&filtered=true'

    axios.get(uri, options)
      .then(response => admin.database().ref(`/venue-menus/${locationId}/`).set(response.data))
      .then(() => {
        // note: as locationId was already sent by the client, send new/useful
        // information back or nothing but the right status code
        res.status(200).json({ ref: `/venue-menus/${locationId}/` });
      })
      .catch(err => {
        // note: log full error at ERROR message level
        console.error('Failed to retrieve/save API data:', err);
        // note: return only message to client
        res.status(500).json({error: err.message || 'Internal Server Error'});
      });
  });
});