try catch inside axios in then method in node js

Question

• after I hit the below api call I am getting errors. (node:5548) UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 1): Error: Can't set headers after they are sent. (node:5548) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.
  • so I put try catch inside my then method but still I am not able to catch the errors inside my catch.
  • I debugged by putting console console.log("try catch error--->", error), but still no help
  • can you let me know whether I have added try and catch properly inside my then method.
  • providing my code snippet below

   axios.get(AppConstants.GET_JWT_TOKEN_URL, {
        auth: {
            username: credentials.auth.racfId, password: credentials.auth.password
        }
    })
        .then((jwtResponse) => {
            console.log("jwt then----->", jwtResponse.data.jwt);
            var jwtToken = `Bearer ${jwtResponse.data.jwt}`;
            //   var jwtToken = `Bearer ewefewehjefwwe wehwefwefwef uih uihu`;
            console.log('then formatUrl --->', formatUrl);

            axios.get(formatUrl, {
                headers: {
                    "Authorization": jwtToken, "Content-Type": 'application/json'

                }
            })

                .then((response) => {
                    try {
                        console.log("sports suceess then0--->");
                        const file = Buffer.from(response.data.content, 'base64');
                        const fileType = mime.contentType(response.data.contentInfo.fileType);
                        const fileExtension = response.data.contentInfo.fileType.toLowerCase();
                        const fileName = `filename=${response.data.contentInfo.id}.${fileExtension}`;
                        console.log("sports suceess fileName--->", fileName);
                        ResponseUtil.callService(res, url);

                        res.send({});
                    }
                    catch (error) {
                        console.log("try catch error--->", error)
                        const errorMessage = error.response.data.message;


                    }

                })


                .catch((e) => {
                    console.log("e catch sports0--->", e);
                    console.log("e.message catch sports0--->", e.message);

                    console.log("catch sports--->", e.response);

                    if (e.response) {
                        return res.status(e.response.status).send(e.response.data);
                    }
                    res.status(500).send(e.message || 'Something wrong');
                });



        });

logs

sports suceess then0--->

sports suceess fileName---> ioreioreio=erierioerioerio
  callService ===>  /erpoperoperop/rejklerklkler
  else if responseutil.jsURL ===>  http://players/erpoperoperop/rejklerklkler
  URL ===>  http://players/erpoperoperop/rejklerklkler
express deprecated res.send(status, body): Use res.status(status).send(body) instead server\services\utils\ResponseUtil.js:56:30
(node:5548) UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 1): Error: Can't set headers after they are sent.
(node:5548) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.

Answer 1

There are a couple of issues with this implementation. The first issue is that you've neglected to return your promises so that they are applied to the promise chain. If you do not return the promise, then errors will not propagate up the promise chain, which defeats the purpose of promises. The second issue is that you're attempting to send a response twice, once in ResponseUtil.callService(res, url) and another time directly after that (e.g. res.send({});).

The console errors point out both of these mistakes:

1) Failure to chain the promises

(node:5548) UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 1): Error: Can't set headers after they are sent.

2) Duplicate call to res.send

express deprecated res.send(status, body): Use res.status(status).send(body) instead server\services\utils\ResponseUtil.js:56:30

---

I'm going to make the assumption that ResponseUtil.callService(res, url) returns a promise to answer this question since it appears that is the case.

axios.get(AppConstants.GET_JWT_TOKEN_URL, {
    auth: {
        username: credentials.auth.racfId,
        password: credentials.auth.password
    }
}).then((jwtResponse) => {
    // Return the promise from get so it is applied to the promise chain
    return axios.get(formatUrl, {
        headers: {
            "Authorization": `Bearer ${jwtResponse.data.jwt}`,
            "Content-Type": 'application/json'

        }
    }).then((response) => {
        const file = Buffer.from(response.data.content, 'base64');
        const fileType = mime.contentType(response.data.contentInfo.fileType);
        const fileExtension = response.data.contentInfo.fileType.toLowerCase();
        const fileName = `filename=${response.data.contentInfo.id}.${fileExtension}`;
        // Return the promise from call service so it is applied to the promise chain
        return ResponseUtil.callService(res, url);
    });
}).catch((e) => {
    // Catch any error that occurred in the promise chain...
    if (e.response) {
        return res.status(e.response.status).send(e.response.data);
    }
    return res.status(500).send(e.message || 'Something wrong');
});