CODEWITHSUNDEEP
javascriptnode.jsexpresspromise
Raffaeu
Raffaeu

Reputation: 6973

Node.js Express, Error handling works only with console.error

I am using Node.js Express to create some HTTP REST APIs. I have methods that call an underline service that returns a Promise as following:

function getAllApps(request, response) {
    appService.getAllApps(request.query.$expand).then(function (apps) {
           response.status(200).send(apps);
        })
}

and I map the method as following:

var api = express.app;
api.get('/apps', getAllApps);

Now, I have introduced error handling as following:

function getAllApps(request, response) {
    appService.getApps(request.query.$expand).then(function (apps) {
        response.status(200).send(apps);
        })
        .catch(function (err) {
            console.error('Error occurred in Apps Api: ' + err);
            response.status(400).send(err);
    });
}

Which is working as expected except that when an error is encountered, I get the full error stack in the console as following:

Express is listening on 127.0.0.1:3000
Web Api ready

Error occurred in Apps Api: Error: Actions is not defined on the model.

But my HTTP method return 400 and the body is empty, it contains only the curly brackets:

{}

Upvotes: 1

Views: 1034

Answers (2)

Tamas Hegedus
Tamas Hegedus

Reputation: 29916

It is caused by the error object not having enumerable properties, so JSON.stringify(new Error("my message")) will return {}. To get the same as the console output, you have to coerect the error object to a string, like so:

.catch(function (err) {
  console.error('Error occurred in Apps Api: ' + err);
  response.status(500).send("" + err);
});

PS: you should use status(500) for internal errors.

EDIT

If this case does not need a separate error handling mechanism, you could let express to handle your errors:

function getAllApps(request, response, next) {
  appService.getApps(request.query.$expand).then(function (apps) {
    response.status(200).send(apps);
  })
  .catch(function (err) {
    next(err || new Error("Unknown error"));
  });
}

And if express' default error handling doesn't give you satisfying results, you can register your own error handler:

...

// note that the middleware having 4 parameters makes it an error handler
app.use(function(err, req, res, next) {
  console.error('Error occurred in Apps Api: ' + err);
  response.status(500).send("" + err);
});

Upvotes: 3

Mark Omoniyi Adesina
Mark Omoniyi Adesina

Reputation: 92

Remove the status 400 like so:

function getAllApps(request, response) {
  appService.getApps(request.query.$expand).then(function (apps) {
    response.status(200).send(apps);
    })
    .catch(function (err) {
        console.error('Error occurred in Apps Api: ' + err);
        response.json('Error occurred in Apps Api: ' + err);
  });
}

Upvotes: -1

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