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Error Handling

By default Feathers just uses the default error handler that comes with Express. It's pretty basic so the feathers-errors module comes bundled with a more robust error handler that you can use in your app. This error handler is the one that is included in a generated Feathers app by default.

ProTip: Because Feathers extends Express you can use any Express compatible error middleware with Feathers. In fact, the error handler bundled with feathers-errors is just a slightly customized one.

Many Feathers plugins (like the database adapters and authentication) already throw Feathers errors, which include their status codes. The default error handler sends a JSON representation of the error (without the stacktrace in production) or sends a default 404.html or 500.html error page when visited in the browser.

If you want to use your own custom error pages you can do with a custom HTML formatter like this:

const error = require('feathers-errors/handler');
const app = feathers();

// Just like Express your error middleware needs to be
// set up last in your middleware chain.
app.use(error({
    html: function(error, req, res, next) {
      // render your error view with the error object
      res.render('error', error);
    }
}))

ProTip: If you want to have the response in json format be sure to set the Accept header in your request to application/json otherwise the default error handler will return HTML.

Options

The following options can be passed when creating a new localstorage service:

  • html (Function|Object) [optional] - A custom formatter function or an object that contains the path to your custom html error pages.

ProTip: html can also be set to false to disable html error pages altogether so that only JSON is returned.

Catching Global Server Side Errors

Promises swallow errors if you forget to add a catch() statement. Therefore, you should make sure that you always call .catch() on your promises. To catch uncaught errors at a global level you can add the code below to your top-most file.

process.on('unhandledRejection', (reason, p) => {
  console.log("Unhandled Rejection at: Promise ", p, " reason: ", reason);
});

Feathers Error Types

feathers-errors currently provides the following error types, all of which are instances of FeathersError:

ProTip: All of the feathers plugins will automatically emit the appropriate Feathers errors for you.

  • BadRequest: 400
  • NotAuthenticated: 401
  • PaymentError: 402
  • Forbidden: 403
  • NotFound: 404
  • MethodNotAllowed: 405
  • NotAcceptable: 406
  • Timeout: 408
  • Conflict: 409
  • Unprocessable: 422
  • GeneralError: 500
  • NotImplemented: 501
  • Unavailable: 503

FeathersError API

Feathers errors are pretty flexible. They contain the following fields:

  • type - FeathersError
  • name - The error name (ie. "BadRequest", "ValidationError", etc.)
  • message - The error message string
  • code - The HTTP status code
  • className - A CSS class name that can be handy for styling errors based on the error type. (ie. "bad-request" , etc.)
  • data - An object containing anything you passed to a Feathers error except for the errors object.
  • errors - An object containing whatever was passed to a Feathers error inside errors. This is typically validation errors or if you want to group multiple errors together.

Here are a few ways that you can use them:

const errors = require('feathers-errors');

// If you were to create an error yourself.
const notFound = new errors.NotFound('User does not exist'));

// You can wrap existing errors
const existing = new errors.GeneralError(new Error('I exist'));

// You can also pass additional data
const data = new errors.BadRequest('Invalid email', {email: '[email protected]'});

// You can also pass additional data without a message
const dataWithoutMessage = new errors.BadRequest({email: '[email protected]'});

// If you need to pass multiple errors
const validationErrors = new errors.BadRequest('Invalid Parameters', {errors: {email: 'Email already taken'} });

// You can also omit the error message and we'll put in a default one for you
const validationErrors = new errors.BadRequest({errors: {email: 'Invalid Email'} });