AngularJS: $q wait for all even when 1 rejected

Question

I\'ve been trying to wait for a couple of promises with Angular\'s $q but there seems to be no option to \'wait for all even when a promis is rejected\'. I\'ve created an exampl

Answer 1

A simple solution would be to use catch() to handle any errors and stop rejections from propagating. You could do this by either not returning a value from catch() or by resolving using the error response and then handling errors in all(). This way $q.all() will always be executed. I've updated the fiddle with a very simple example: http://jsfiddle.net/pHEf9/125/

...
function handleError(response) {
    console.log('Handle error');
}

// Create 5 promises
var promises = [];
var names = [];
for (var i = 1; i <= 5; i++) {
    var willSucceed = true;
    if (i == 2) willSucceed = false;
    promises.push(
      createPromise('Promise' + i, i, willSucceed).catch(handleError));
}
...

Be aware that if you don't return a value from within catch(), the array of resolved promises passed to all() will contain undefined for those errored elements.

Answer 2

Analogous to how all() returns an array/hash of the resolved values, the allSettled() function from Kris Kowal's Q returns a collection of objects that look either like:

{ state: 'fulfilled', value: <resolved value> }

or:

{ state: 'rejected', reason: <rejection error> }

As this behavior is rather handy, I've ported the function to Angular.js's $q:

angular.module('your-module').config(['$provide', function ($provide) {
    $provide.decorator('$q', ['$delegate', function ($delegate) {
        var $q = $delegate;

        $q.allSettled = $q.allSettled || function allSettled(promises) {
            // Implementation of allSettled function from Kris Kowal's Q:
            // https://github.com/kriskowal/q/wiki/API-Reference#promiseallsettled

            var wrapped = angular.isArray(promises) ? [] : {};

            angular.forEach(promises, function(promise, key) {
                if (!wrapped.hasOwnProperty(key)) {
                    wrapped[key] = wrap(promise);
                }
            });

            return $q.all(wrapped);

            function wrap(promise) {
                return $q.when(promise)
                    .then(function (value) {
                        return { state: 'fulfilled', value: value };
                    }, function (reason) {
                        return { state: 'rejected', reason: reason };
                    });
            }
        };

        return $q;
    }]);
}]);

Credit goes to:

• Zenuka for the decorator code
• Benjamin Gruenbaum for pointing me in the right direction
• The all implementation from Angular.js source