获取异步执行的多个promise的状态

I am executing multiple $http calls in parallel (async). My code logic looks something like this -

我正在并行执行多个$ http调用（异步）。我的代码逻辑看起来像这样 -

$scope.ids = [1, 2, 3, 4];
var promises = [];
for(var i in $scope.ids){
    promises.push(
        $http.get('http://0.0.0.0/t2/' + $scope.ids[i])
        );
}

$q.all(promises).then(
    function(res){
        console.log(res);
    },
    function(res){
        console.log(res);
    }
);

Now the $q.all() docs say that

现在$ q.all（）文档说明了这一点

Returns a single promise that will be resolved with an array/hash of values, each value corresponding to the promise at the same index/key in the promises array/hash. If any of the promises is resolved with a rejection, this resulting promise will be rejected with the same rejection value.

返回将使用值的数组/散列解析的单个promise，每个值对应于promises数组/散列中相同索引/键的promise。如果任何承诺通过拒绝得到解决，则此结果承诺将被拒绝并具有相同的拒绝值。

Now when all the promises pass, I get an expected response of an array containing 4 elements.

现在当所有的promise都通过时，我得到一个包含4个元素的数组的预期响应。

Success -> Object[4]

成功 - >对象[4]

However, in the case where all fail, the res output shows only the one which failed.

但是，在全部失败的情况下，res输出仅显示失败的输出。

Failure -> Hash

失败 - >哈希

This is as expected and what the Angular Docs mention.

这是预期的，以及Angular Docs提到的内容。

In my case I want to know the status of all the http request I made, even if it was a failure I require the result. Certainly $q.all() will break out the moment one of the promises fails. I want to wait till all the promises have either passed or failed and then get the results. How do I do this?

在我的情况下，我想知道我所做的所有http请求的状态，即使它是一个失败我需要结果。肯定$ q.all（）会在其中一个承诺失败的那一刻爆发。我想等到所有承诺都通过或失败然后得到结果。我该怎么做呢？

1 个解决方案

#1

An idea is to utilize the error callback of the promise to return a meaningful status:

一个想法是利用promise的错误回调来返回有意义的状态：

function Failure(r) {
    this.response = r;
}

$scope.ids = [1, 2, 3, 4];
var promises = [];
for(var i in $scope.ids){
    promises.push(
        $http.get('http://0.0.0.0/t2/' + $scope.ids[i]).then(
            function(r) {
                return r;
            },
            function failure(r) {
                // this will resolve the promise successfully (so that $q.all
                // can continue), wrapping the response in an object that signals
                // the fact that there was an error
                return new Failure(r);
            }
        );
    );
}

Now $q.all() will always succeed, returning the array of results. Check each result with result[i] instanceof Failure. If this condition is true, there was a failure in that request - get the response doing result[i].response. IT may need some tweaking, but hopefully you get the point.

现在$ q.all（）将始终成功，返回结果数组。使用result [i] instanceof Failure检查每个结果。如果这个条件为真，则该请求失败 - 得到响应结果[i] .response。 IT可能需要一些调整，但希望你明白这一点。