异步请求中的 angularjs 简单 .then 或 $q 服务

问题描述

我不知道 AngularJS $q 服务和在异步请求后简单地使用 .then() 之间的确切区别是什么.

I don't know what is the exactly difference between AngularJS $q service and simply using .then() after async request.

带有 .then() 的简单示例:

function InboxService($http) {
  this.getEmails = function getEmails() {
    return $http.get('/emails');
  };
}

当使用服务时(只是代码的一部分):

And when using the service (just part of code):

InboxService.getEmails()
.then(function (response) {
  // use response
});

与$q服务解决和拒绝有什么区别?

推荐答案

我假设您在询问 var deferred = $q.defer() 与后续 deferred.resolve() 或 deferred.reject()?在这种情况下，答案是您不需要它，因为您已经拥有 $http 服务返回的承诺对象.事实上，不推荐使用 $q 手动构建另一个新的 Promise 并且被认为是 反模式.

I assume you are asking about the usage of var deferred = $q.defer() with subsequent deferred.resolve() or deferred.reject()? In this case, the answer is that you don't need it since you already have a promise object returned by $http service. In fact, manually constructing another new promise with $q is not recommended and considered an anti-pattern.

如果您使用尚未包装到 promise 中的异步函数(超时、ajax 请求)，那么您可能希望使用 $q 来创建和返回承诺.但是再一次，在您的情况下，您不需要它，因为 $http 服务为您构造了承诺，而另外一个只是多余的.

In cases where you work with asynchronous functions (timeouts, ajax-requests) that are not already wrapped into promise, then this is a case when you might want to use $q to create and return promise. But once again, in your case you don't need it as $http service constructs promise for you and one more is simply redundant.

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