AngularJS 的承诺 [英] AngularJS promise

问题描述

AngularJS 文档 说:

AngularJS docs say:

$q 承诺被模板引擎以 angular 识别，这意味着在模板中，您可以将附加到作用域的承诺视为结果值.

$q promises are recognized by the templating engine in angular, which means that in templates you can treat promises attached to a scope as if they were the resulting values.

那么有人可以解释一下这个 fiddle 不起作用的原因吗?无法更改文本字段值.但是将 $http 服务返回到作用域字段的承诺分配给它就像一个魅力.

So could someone please explain the reason this fiddle not working? It's not possible to change text field value. But assigning promises that $http service returns to a scope field works like a charm.

控制器:

function MyController($scope, $q, $timeout) {
    this.getItem = function () {
        var deferred = $q.defer();
        deferred.resolve({
            title: 'Some title'
        });
        return deferred.promise;
    };

    $scope.item = this.getItem();
}

HTML:

<input type="text" ng-model="item.title">

推荐答案

需要在promise对象上使用then()函数:

You need to use the then() function on the promise object:

this.getItem().then(function(result) {
   $scope.item = result;
});

就你而言，我认为你不需要承诺.Angular 的 $watch 系统会处理事情.只需在函数中返回一个对象，而不是原始类型:

In your case I don't think you need a promise. Angular's $watch system will take care of things. Just return an object in your function, not a primitive type:

this.getItem = function () {
    var item = {};

    // do some async stuff
    $http.get(...).success(function(result) {
       item.title = result;
    });
    return item;
};

$scope.item = this.getItem();

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