javascript - 类型错误 : Cannot call method 'then' of undefined Angularjs

Question

我是 Angular 的新手，在进行同步操作时遇到了问题。我已经解决了 Angular Controller 出现的几个问题，我从 newController 文件中得到错误“无法调用未定义的方法”。

angular.module('newApp.newController', ['angularSpinner', 'ui.bootstrap'])

.controller('newController', function($q, $scope, utilityFactory, $http) {
    utilityFactory.getData().then(function(data) {

        console.log("success");
        console.log(data);

    });
});


angular.module('newApp.utility', [])
    .factory('utilityFactory', function($q, $http) {

        var utils = {};

        //This is a cordova plugin
        var getLauncher = function() {
            return window.plugin.launcher;
        };

        var success = function(data) {
            console.log(device);
            return device;
        }
        var fail = function(error) {
            console.log("error", error);
        };

        utils.getData = function() {
            /* Get the store number details initially before initalizing the application */
            if (window.plugin) {
                var launcher = getLauncher();
                console.log("Fetching data from device");
                //Cordova js is returning this method
                return launcher.getDevice(success, fail);
            }
        };
        return utils;
    })

Answer 1

基于以下理解:

Launcher.prototype.getDevice = function(successCallback, failureCallback) {
    exec(successCallback, failureCallback, KEY, 'getDevice', []);
}

，我们知道 window.plugin.launcher.getDevice() 返回 undefined，而不是数据对象。相反，它通过成功/失败回调提供响应。

因此，要使用 promises，window.plugin.launcher.getDevice() 需要“promified”，包括显式创建 new Promise()及其通过 .getDevice 回调的解决/拒绝。 (简单地包装在 $q(...) 中不是一回事，也行不通)。

angular.module('newApp.utility', []).factory('utilityFactory', function($q, $http) {
    return {
        getDevice: function() {
            return $q.defer(function(resolve, reject) {
                window.plugin.launcher.getDevice(resolve, reject); // If this line throws for whatever reason, it will be automatically caught internally by Promise, and `reject(error)` will be called. Therefore you needn't explicitly fork for cases where `window.plugin` or `window.plugin.launcher` doesn't exist.
            }).promise;
        }
    };
});

从 Controller 调用现在应该可以工作了:

angular.module('newApp.newController', ['angularSpinner', 'ui.bootstrap']).controller('newController', function($q, $scope, utilityFactory, $http) {
    return utilityFactory.getDevice().then(function(data) {
        console.log(data);
    }).catch(function(error) {
        console.error(error);
    });
});