Question

作为扩展of a question I asked earlier（感谢所有帮助！），
我无法让我的第二个承诺工作（在一个3或更多的链中）我查看了this，this，但无法获得我当前代码的任何线索

应用和控制器看起来像：

myApp.controller('Controller_1', function($scope, myService) {

    var myName = "Ben";

    myService.slowService(myName)
    .then(function(result){myService.slowService2(result);})
    .then(function(result){myService.fastService(result);});

    $scope.myName = myName;
});

服务提供商看起来像：

myApp.service('myService', function($q, $timeout) {

    this.slowService = function (name) {
        var deferred = $q.defer();
        console.log('Start of slowService1:', name, Date.now());

        $timeout(function() {
            name = 'Hello, ' + name + " is learning Angularjs";
            alert(name); 
            deferred.resolve(name);
                console.log('End of slowService1 timeout:', name, Date.now());
        }, 1500);

        return deferred.promise;
    };

    this.slowService2 = function (name) {
        var deferred = $q.defer();
        console.log('Start of slowService2:', name, Date.now());

        $timeout(function() {
            name = 'Hello, ' + name + " is learning Angularjs";
            alert(name); 
            deferred.resolve(name);
                console.log('End of slowService2 timeout:', name, Date.now());
        }, 1000);

        return deferred.promise;
    };

    this.fastService = function(name){ 
        var deferred = $q.defer();
            console.log('Start of fastService:', name, Date.now());
        alert('Hello ' + name + ' - you are quick!'); 
        deferred.resolve();
            console.log('End of fastService:', name, Date.now());
        return deferred.promise;
    };
});

控制台输出如下：

Start of slowService1: Ben 1420877247858
End of slowService1 timeout: Hello, Ben is learning Angularjs 1420877250982
Start of slowService2: Hello, Ben is learning Angularjs 1420877250983
Start of fastService: undefined 1420877250984
End of fastService: undefined 1420877251641
End of slowService2 timeout: Hello, Hello, Ben is learning Angularjs is learning Angularjs 1420877254148

因此，当第一个slowService1 $ q.defer（）工作时，第三个函数fastService不会等待第二个slowService2延迟对象在开始之前解析... ？

jsfiddle是here

PS $ timeout仅用于模拟$ http调用和SQLite查询等。

Answer 1

您需要return承诺，以便与.then链接：

myService.slowService(myName)
    .then(function(result){
        return myService.slowService2(result);
     })
    .then(function(result){
        myService.fastService(result);
     });

AngularJS：承诺链不会推迟过去的第二个功能

1 个答案: