In a previous AngularJS app that I am migrating to Angular 8, I had a function that would download functions by binding them and placing them in an array, waiting to be called using a reduce function.(在我要迁移到Angular 8的以前的AngularJS应用程序中，我有一个函数可以通过将函数绑定并放置在数组中来下载函数，等待使用reduce函数调用。)
For example:(例如：)
function stageForDownload() {
$scope.files.forEach(function (file) {
if (file.checked) {
$scope.downloadFunctions.push(downloadFile.bind(null, file));
}
});
}
function downloadStaged() {
$scope.downloadFunctions.reduce(
function (prev, next) {
return prev.then(next);
}, Promise.resolve())
.then( /* do something now that all files are downloaded */ );
}
}
This code would essentially resolve promises in a one by one fashion until the list of functions were empty.(此代码本质上将以一种一种方式解决承诺，直到函数列表为空。) As in Angular 8, the structure of promises works in a different way (meaning they use the ECMA 6 implementation now) and I am unsure of how to migrate this code.(与Angular 8中一样，promise的结构以不同的方式工作（这意味着它们现在使用ECMA 6实现），我不确定如何迁移此代码。) Furthering my confusion, the HttpClient angular provides now returns an Observable which can be subscribed to;(更令人困惑的是，HttpClient所提供的角度现在返回了一个可以订阅的Observable；) and while rsjx's forkJoin() method seems to support exactly what I want to do, it will not accept a list of bound functions.(尽管rsjx的forkJoin()方法似乎完全支持我想做的事情，但它不会接受绑定函数的列表。)
I simply just need to know when all of the functions are completed, as they are voids that run an export service method to download a file.(我只需要知道所有功能何时完成，因为它们是运行导出服务方法下载文件的空白。) So I do not necessarily need to return / subscribe to any data from these methods that are being reduced.(因此，我不一定需要从减少的这些方法中返回/订阅任何数据。)
Edit:(编辑：)
There are two more functions involved that I forgot to mention.(我忘了提到另外两个功能。) Here is downloadFile, which is responsible for calling the exportService.(这是downloadFile，它负责调用exportService。)
function downloadFile(file) {
var deferred = $q.defer();
$scope.date = formatDate($scope.datepicker.selectedDate);
$scope.fileDate = dateToYMD($scope.datepicker.selectedDate);
exportService.exportData(file.FileNamePrefix + " " + $scope.fileDate + ".xlsx", 'SOME_API_LOCATION' + $scope.date, file).then(
function () {
deferred.resolve();
},
function (error) {
deferred.reject();
notificationService.displayError("Internal Error!");
});
return deferred.promise;
}
And here is the exportService itself:(这是exportService本身：)
(function (app) {
'uuse strict';
app.factory('exportService', exportService);
exportService.$inject = ['$q', '$http'];
function exportService($q, $http) {
var service = {
exportData: exportData,
createFilename: createFilename
};
function exportData(filename, url, data) {
var config = {
responseType: 'arraybuffer'
};
return $http.post(url, data, config).then(
function (response) {
var deferred = $q.defer();
var data = response.data;
var status = response.status;
var headers = response.headers();
var octetStreamMime = 'application/octet-stream';
var success = false;
var contentType = headers['content-type'] || octetStreamMime;
try {
// Try using msSaveBlob if supported
var blob = new Blob([data], { type: contentType });
if (navigator.msSaveBlob)
navigator.msSaveBlob(blob, filename);
else {
// Try using other saveBlob implementations, if available
var saveBlob = navigator.webkitSaveBlob || navigator.mozSaveBlob || navigator.saveBlob;
if (saveBlob === undefined) throw "Not supported";
saveBlob(blob, filename);
}
success = true;
deferred.resolve();
} catch (ex) {
}
if (!success) {
// Get the blob url creator
var urlCreator = window.URL || window.webkitURL || window.mozURL || window.msURL;
if (urlCreator) {
// Try to use a download link
var link = document.createElement('a');
if ('download' in link) {
// Try to simulate a click
try {
// Prepare a blob URL
var blob = new Blob([data], { type: contentType });
var url = urlCreator.createObjectURL(blob);
link.setAttribute('href', url);
// Set the download attribute (Supported in Chrome 14+ / Firefox 20+)
link.setAttribute("download", filename);
// Simulate clicking the download link
var event = document.createEvent('MouseEvents');
event.initMouseEvent('click', true, true, window, 1, 0, 0, 0, 0, false, false, false, false, 0, null);
link.dispatchEvent(event);
success = true;
deferred.resolve();
} catch (ex) {
}
}
if (!success) {
// Fallback to window.location method
try {
var blob = new Blob([data], { type: octetStreamMime });
var url = urlCreator.createObjectURL(blob);
window.location = url;
success = true;
deferred.resolve();
} catch (ex) {
deferred.reject();
}
}
}
}
return deferred.promise;
},
function (error) {
return $q.reject(error);
});
}
}
})(angular.module('app'));
So it appears my problem is not necessarily firing off a dynamically created list of http requests, but rather how to convert promises using $q into ECMA6+ promises.(因此，看来我的问题不一定是启动动态创建的HTTP请求列表， 而是如何使用$ q将诺言转换为ECMA6 +诺言。)
ask by Tyler Lyle translate from so
与恶龙缠斗过久,自身亦成为恶龙；凝视深渊过久,深渊将回以凝视…
