javascript - Angularjs 在服务中使用 Promise

Question

我有一个页面多次调用 api 以返回一页的记录。信息量很大，加载需要时间。我正在尝试链接 promise ，以便在显示数据的页面加载之前给数据加载时间。我使用以下代码来调用第一部分:

$scope.selectAll = function () {
    alert('Please wait while your data is loaded...');
    $scope.print.sections = angular.copy($scope.sections);
    var promise = getAllSections($scope.print.sections);

    promise.then(function () {
        $scope.dataLoading = false;
        alert('Dataload complete!');
    })

};

function getAllSections(sections) {
    var deferred = $q.defer();
    deferred.notify('Getting Data');
    for (var i = 0; i < $scope.print.sections.length; i++) {
        getSectionData($scope.print.sections[i]);
    }
    deferred.resolve('Data Complete')
    return deferred.promise;
};

我的问题是函数“getSectionData”调用下面我的服务中的多个函数(为了简洁起见，这只是服务的一部分):

angular.module('myModule').service('contractorService', [
     '$http', '$q', function ($http, $q) {

         this.getcompletioncertificatepage = function () {
             return $http.post('/SSQV4/SSQV5/Contractor/GetCompletionCertificate')
         };
         this.getselectedcontractorservices = function (id) {
             return $http.post('/SSQV4/SSQV5/Contractor/GetSelectedContractorServices?sectionId=' + id)
         }
         this.getavailablecontractorservices = function (id) {
             return $http.post('/SSQV4/SSQV5/Contractor/GetAvailableContractorServices?sectionId=' + id)
         };

         this.getgeneraluploadimage = function (id) {
             return $http.post('/SSQV4/SSQV5/Contractor/GetGeneralUploadDocument?imageType=' + id)
         };
         this.getemrtabulation = function () {
             return $http.post('/SSQV4/SSQV5/Contractor/GetEMRTabulationColumns')
         };

         this.getimage = function (id, docDate) {
             return $http.post('/SSQV4/SSQV5/Contractor/GetImage', {"emrDetailID": id, "docDate" : docDate})
          };
         this.getemrquestion = function () {
             return $http.post('/SSQV4/SSQV5/Contractor/GetEMRQuestion')
         };

在我的 Controller 中，我这样调用它们:

       function getSectionData(section) {
            var id = section.QuestionSectionID;
                    contractorService.getIncidentColumns(clusterId)
                    .success(function (data) {
    ...}
                contractorService.getgeneralincidentquestions(id)
                .success(function (data) {
...}

    ... (there are many calls to the service here)
        }

我正在尝试弄清楚如何将 promise 与服务一起用于我必须调用和链接它们的每个函数，以便我的“selectAll”函数中的“then”函数不会显示，直到所有get函数已经完成。我尝试将其放入服务中:

       this.getIncidentDetailByQtr = function (id) {
     var deferred = $q.defer();
     $http.post('/SSQV4/SSQV5/Contractor/GetIncidentDetailByQtr?tabId=' + id)
     return deferred.promise;
 };

在 Controller 中:

            var promise = contractorService.getIncidentDetailByQtr(7)
            .then(function (data) {
                $scope.qtrDetail = data;
                deleteTableRows($scope.qtrDetail);
            });

这有效，直到我尝试向其他调用添加更多 promise (即 var PromiseA 等)。

当我尝试这样做时:

                var promise = contractorService.getIncidentDetailByQtr(7)
                .then(function (data) {
                    $scope.qtrDetail = data;
                    deleteTableRows($scope.qtrDetail);
                });
                $scope.incidentTableDefinition = '<table>' + firstRow + secondRow + thirdRow + '<tr style="text-align:center" ng-repeat="q in qtrDetail">' + repeatRow + '</tr></table>';
                firstRow = '';
                secondRow = '';
                thirdRow = '';
                repeatRow = '';
                var promiseA = contractorService.getincidentsummarycolumns(9)
                .then(function (data) {
                    $scope.summaryColumns = data;

我收到错误“无法获取未定义或空引用的属性“then””。

函数“getSelectedData”对服务进行了大约 15 次调用。我需要最初的“解决”，直到所有这些都完成后才执行。我对此很陌生，但我很确定这与链接 promise 有关，但我不知道如何完成我在这里需要的东西。非常感谢任何帮助!

Answer 1

对“$q.all”进行一些研究后，得到以下结果:

 $scope.selectAll = function () {
        alert('Please wait while your data is loaded...');
        $scope.print.sections = angular.copy($scope.sections);
        var promise = getAllSections($scope.print.sections);

        promise.then(function () {
            $scope.dataLoading = false;
            alert('Dataload complete!');
        })

    };
    function getAllSections(sections) {
        var promises = [];
        angular.forEach(sections, function (section) {
            var promise = getSectionData(section)
            promises.push(promise);
        });
        return $q.all(promises);
    }

希望这对其他人有帮助。快乐编码!