Javascript &引用；无法设置未定义的属性"；AngularJS中的错误

我是个新手，所以我认为我犯了一些愚蠢的错误，但仍然没有抓住它。 我创建了一个服务来获取一些数据，然后将该服务注入到我的控制器中

服务-

  .service('getAllCompanies', ['$http', function ($http) {
    // AngularJS will instantiate a singleton by calling "new" on this function
    var url = "http://localhost:8000/companies/?page=";
    this.getCompanies = function(p) {
        return $http.get(url+p);
    };
  }]);

控制器-

.controller('CompaniesallCtrl', ['getAllCompanies', function (companiesService) {
    var pageNumber = 1;
    this.companiesNumber = "";
    companiesService.getCompanies(pageNumber)
        .then(function(response){
            console.log(response.data.count);
            this.companiesNumber = response.data.count;
        }, function(error) {
            console.log(error);
        })
  }]);

我在控制台中得到这个错误-

TypeError: Cannot set property 'companiesNumber' of undefined
    at companiesall.js:17
    at processQueue (angular.js:16170)
    at angular.js:16186
    at Scope.$eval (angular.js:17444)
    at Scope.$digest (angular.js:17257)
    at Scope.$apply (angular.js:17552)
    at done (angular.js:11697)
    at completeRequest (angular.js:11903)
    at XMLHttpRequest.requestLoaded (angular.js:11836)

log（response.data.count）给出了正确的结果，所以我不明白为什么它显示为未定义。请帮忙

我猜你在用什么？然后

回调中的上下文将是全局对象，但
这个
实际上是
未定义的
。用于保留词法作用域（本例中为控制器实例）：

或更正上下文：

companiesService.getCompanies(pageNumber)
    .then(function(response) {
        console.log(response.data.count);
        this.companiesNumber = response.data.count;
    }.bind(this), function(error) {
        console.log(error);
    })

您还可以将控制器设置为函数范围内的变量

比如：

.controller('CompaniesallCtrl', ['getAllCompanies', function (companiesService) {
    var pageNumber = 1;
    var ctrl = this;
    ctrl.companiesNumber = "";
    companiesService.getCompanies(pageNumber)
        .then(function(response){
            console.log(response.data.count);
            ctrl.companiesNumber = response.data.count;
        }, function(error) {
           console.log(error);
        }) 
}]);

var self=这个；self.compainesNumber=“”；然后（函数（响应）{self.companiesNumber=response.data.count；}）；
.controller('CompaniesallCtrl', ['getAllCompanies', function (companiesService) {
    var pageNumber = 1;
    var ctrl = this;
    ctrl.companiesNumber = "";
    companiesService.getCompanies(pageNumber)
        .then(function(response){
            console.log(response.data.count);
            ctrl.companiesNumber = response.data.count;
        }, function(error) {
           console.log(error);
        }) 
}]);