TypeScript AngularJS本地存储服务访问IndexedDB，数据库实例是否未定义？

Question

我正在使用TypeScript AngularJS本地存储服务来访问IndexedDB。 实现open（）函数以打开与IndexedDB的连接，并将数据库实例分配给IDBDatabase类型的变量 database （this.database）

当我指定：

  

this.database =（event.target as IDBOpenDBRequest）.result

我确认 this.database 包含数据库的实例。 但问题是 - 当我从控制器调用getForms（）时， this.database 未定义：（

请告知为什么会发生这种情况以及如何解决这个问题。谢谢。

以下是我服务的代码：

namespace App {
    "use strict";

    export class LocalStorage {
        indexedDB: IDBFactory;
        dbName: string;
        tableName: string;
        lastIndex: number;
        database: IDBDatabase;

        static $inject: string[] = ["$window", "$q"];

        constructor(private $window: ng.IWindowService, private $q: ng.IQService) {
            this.indexedDB = $window.indexedDB;
            this.lastIndex = 0;
            this.dbName = "entities";
            this.tableName = "keyvaluepairs";
        }

        open() {
            var deferred = this.$q.defer();
            var request = this.indexedDB.open(this.dbName);
            request.onsuccess = function (event: Event) {
                this.database = (event.target as IDBOpenDBRequest).result;
                deferred.resolve();
            };

            request.onerror = function (event: Event) {
                deferred.reject();
            };

            return deferred.promise;
        };


        getForms() {
            var deferred = this.$q.defer();

            // Problem here: this.database for some reason is undefined,
            // although I have instantiated it in the open() function

            if (this.database) { 

                // my code comes here...
            }

            return deferred.promise;
        };

    }

    app.service("LocalStorage", LocalStorage);

}

以下是我的控制器的代码：

namespace App {
    "use strict";

    /**
     * DetailController
     */
    class DetailController {
        id: number = 15424420;
        form: any;
        message: string;

        static $inject: string[] = ["LocalStorage", "$filter"];

        constructor(private localStorage: LocalStorage, private $filter: ng.IFilterService) {
            this.localStorage.open().then(
                response => this.getForms(), 
                response => this.error(response));
        }

        getForms() {
            this.localStorage.getForms().then(
                response => this.success(response),
                response => this.error(response));
        }

        // Apply filter to find the form we need by ID
        success(data) {
            this.form = this.$filter("filter")(data, { Id: this.id })[0];
            this.message = this.form.Name;

        }

        error(response) {
            this.form = null;
            this.message = response.error.statusText;
        }
    }

    app.controller("DetailController", DetailController);
}