Question

我试图创建一个Ionic 4应用程序，并使用SQLite作为存储。我已经安装了以下软件包：

ionic cordova plugin add cordova-sqlite-storage
npm install --save @ionic-native/sqlite
ionic cordova plugin add uk.co.workingedge.cordova.plugin.sqliteporter
npm install --save @ionic-native/sqlite-porter

这是我的app.module：

@NgModule({
  declarations: [AppComponent],
  entryComponents: [],
  imports: [BrowserModule, IonicModule.forRoot(), AppRoutingModule, 
HttpClientModule],
  providers: [
    StatusBar,
    SplashScreen,
    { provide: RouteReuseStrategy, useClass: IonicRouteStrategy,  },
    SQLite,
    SQLitePorter,
    DatabaseService
  ],
  bootstrap: [AppComponent]
})

这是我的DatabaseService的代码抛出错误的部分，它在.create上失败并返回undefined：

initializeDatabase(): void {
    console.log("initializing db");
    // Define the application SQLite database
    this._SQL
      .create({
        name: this._DB_NAME,
        location: "default"
      })
      .then((db: SQLiteObject) => {
        // Associate the database handler object with the _DB private property
        this._DB = db;
        console.log("db created");
      })
      .catch(e => {
        console.log(e);
      });
}

这是我的错误： TypeError: Cannot read property 'then' of undefined at DatabaseService.push../src/app/services/database.service.ts.DatabaseService.initializeDatabase (database.service.ts:49) at new DatabaseService (database.service.ts:33) at _createClass (core.js:21263) at _createProviderInstance (core.js:21225) at resolveNgModuleDep (core.js:21189) at NgModuleRef_.push../node_modules/@angular/core/fesm5/core.js.NgModuleRef_.get (core.js:21897) at resolveDep (core.js:22268) at createClass (core.js:22148) at createDirectiveInstance (core.js:22019) at createViewNodes (core.js:23245)

请帮助，我已经坚持了两天。

Answer 1

如果在浏览器中对其进行测试，则会引发错误，因为Cordova仅在移动设备上运行。您必须在移动设备或仿真器中测试应用程序

Cordova将仅在Android和Ios等移动平台上运行

Ionic 4 SQLite“无法读取未定义的属性'then'”错误

1 个答案: