javascript - Angular 2 : Error during evaluation of click

Question

我通过使用 express 创建的从客户端到服务器的按钮发出请求，在请求处理程序中只有 console.log('Delete from server');每次我点击它都会收到这些错误

angular2.dev.js:23514 ORIGINAL EXCEPTION: T
ypeError: Cannot read property    'request' of undefined
angular2-polyfills.js:143 Uncaught EXCEPTION:
Error during evaluation of   "click"
ORIGINAL EXCEPTION: TypeError: Cannot read property 'request' of undefined
ORIGINAL STACKTRACE:

文件结构是，有两个文件夹server和client，分别有angular和server文件

这里是点击按钮的函数:

 deletefromserver(){
     this.http.request("http://localhost:3000/deletedata").subscribe((res :     Response) => {
        console.log(res.json());
    })     
 }

这是服务器文件中的请求处理程序:

server.get('/deletedata', function(){
console.log('Delete from server');
})

Answer 1

你可能忘了在你的组件中注入(inject) http 服务

你应该有这样的东西:

@Component({...})
class MyComponent {

  constructor(private http: Http) { }

  deleteFromServer() {
    this.http.request("http://localhost:3000/deletedata").subscribe((res : Response) => { console.log(res.json()); })
  }

}

并且不要忘记在您的 Bootstrap 中添加 HTTP_PROVIDERS:

bootstrap(MyComponent, [HTTP_PROVIDERS]);

你的服务器也应该返回一些东西:

server.get('/deletedata', function(req, res) {
  res.json({hello: 'hello world'});
});