我是Angular2的新手,我有以下服务文件,这给我一个错误。
import { Injectable } from '@angular/core';
import { Http, Response } from '@angular/http';
import { Observable} from 'rxjs/Observable';
import 'rxjs/add/operator/map';
import 'rxjs/add/operator/catch';
import 'rxjs/add/observable/throw';
import 'rxjs/add/observable/from';
import 'rxjs/add/observable/interval';
import 'rxjs/add/operator/take';
@Injectable()
export class UserService {
constructor(private _http: Http) { }
private getUserUrl = 'data/data.json';
private users = [
{ personal: { name: 'Saurabh', age: 24 }, role: 'Web Developer', hobby: 'Coding' },
{ personal: { name: 'Sunil', age: 24 }, role: 'Manual Tester', hobby: 'Drinking tea' },
{ personal: { name: 'Digvijay', age: 24 }, role: 'Onsite Tester', hobby: 'Gaming' },
{ personal: { name: 'Vinod', age: 24 }, role: 'C# Developer', hobby: 'Flirting' }
];
getUsers() {
return Observable.from(this.users) //tried with and without this `.from
.interval(2000)
.take(this.users.length) // end the observable after it pulses N times
.map(function (i) { return this.users[i]; });
}
addUser(user: any) {
this.users.push(user);
}
_errorHandler(error: Response) {
return Observable.throw(error || "Server error");
}
}
我的期望是上面的代码应该一次发出一个用户。我可以在我的组件中订阅该用户并产生延迟的用户加载效果。我的组件代码是:
export class UserComponent implements OnInit {
users :any = [];
constructor(private _userService: UserService, private _router : Router) { }
ngOnInit() {
//this.users = this._userService.getUsers();
//code for real http data : Observable do not send data unless you subscribe to them
this._userService.getUsers().subscribe(response => this.users.push(response));
}
}
我最终使用*ngFor
在DOM上迭代此列表。
但令我惊讶的是,Observable无法找到数组本身并在.map
上出错:
TypeError: Cannot read property '0' of undefined
at MapSubscriber.eval [as project] (http://localhost:8080/app/services/user.service.js:41:50)
如果我只是从我的服务返回用户数组,它工作正常。我在这里有什么好看的吗?
答案 0 :(得分:0)
使用箭头功能。
找不到this.users
,this
在常规函数中已更改。
.map((i) =>this.users[i]);
或者
.map((i)=> { return this.users[i]; });