我必须在这里做错事,但我不知道是什么......我是一个Angular2新手在我的第一个ng2应用程序中磕磕绊绊.
我正在尝试从组件内访问服务上的方法,但该服务仅在构造函数()和ngOnInit()中定义,它在我的其他组件函数中返回为未定义.
这与此问题类似,但我使用的是private关键字,但仍然存在问题.
这是我的服务:
import { Injectable } from "@angular/core";
import { AngularFire,FirebaseListObservable } from 'angularfire2';
import { User } from './user.model';
@Injectable()
export class UserService {
userList$: FirebaseListObservable;
apples: String = 'Oranges';
constructor(private af: AngularFire) {
this.initialize();
}
private initialize():void {
this.userList$ = this.af.database.list('/users');
}
getTest(input:String):String {
return "Test " + input;
}
getUser(userId:String):any {
//console.log('get user',userId);
let path = '/users/'+userId;
return this.af.database.object(path);
}
}
我的组件:
import { Component, OnInit } from '@angular/core';
import { ActivatedRoute } from '@angular/router';
import { UserService } from '../../shared/user.service';
@Component({
moduleId: module.id,
selector: 'user-detail',
templateUrl: 'user-detail.component.html'
})
export class UserDetailComponent implements OnInit {
routeParams$: any;
one: String;
two: String;
three: String;
constructor(private usrSvc:UserService,private route:ActivatedRoute) {
console.log('constructor',usrSvc); // defined here
this.one = usrSvc.getTest('this is one'); // works correctly
}
ngOnInit() {
console.log('ngOnInit',this.usrSvc); // also defined here
this.two = this.usrSvc.getTest('this is two'); // also works correctly
this.routeParams$ = this.route.params.subscribe(this.loadUser);
}
loadUser(params:any) {
console.log('loadUser',this.usrSvc); // undefined!!
this.three = this.usrSvc.getTest('this is three'); // BOOM
}
ngOnDestroy() {
if (this.routeParams$) {
console.log('unsub routeParams$');
this.routeParams$.unsubscribe();
}
}
}
Günter Zöchb.. 5
这是你传递函数的方式
this.routeParams$ = this.route.params.subscribe(this.loadUser);
应该
this.routeParams$ = this.route.params.subscribe(this.loadUser.bind(this));
要么
this.routeParams$ = this.route.params.subscribe((u) => this.loadUser(u));
否则this不会指向您当前的类,而是指向可观察的某个地方(从其所谓的位置)
这是你传递函数的方式
this.routeParams$ = this.route.params.subscribe(this.loadUser);
应该
this.routeParams$ = this.route.params.subscribe(this.loadUser.bind(this));
要么
this.routeParams$ = this.route.params.subscribe((u) => this.loadUser(u));
否则this不会指向您当前的类,而是指向可观察的某个地方(从其所谓的位置)
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