如何使Angular组件UI等待异步功能

Question

我正在做的是我正在订阅一个http get函数，该函数在我的singup组件中验证我的用户。现在我想要的是我想让它等到我获取数据并导航到我的内部页面。验证成功后，我试图导航到内部页面。但它在UI准备就绪后才起作用。我的意思是我在刷新1秒后仍然看到注册页面。代码如下

  this._restapiService.validate()
          .subscribe(data=>{
              if(data.success){
                this._router.navigate(['contacts']);
              }
          });

我试着把这段代码放在constructor（）和ngInit（）中，但同样的事情正在发生。

Answer 1

正如@yurzui在评论部分中所提到的，如果防护验证失败，则角度防护会阻止视图呈现（如果防护失败，则不会触发组件生命周期）。

查看此示例代码段，您可以使用该代码段为应用程序中的经过身份验证的视图添加防护 -

警卫定义

import { Injectable } from "@angular/core";
import { CanActivate, ActivatedRouteSnapshot, RouterStateSnapshot } from "@angular/router";

@Injectable()
export class LoggedInGuard implements CanActivate {

    constructor() { }

    public canActivate(route: ActivatedRouteSnapshot, state: RouterStateSnapshot): Promise<any> {
        return new Promise<any>((resolve: Function, reject: Function) => {
            //this is where you need to validate the user
            //it can be an AJAX call
            let response: any;
            //assuming the AJAX call is made here
            //response = HttpService.getData();

            //resolve indicates user is validated by the service and guard allows user to land on the reuqested view.
            //reject on the other hand, will stop user from landing on requested view
            //this logic can be customised.
            response.success ? resolve() : reject();
        });
    }
}

---

路线定义

import { Route } from "@angular/router";
import { HomeComponent } from "./components/home.component";
import { LoginComponent } from "./components/login.component";

export const routes: Route[] = [{
        path: "route",
        canActivate: [LoggedInGuard],
        component: HomeComponent,
    },{
        path: "*",
        component: LoginComponent,
    }];

检查这个SO answer知道如何触发多个警卫串联，因为它大多数时候会产生问题，因为角度不会连续发射防护装置。

我希望这可以帮助你。