我正在尝试加载脚本https://apis.google.com/js/api.js?onload=initGapi
从 Angular 2 服务中调用 Google API,但是每当我尝试在脚本加载和初始化完成后返回一个值时,async
Pipe 不想将值呈现给模板。
我正在使用一个EventEmitter
当gapi.load()
and gapi.client.init
已完成,并且可观察对象在组件中订阅它。异步管道似乎不想读取该值,直到我单击同一组件中的按钮(可能还触发更改检测)。当我使用时,强制组件内的更改检测不起作用tick()
from ApplicationRef
.
加载 Google API 的服务如下:
google-api.service.ts
import { Injectable, EventEmitter } from '@angular/core';
import { Observable } from 'rxjs/Observable';
import { User, Client } from '../../+home/models';
declare var gapi: any;
@Injectable()
export class GoogleApiService {
CLIENT_ID: string = '....apps.googleusercontent.com';
DISCOVERY_DOCS: string[] = ["https://www.googleapis.com/discovery/v1/apis/admin/directory_v1/rest"];
SCOPES = 'https://www.googleapis.com/auth/admin.directory.user.readonly';
authEmitter: EventEmitter<boolean> = new EventEmitter();
constructor() {
window['initGapi'] = (ev) => {
this.handleClientLoad();
};
this.loadScript();
}
loadScript() {
let script = document.createElement('script');
script.src = 'https://apis.google.com/js/api.js?onload=initGapi';
script.type = 'text/javascript';
document.getElementsByTagName('head')[0].appendChild(script);
}
handleClientLoad() {
gapi.load('client:auth2', this.initClient.bind(this));
}
initClient() {
gapi.client.init({
discoveryDocs: this.DISCOVERY_DOCS,
clientId: this.CLIENT_ID,
scope: this.SCOPES
}).then(() => {
this.authEmitter.emit(true);
});
}
get gapi(): Observable<any> {
return this.authEmitter.map(() => 'hello world');
}
}
以及从服务中读取的组件
应用程序组件.ts
import { Component, OnInit } from '@angular/core';
import { Observable } from 'rxjs/Observable';
import { GoogleApiService } from '../../+core/services';
@Component({
template: `
What does the service say?
{{ api$ | async }}
<button (click)="click()">Button</button>`
})
export class InviteEmployeesContainer implements OnInit {
api$: Observable<string>;
constructor(private gApiService: GoogleApiService) {}
ngOnInit() {
this.api$ = this.gApiService.gapi;
this.gApiService.gapi.subscribe((result) => {
console.log(result);
});
}
click() {
console.log('clicked');
}
}
结果页面打印出字符串What does the service say?
并且有一个按钮,但不打印文本hello world
直到我单击该按钮(这不是所需的行为),它应该立即在页面上可见。
此外,当我使用订阅并登录控制台时this.gApiService.gapi.subscribe
,它记录hello world
当我期望的时候。
有谁知道我如何使用异步管道来获取hello world
打印到页面时authEmitter
触发一个事件。