如何从热可观察对象返回数据

Question

import { Injectable } from '@angular/core';
import { SearchService } from 'src/app/services/search/search.service';
@Injectable()
export class ManageFlightBookHoldService {
constructor(
private flight_search: SearchService,
) { }
getBookHoldflightData (id:number) {
let flight = this.flight_search.getFlightAdmin(id).subscribe(
function(response){ return (response)}
)
console.log(flight, "fghjk")

}

Answer 1

在一个变量中设置响应，如下所示:

import { Injectable } from '@angular/core';
import { SearchService } from 'src/app/services/search/search.service';
@Injectable() export class ManageFlightBookHoldService {
responseData:any;
constructor( private flight_search: SearchService) { }
getBookHoldflightData (id:number) {
this.flight_search.getFlightAdmin(id).subscribe((response)=>
{ 
this.responseData=response; //store the data in a variable
console.log(this.responseData, "fghjk")
}
)
}

在你的服务中返回一个可观察对象要好得多，这样你的实现选项就很少了:

1. 订阅从service方法返回的可观察对象。然后您可以使用订阅的响应作用域或在变量或行为中设置它:

其中之一是使用BehaviorSubject

BehaviorSubject就像一个具有get和set能力的属性，加上一个额外的功能;你可以订阅它。所以当属性发生变化时，我们就会收到通知，然后我们就可以对

进行操作了

TS:

constructor(private http: HttpClient) {
this.serverMessageSubject= new BehaviorSubject<any>(null);
}
serverMessageSubject: BehaviorSubject<any>;
serverMessage$:Observable<any>;

ngOnInit(): void {
this.getData();
this.serverMessage$= this.serverMessageSubject.asObservable();
this.serverMessage$.subscribe((result)=>
{
console.log("here you can set your files etc...",result)
})
}
getData() {
this.http
.get<any>('http://localhost:8080/get-json')
.pipe(
tap((result) => {
this.serverMessageSubject.next(result);
})
)
.subscribe((data) => {
});
}

HTML:

<div>{{ serverMessage$ | async | json }}</div>

2. 设置从service方法返回的可观察对象，然后你可以在html中使用async pipe来显示响应。