Question

两个http调用完成后，我使用Observable.forkJoin（）处理响应，但是如果其中一个返回错误，如何捕获该错误？

Observable.forkJoin(
  this.http.post<any[]>(URL, jsonBody1, postJson) .map((res) => res),
  this.http.post<any[]>(URL, jsonBody2, postJson) .map((res) => res)
)
.subscribe(res => this.handleResponse(res))

Answer 1

您可能catch传递给forkJoin的每个可观察对象中的错误：

// Imports that support chaining of operators in older versions of RxJS
import {Observable} from 'rxjs/Observable';
import {forkJoin} from 'rxjs/add/observable/forkJoin;
import {of} from 'rxjs/add/observable/of;
import {map} from 'rxjs/add/operator/map;
import {catch} from 'rxjs/add/operator/catch;

// Code with chaining operators in older versions of RxJS
Observable.forkJoin(
  this.http.post<any[]>(URL, jsonBody1, postJson) .map((res) => res)).catch(e => Observable.of('Oops!')),
  this.http.post<any[]>(URL, jsonBody2, postJson) .map((res) => res)).catch(e => Observable.of('Oops!'))
)
.subscribe(res => this.handleResponse(res))

还要注意，如果使用RxJS6，则需要使用catchError而不是catch，并且需要pipe运算符而不是链接。

// Imports in RxJS6
import {forkJoin, of} from 'rxjs';
import {map, catchError} from 'rxjs/operators';

// Code with pipeable operators in RxJS6
forkJoin(
  this.http.post<any[]>(URL, jsonBody1, postJson) .pipe(map((res) => res), catchError(e => of('Oops!'))),
  this.http.post<any[]>(URL, jsonBody2, postJson) .pipe(map((res) => res), catchError(e => of('Oops!')))
)
  .subscribe(res => this.handleResponse(res))

Answer 2

这对我有用：

forkJoin(
 this.http.post<any[]>(URL, jsonBody1, postJson).pipe(catchError(error => of(error))),
 this.http.post<any[]>(URL, jsonBody2, postJson)
)
.subscribe(res => this.handleResponse(res))

即使第一次调用发生错误，第二次HTTP调用也将正常调用

Answer 3

您在这些行之间尝试过什么吗？

const todo1$ = this.myService.getTodo(1);
const error$ = this.myService.getTodo(201);
const todo2$ = this.myService.getTodo(2);
forkJoin([todo1$, error$, todo2$])
  .subscribe(
    next => console.log(next),
    error => console.log(error)
  );

请记住，如果在某个时间点任何输入可观察到的错误，forkJoin也将错误，并且所有其他可观察到的对象将立即被取消订阅。

如何在Observable.forkJoin（...）中捕获错误？

3 个答案: