Question

我第一次使用switchMap。它告诉我要返回“某物”，但是当我返回时不起作用。

 @Effect()
  subData$ = this.actions$.pipe(
    ofType(ActionTypes.SEARCH_SUB_DATA),
    map(action => action['payload']),
    switchMap(payload => { //Payload gets highlighted in red
      const repos = this.githubSearch.getRepos(payload);
      const followers = this.githubSearch.getFollowers(payload);
      const starred = this.githubSearch.getStarred(payload);
      return forkJoin([repos, followers, starred]).subscribe(results => {
        this.store.dispatch(
          new UserActions.SuccessSubData({
            user: payload,
            repos: results[0],
            followers: results[1],
            starred: results[2]
          })
        );
        return of(results);
      });
    })
  );

'（payload：never）=>订阅类型的参数不可分配到类型'（值：从不，索引：数字）=>的参数 ObservableInput <{}>'。不能将“订阅”类型分配给该类型 'ObservableInput <{}>'。

基于提供的答案进行更新

@Effect()
      subData$ = this.actions$.pipe(
        ofType(ActionTypes.SEARCH_SUB_DATA),
        map(action => action['payload']),
        switchMap(payload => {
          return forkJoin(
            this.githubSearch.getRepos(payload),
            this.githubSearch.getFollowers(payload)
          );
        }).subscribe(results => {
          this.store.dispatch(
            new UserActions.SuccessSubData({
              user: payload,
              repos: results[0],
              followers: results[1]
            })
          );
        })
      );

这是显示错误的图片

image from error

Answer 1

@Effect()
  subData$ = this.actions$.pipe(
    ofType(ActionTypes.SEARCH_SUB_DATA),
    map(action => action['payload']),
    switchMap(payload => {
      return forkJoin(
        this.githubSearch.getRepos(payload),
        this.githubSearch.getFollowers(payload)
      ).pipe(map(([repos,followers]) => //return success action here), catchError(error => of(//return failaction))
    })
  )

通常，您无需订阅，它只会返回流并让ngrx处理subscriptiona和unsubscription。所以在这里我映射成功和失败的回调动作。它们将由ngrx自动触发。

Answer 2

您正在尝试将Observable与Subscription合并，并且在使用forkJoin时还要使用两个undefined值。以下代码必须适合您的情况。

@Effect()
  subData$ = this.actions$.pipe(
    ofType(ActionTypes.SEARCH_SUB_DATA),
    map(action => action['payload']),
    switchMap(payload => {
      return forkJoin(
        this.githubSearch.getRepos(payload),
        this.githubSearch.getFollowers(payload)
      );
    })
  ).subscribe(results => {
      this.store.dispatch(
        new UserActions.SuccessSubData({
          user: payload,
          repos: results[0],
          followers: results[1]
        })
      );
    });

在Rxjs中返回SwitchMap-Angular

2 个答案: