如何切换映射3个可观察对象的流

由二湿胸发布于 2020-04-09 06:05:20

我必须将3个Observable流合并为一个。我正在使用Angular和Firebase，这是应该如何工作的...

Step 1: I send a query to Firebase and receive an array. I will use the id from a specific property to query something else for the Step 2.

Step 2: I use the ID from Step 1 to get data from another collection, for this I'll receive another array. In this array, I have another ID that I need for Step 3.

步骤3：我需要使用步骤2上提供的ID从数据库中获取对象。

In order to get this working, I'm using switchMap() but the problem is that I'm getting VOID as result of the method.

请帮助！

getPanic() {
    this.panicService.getPanic(this.checkID)
        .pipe(
            switchMap(panicData => {
                const panic = panicData.map(snaps => {
                    const panicObj: Panic = {...snaps.payload.doc.data()};
                    return this.panicService.getActions(panicObj.id).pipe(map(actionSnaps => {
                        const actions = actionSnaps.map(actionSnap => {
                            const actionsObj: PanicActions = {...actionSnap};
                            const user = this.userService.getUser(actionsObj.executor).pipe(map(userSNAP => {
                                return {...panicObj, ...actionsObj, ...userSNAP};
                            }));
                        });
                    }));
                });
                return forkJoin(panic);
            })
        )
        .subscribe(data => {
            // The panicInfo is of type 'Panic' but I get a TS Lint error that says:
            // Type 'void[]' is missing the following properties from type 'Panic': id, checkId, city, geolocation, and 10 more
            this.panicInfo = data;
        });
}

沫沫浅言

2020-04-09 06:05:20

最好将流分开，这样您就可以看到问题出在哪里。

getActionUsers(actionSnaps) {
  const actions = actionSnaps.map(actionSnap => {
    const actionsObj: PanicActions = {...actionSnap};
    // need to return inside map
    return this.userService.getUser(actionsObj.executor).pipe( 
      map(userSNAP => ({...actionsObj, ...userSNAP})) // combine only action and user here
    );
  });
  // need to combine and return (deal with empty)
  return actions.length ? combineLatest(...actions) : of([]);
}

getPanicActions(panicData) {
  const panic = panicData.map(snaps => {
    const panicObj: Panic = {...snaps.payload.doc.data()};
    return this.panicService.getActions(panicObj.id).pipe(
      switchMap(actionSnaps => this.getActionUsers(actionSnaps).pipe(
        map(res => ({...panicObj, ...res})) // add panicObj here
      ))
    );
  });
  // forkJoin only works on observables that complete, use combineLatest when they don't, also need to deal with empty
  return panic.length ? combineLatest(...panic) : of([]);
}


getPanic() {
  this.panicService.getPanic(this.checkID).pipe( 
    switchMap(panicData => this.getPanicActions(panicData))
  ).subscribe(data => {
    // The panicInfo is of type 'Panic' but I get a TS Lint error that says:
    // Type 'void[]' is missing the following properties from type 'Panic': id, checkId, city, geolocation, and 10 more
    this.panicInfo = data;
  });
}

梅Oo

2020-04-09 06:05:20

测试此代码：

getPanic() {
  this.panicService.getPanic(this.checkID)
    .pipe(
      switchMap((panicData: any[]) => forkJoin(
        ...panicData.map(snaps => {
          const panicObj = { ...snaps.payload.doc.data() };

          return this.panicService.getActions(panicObj.id).pipe(
            switchMap((actionSnaps: any[]) => forkJoin(
              ...actionSnaps.map(actionSnap => {
                const actionsObj: any = { ...actionSnap };

                return this.userService.getUser(actionsObj.executor).pipe(
                  map(userSNAP => ({ ...panicObj, ...actionsObj, ...userSNAP })),
                );
              }),
            )),
          );
        }),
      )),
    )
    .subscribe(data => {
      // The panicInfo is of type 'Panic' but I get a TS Lint error that says:
      // Type 'void[]' is missing the following properties from type 'Panic': id, checkId, city, geolocation, and 10 more
      this.panicInfo = data;
    });

my example on stackblitz

我不知道您在请求中收到什么数据。

二湿胸

这家伙很懒，什么都没留下

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