RXJS可观察到的未在flatMap上完成（Observable :: from）

Question

What I'm trying to do is pull some data from mongodb using streams, do some operations on data, use keys of incoming data to do another query in mongo and then join the data.

The actual code is much more complex but i will illustrate with simpler example.

The problem I have is that on complete never gets fired and I'm assuming because the outer observable never completes.

const o$ = RxNode.fromStream(getDataFromMongo(), 'end'))
    .filter(doSomeFiltering)
    .bufferCount(100)
    .flatMap(bufferedData => {
        let ids = _.map(bufferedData, 'id');

        return RxNode.fromStream(getMoreDataFromMongodb(ids))
            .reduce(createMapIdObject(), {})
            .flatMap(createdMap => {  //because i get here, outer never complets
                return Observable.from(bufferedData)
                .map(item => ({
                    id: item.id,
                    size: createdMap[item.id].size
                }));
            });
    })
    .subscribe(
        c => console.log(c),
        err => console.log(err),
        () => console.log('COMPLETE') // never happens
    );

How can i get the complete to fire? Or is there a better way to do what I'm trying to achieve?

If I chain .finally(() => console.log(done) on Observable.from inside nested flatMap , that gets fired. So inner observable is completing but outer doesn't.

Answer 1

您可以在订阅前简单地添加take(1) 。