Unable to receive all data when concat two observables in rxjs - rxjs

Question

I created two observables from a database:
const roomData$ = estab
.query()
.where('estab.type', 'like', 'rooms')
.then((rooms) => {
rooms.forEach((room) => {
observer.next(room.data);
});
});
}).map(data => ({
roomsData: [
...data.rooms,
],
}));
const hotelData$ = Observable.create((observer) => {
estab
.query()
.where('estab.type', 'like', 'hotels')
.then((hotels) => {
hotels.forEach((hotel) => {
observer.next(hotel.data);
});
});
}).map(data => ({
hotelsData: [
...data.hotels,
],
}));
const hotelContentData$ = Observable.concat(roomData$, hotelData$);
hotelContentData$.subscribe((data) => {
fs.appendFile('data.json', (err) => {
if (err) throw err;
console.log('file has been appended!);
}
})
In the data.json file I found only the data received from the roomData$ observable. I change the order in Observable.concat(hotelData$, roomData$) and now I get the data of hotel observable. Why only one Observable is executed? How can I execute both of them and get data from hotelData$ and roomData$?

Answer 1

Observable.concat will take emissions from a stream until that stream completes, and then move to the next stream. Since you're creating your own observable sequences, be sure to complete each one.
const roomData$ = Observable.create( observer => {
estab
.query()
.where('estab.type', 'like', 'rooms')
.then((rooms) => {
rooms.forEach((room) => {
observer.next(room.data);
});
observer.complete(); // adding this will complete your stream.
});
}).map(data => ({
roomsData: [
...data.rooms,
],
}));
const hotelData$ = Observable.create((observer) => {
estab
.query()
.where('estab.type', 'like', 'hotels')
.then((hotels) => {
hotels.forEach((hotel) => {
observer.next(hotel.data);
});
observer.complete(); // adding this will complete your stream.
});
}).map(data => ({
hotelsData: [
...data.hotels,
],
}));
const hotelContentData$ = Observable.concat(roomData$, hotelData$);
hotelContentData$.subscribe((data) => {
fs.appendFile('data.json', (err) => {
if (err) throw err;
console.log('file has been appended!);
});
});