Previously, I asked an issue about return nested httprequest with wait subrequest.
https://stackoverflow.com/questions/69308614/angular-map-wait-observable-to-complete[Angular map wait Observable to complete]1
I made some changes to it, but it throw error
Error: You provided 'undefined' where a stream was expected. You can provide an Observable, Promise, Array, or Iterable.
Here are my update code
test2(): Observable<Student[]> {
return this.test1().pipe(
mergeMap((result) => {
if (!result) {
return of(result);
}
return forkJoin(
result.map((rr) => {
if (rr.age === 1) {
rr.age = rr.age * 10;
return of(rr);
} else {
this.client
.get('https://api.coindesk.com/v1/bpi/currentprice.json')
.pipe(
map((res) => {
console.log(res);
rr.age = rr.age * 10000;
return rr;
})
);
}
})
).pipe(
map((paths) => {
console.log('w');
console.log(paths);
return paths;
// return result.map((e, index) => ({
// age: paths[index],
// }));
})
);
})
);
}
The issue in your code is that you are using a condition inside your .map. If you are using a condition in .map function, you need to add return because as the error states that a stream was expected instead of undefined. In order for you to provide an observable, you need to return your observable inside your if-else condition.
In the code below, I added the keyword return on your of() and on your http call. I also created a stackblitz containing my solution for you to check.
test2(): Observable < Student[] > {
return this.test1().pipe(
mergeMap((result) => {
if (!result) {
return of(result);
}
return forkJoin(
result.map((rr) => {
if (rr.age === 1) {
rr.age = rr.age * 10;
return of(rr);
} else {
return this.client
.get('https://api.coindesk.com/v1/bpi/currentprice.json')
.pipe(
map((res) => {
console.log(res);
rr.age = rr.age * 10000;
return rr;
})
);
}
})
).pipe(
map((paths) => {
console.log('w');
console.log(paths);
return paths;
})
);
})
);
}