CODEWITHSUNDEEP
arraysreactive-programmingrxjs
Matt Rea
Matt Rea

Reputation: 157

RxJS: Splitting an array result from Observable.fromPromise

I'm using RxJS here and I can't seem to get over this seemingly simple issue.

rx.Observable
    .from([1,2,3,54,3,22,323,23,11,2])
    .distinct()
    .subscribe(function next (x) {
        console.log('Next');
        console.log(x);
    }, function error (x) {
        console.log('Error');
        console.log(x);
    }, function completed () {
        console.log('Completed');
    });

The above code spits out each array item in order as expected.

rx.Observable
    .fromPromise(getNumbers([1,2,3,54,3,22,323,23,11,2]))
    .distinct()
    .subscribe(function next (x) {
        console.log('Next');
        console.log(x);
    }, function error (x) {
        console.log('Error');
        console.log(x);
    }, function completed () {
        console.log('Completed');
    });

function getNumbers (nums) {
    return new Promise(function (resolve, reject) {
        resolve(nums);
    });
}

Here though I only get the full array (i.e. [ 1, 2, 3, 54, 3, 22, 323, 23, 11, 2 ]). Shouldn't RxJS be breaking the result apart? I'd hope it at least had some logic for this.

Thank you

Upvotes: 12

Views: 13086

Answers (1)

paulpdaniels
paulpdaniels

Reputation: 18663

No it will not break them apart implicitly. If you want to split them use flatMap which will flatten the array:

 rx.Observable
    .fromPromise(getNumbers([1,2,3,54,3,22,323,23,11,2]))
    .flatMap(function(x) { return x; })
    .distinct()
    .subscribe(function next (x) {
        console.log('Next');
        console.log(x);
    }, function error (x) {
        console.log('Error');
        console.log(x);
    }, function completed () {
        console.log('Completed');
    });

Upvotes: 24

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