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Given such observable
Rx.Observable.of([1,2,3,4,5])
which emits a single item (that is an array), what is the operator that will transform this observable to a one that emits 5 single items (or whatever the array consists of)?
The example is on .of, but it would be the same for fetching arrays via promises, there might be many other examples. Don't suggest to replace of with from
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concatMap operator is basically a combination of two operators - concat and map. The map part lets you map a value from a source observable to an observable stream. Those streams are often referred to as inner streams.
Flattening operators come to our rescue when we have a nested subscription i.e subscribing to an observable within another subscription. This can be pretty annoying to track and debug. Its similar to “Callback hell” scenario where we have nested callbacks.
RxJS' of() is a creational operator that allows you to create an RxJS Observable from a sequence of values. According to the official docs: of() converts the arguments to an observable sequence. In Angular, you can use the of() operator to implement many use cases.
Pipeable Operators and Creation Operators are the two kinds of operators in RxJS. The Pipeable Operators are methods that take an Observable as input and return another Observable. They can be piped to Observables using the syntax observableInstance. pipe(operator()) .
I can't think of an existing operator to do that, but you can make one up :
arrayEmitting$.concatMap(arrayValues => Rx.Observable.merge(arrayValues.map(Rx.Observable.of)))
or the simpler
arrayEmitting$.concatMap(Rx.Observable.of)
or the shortest
arrayEmitting$.concatMap(x => x)
That is untested so let me know if that worked for you, and that uses Rxjs v4 API (specially the last one). This basically :
concatMap)
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