Convert static object to Observable and forkjoin

Question

I have an object and need to combine it with an observable.

The object looks like this:

obj1

let org1Obj = {"category": "1", "testkey": "testvalue"}

The results with JSON.stringify of the observable looks like this:

obj2

[{"id":"51XXgI1w77VerovThbUV","question":"Sdad"},
 {"id":"FxjDsyLBGqtrBx1EHFyM","question":"exanoke"}]

I then have an observable that fetches data and I'm thinking of using forkJoin to combine the two so I end up with the following result:

{"category": "1", 
 "testkey": "testvalue", 
 "questions": [
   {"name": "test1"},
   {"name": "test"}
 ]
}

How do I make org1Obj into an observable so I can use forkJoin on it and how can I add the second observable to "questions": [result from observable]?

Converting a value to an observable that emits a single value? It looks like a misuse of observables. This could be done with simple map. The way how exactly they should be combined remains unclear since the values of the result differ from original objects. — Estus Flask
The reason I need to convert it is so that I can use forkJoin and the reason for forkJoin is because I need to wait until all the data is available from the second observable. If I try to just combine them the data won't be available from the second observable before the function is run. — amunds
Since static object is already available, resulting data will be available in observable map. — Estus Flask

Estus Flask Estus Flask · Accepted Answer · 2017-11-14T19:51:47

This is possible with:

const observable1 = Observable.of(obj1);
return Observable.forkJoin(observable1, observable2).map(([obj1, obj2]) => {
  return Object.assign({}, obj1, { questions: obj2 }); // or so
});

And less complicated and more performant way to do this is to skip forkJoin and map an observable to resulting object:

return observable2.map(obj2 => {
  return Object.assign({}, obj1, { questions: obj2 }); // or so
});

Convert static object to Observable and forkjoin

1 Answers