rxjs observable.of(object) 返回 {“_isScalar”: “”, “value”: {}, “scheduler”: “” } 而不是 value

Question

I am fairly new to rxjs.

I tried to create a function that runs a angular 2 http request like that:

syncFromApi$() {

  // create Headers
  ...

  let ob$ = this.http.post(
    CONFIG_APP.apiEndpoint + '/sync/app',
    '',
    { headers: headers }
  )
  .map((response:Response) => {
    return Observable.of({type: "success", payload: response.json()});
  })
  .catch(function (err:Response) {
    return Observable.of({type: "error", payload: err.json()});
  });

  return ob$;
}

In short, when having success, I am returning an Object which indicates, if the request was successful. After that I want to switch map depending on the returned object:

let o$ = syncFromApi$()
  .switchMap((value) => {
    console.log("value", JSON.stringify(value, null, 0));
    if (data.type === 'success') {
      return Observable.of(1);
    } else if (data.type === 'error') {
      return Observable.of(2);
    }
  });

And here comes the problem I face. The console.log(...) outputs a object like this:

value, {"_isScalar": true, "value": THIS_IS_WHAT_I_NEED_AS_VALUE, "scheduler": null}

But I need only the object I returned with the syncFromApi$ function.

Can anyone explain to me, if I am using observable.of() in the wrong manner?

I tried observable.of(1) and it returns 1 as value. If I use a object ( observable.of({ type: "myType", message: "myMessage" }) ), it returns an object wrapping the object I need with the keys "_isScalar", "value" and "scheduler".

Thanks in advance.

Answer 1

Your problem is in your map operator:

let ob$ = this.http.post(
  CONFIG_APP.apiEndpoint + '/sync/app',
  '',
  { headers: headers }
)
.map((response:Response) => {
  return {type: "success", payload: response.json()}; // <----
})

You need to return an object not an observable. The map operator uses the object like it is and doesn't project the returned observable into the observable chain.

If you want to return Observable.of for some reasons, you need to use the flatMap operator instead:

let ob$ = this.http.post(
  CONFIG_APP.apiEndpoint + '/sync/app',
  '',
  { headers: headers }
)
.flatMap((response:Response) => {
  return Observable.of({type: "success", payload: response.json()});
})

That's fine for the catch operator since it expects an observable to be returned into its associated callback.