http get request returns null on first call- Angular 4

[LJ]

Hi, 

Learning and practicing MEAN for couple weeks now and was able to make http get request api. 

My Angular front end has button and onclick it calls method angular component  -> then service ( all in TS). Service calls express backend to return json data.

Calls sequence & results in same order -->

Angular html page ( button + table of results returned by button click) -> Angular component TS -> Angular Service TS ( http get to express backend here) -> Express Router (Promise End http request to external server)

Angular http request is very simple and not using any fancy apis :

http.get(url).subscribe();

Express usings promise/then and http.request(options, function(res){})

Now, console.log at each level, I noticed that on first button click, my json at component level ( returned by service later)  is null and thus first button click, results are not displayed on page. Second click, it works. 

Why is that so? and do I need to introduce Observables here in Angular Service ?

[Sander Elias]

Hi Lj,

Probably there is something off in the way you have wired up processing the results of the get. Normally you never use subscribe in a service.

Regards

Sander

[LJ]

Did you mean .subscribe() - is not required for Angular 4.

this.http.get(URL).subscribe(data=>{this.results.data})

this.results = this.http.get(URL)

Are these 2 same? I think i get error that way.

In my issue, above, request is sent on first click and returned back, only that it is not sent back to front page. I can see it logged in service but not back in component. I thought bug is on the front end code somewhere.